Indian Patents. 252875:CONTINUOUS SILAZANE CLEAVAGE METHOD

Title of Invention	CONTINUOUS SILAZANE CLEAVAGE METHOD
Abstract	Title: Continuous silazane cleavage method. A silazane cleavage method comprising reacting a silazane compound with a cleaving reagent, wherein at least one of the silazane compound and the cleaving reagent is introduced in gaseous form and wherein said method is carried out continuously.

Full Text	Continuous silazane cleavage method Description The present invention relates to a continuous silazane cleavage method, in particular for the production of molecular precursors for non-oxide inorganic ceramics. Silazane cleavage reactions which are carried out batchwise have already been described in the prior art (Metallo-organicheskaya Khimiya (1989), 2(3), 701-2, Kalikhman, I.D. et al.; Journal of Organometallic Chemistry (1989), 361(2), 147-55, Kalikhman, I.D. et al.; Zhurnal Obshchei Khimii (1981), 51(8), 1824-9, Sheludyakov, V.D. et al.). Ceramics prepared from the anionic components C and N together with 2 to 4 further elements such as B, Al, Ga, In, Si, Ge, P, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Fe or Zn having a cationic function are of particular interest. Such ceramics, for example consisting of Si, B, N and C, are distinguished by excellent thermal, mechanical and chemical resistance and, in terms of their combination of all applicational properties, are distinctly superior to competing materials, for example for use in heat engines. A prerequisite for achieving these advantageous properties is the creation of a network with a regular alternation of elements with an anionic and cationic function, the latter homogeneously distributed over zones of above 1 to 2 nm. Such prerequisites may be achieved by the synthesis and provision of molecular single component precursors, which contain the particular desired combination of cationic components linked to one another via nitrogen. These molecular precursors are then polymerised and finally ceramised by pyrolysis. Since the polymeric intermediate stages may be processed using any polymer processing method, an unusually wide range of forms of use is accessible, such as for example fibres, films, infiltrates, coatings and mouldings. The potential of this new family of materials for the production of fibre-reinforced ceramic composites is of particular significance. Unequalled properties at elevated temperatures in air and with simultaneous mechanical loading are the guarantee of potential applications. Penetration into areas occupied by metallic and conventional ceramic materials is desirable due to the numerous technical advantages, but only possible if an inexpensive production process is available. The review article "Amorphous Multinary Ceramics in the Si-B-N-C System" (M. Jansen et al., Struct. Bond. 2002, 101, 137) and DE41 07 108A1, DE 100 45 427 A1, DE 100 45 428 A1 and 101 04 536 A1 describe syntheses for the Si/B/N/C subsystem for the variants of the molecular scaffold for a single component precursor of the formula (1) RxHal3-xSiNR1-BRyHal2-y wherein R in each case independently represents a hydrocarbon residue with 1 to 20 C atoms, Hal in each case independently means CI, Br or I, R1 in each case independently represents a hydrocarbon residue with 1 to 20 C atoms or hydrogen, x = 0, 1 or 2 and y = 0 or 1. A feature which is common to the above-described methods is that the particular target molecule is synthesised in batch mode starting from Me3Si- NR1SiMe3 by two successive silazane cleavage reactions, firstly with SiHal4-xRx, then with BHal3.yRy. These are laboratory syntheses which cannot straightforwardly be carried out as environmentally and economically optimised production methods on an industrial scale. The following may in particular be problematic: 1. Reaction times for the first silazane cleavage are between 20 and 48 hours, for the second approx. 12 hours per batch. Satisfactory space-time yields thus cannot be achieved via this route. 2. If reaction temperatures are increased, selectivity declines and undesired secondary products such as RxHal3-xSi-NR1-SiHal3-xRx or Me3Si-NR1- SiHal2-xRx-NR1-SiMe3 may be formed. 3. Large excesses of costly feed materials have hitherto been necessary, the costs of which impair the economic viability of the method. 4. Synthesis by the "batch" method is comparatively uneconomic, since each reaction batch is preceded by a time-consuming and costly provision of an inert atmosphere in the reaction apparatus. 5. High costs are generated by the necessary cooling during synthesis and by the isolation and purification of the product by distillation processes. DE100 45 428A1 describes an alternative preparative route to yield the above defined single component precursors, according to which an amine component R1NH2 is reacted in succession with a silane component SiHal4-xRx and a borane component BHal3-yRy: In this sequence of two successive aminolysis reactions, the formation of difficult to separate saline hydrochlorides, which inevitably occurs in both steps, is disadvantageous and additionally considerably diminishes product yield relative to the introduced material. Nonetheless, this approach has made it possible to achieve a continuous production method, in which the reactor is cycled between a production phase and a regeneration phase (stripping of hydrochlorides) (DE 102 28 990 A1). While the described method already yields good results, it still exhibits disadvantages from a technical and economic standpoint: 1. The space-time yield is reduced by the intermittent mode of operation. The only remedy is to install a parallel reactor (so increasing capital investment). 2. Half of the amine starting component and half of the silylamine intermediate stage are bound as hydrochlorides and discharged during the regeneration cycle. This considerably reduces the yield of final product relative to the valuable feed materials. 3. The target products require elaborate isolation and purification. 4. Residues of intermediate and final product are pyrolysed during thermal stripping and accordingly result in reactor fouling over long-term operation. Many compounds of interest and in particular molecular single component precursors for non-oxide ceramics may be produced by silazane cleavage. Hitherto known batch methods, however, exhibit the disadvantages discussed above. It was accordingly an object of the present invention to provide a method for cleaving silazane compounds which at least partially overcomes the disadvantages of the prior art. A further object of the present invention was to provide an efficient, generally applicable method for the production of single component precursors for non-oxide ceramics which should in particular satisfy the following requirements: - it should be possible to carry out the method continuously, without separate isolation or storage of the intermediate stage. - product yield should be optimal, such that the feed materials are converted as completely as possible into the product. The invention relates to a method for cleaving silazane compounds, which is characterised in that it is carried out continuously. It has surprisingly been found that silazane cleavage may be carried out continuously, so making it possible to overcome the above-stated disadvantages with regard to a poor space-time yield. Silazanes are silicon-nitrogen compounds which comprise an Si-N bond. Element-N compounds can be synthesised by silazane cleavage. It has furthermore been found according to the invention that a continuous mode of operation of the method is in particular advantageous and possible if at least one of the educts introduced for silazane cleavage is used in gaseous form. The silazane or the cleaving reagent or both may here be introduced in gaseous form. In a preferred embodiment, all the educts are introduced in gaseous form and the reaction proceeds in the gas phase. In a further preferred embodiment, at least one educt is introduced in gaseous form and at least one other educt is introduced in liquid form. When this approach is used, the method is advantageously performed countercurrently, whereby it is possible to achieve conversion which is virtually quantitative or even quantitative. When the reaction is carried out in this manner, at least one reaction stage advantageously takes the form of a gas-liquid reactor, for example a bubble column, spray column, packed column, falling-film reactor or reactor with external recirculation. A further improvement of the continuous method according to the invention may be achieved by removing the target product and/or undesired secondary products from the reaction mixture and thus from the equilibrium. The target product may be isolated from the remaining components of the reaction mixture for example by crystallisation, condensation and/or using a solvent. Secondary products, in particular highly volatile secondary products, are preferably removed from the reaction mixture by partial condensation, distillation, pervaporation, gas permeation or adsorption. Phase separation between the condensate phase and gas phase preferably proceeds in an inertial separator or in a cyclone. Using the continuous mode of operation of the method according to the invention, it is in particular possible to achieve elevated selectivity with regard to the desired target products. Selectivity may further be ensured by carrying out the reaction with one of the educts in in which x = 0 or 1, y = 0, 1 or 2 and z = 0, 1, 2 or 3, Hal is selected from F, CI, Br and I, and R represents hydrogen or a hydrocarbon residue with 120 C atoms, and a compound of the formula (4) selected from BHal3-xRx, AIHal3-xRx, GaHal3-xRx, lnHal3-xRx, SiHal4-yRy, GeHal4-yRy, PHal3-xRx, PHal5-zRz, TiHal4-yRy, ZrHal4-yRy, VHal3.xRx, VHal4-yRy, NbHal5-zRz, TaHal5-zRz, CrHal3-xRx, MoHal4-yRy, MoHal5-zRz, WHal6-zRz, FeHal3-xRx or ZnCI2 in which x = 0 or 1, y = 0, 1 or 2, z = 0, 1, 2 or 3, Hal is selected from F, CI, Br and I, and R represents hydrogen or a hydrocarbon residue with 1-20 C atoms. In this embodiment, two silazane cleavage reactions are carried out. In these two reactions, the compounds of the formulae (3) and (4) are preferably present in gaseous form. It has surprisingly been found the method for the production of molecular single component precursors for non-oxide ceramics may be carried out continuously. The reaction of the silazane compound with a compound of the formula (2) preferably proceeds in the gas phase. Alternatively, one of the two reactants may be introduced in the form of a liquid. In this case, the compound of the formula (3) is preferably present in the liquid phase and the compound of the formula (2) in the gaseous phase. The product of silazane cleavage is obtained in liquid form, whereby the desired products may be produced inexpensively and on a large scale. The method according to the invention for the production of compounds with the structural feature X-N-Y, in particular of compounds with the formula (1) RxHal3-xSi-NR1BRyHal2-y proceeds via a two-fold silazane cleavage from R23SiNR1SiR33 (3). In formula (3), R2 and R3 may preferably in each case independently mean an alkyl and/or aryl residue with 1-7 C atoms, preferably a methyl residue. The silazane cleavage according to the invention and in particular the reaction of a compound of the formula (3) with a compound of the formula (2) preferably proceeds at temperatures of-100°C to 300°C, more preferably at temperatures of > 25°C and of ≥ 50°C and 65°C. Furthermore, a suitable pressure is established to ensure that the compound of the formula (3), is liquid or gaseous as required, and the compounds of the formulae (2) and (4) are gaseous, wherein pressures of 0.1 mbar to 2 bar, in particular of 1 mbar to 1 bar are conventionally used. Under these conditions, the intermediate of the first silazane cleavage or the final product obtained by the second silazane cleavage are in each case obtained in liquid form. In order to achieve a maximally quantitative conversion into the desired products, the silazane compound, in particular a compound of the formula (3), is preferably reacted with an excess of compounds of the formula (2) and/or a excess of compounds of the formula (4). Compounds of the formula (2) and/or compounds of the formula (4) are preferably introduced in an amount of at least 1.1 times, more preferably at least 1.2 times, still more preferably at least 1.5 times, and most preferably at least 2 times greater than the silazane compound. In a preferred embodiment of the method according to the invention, pressure and temperature are adjusted such that the educts (2) and (4) are in gaseous form, but the educt (3), intermediate and final product are in liquid form. In this mode of operation of the method, the intermediate or final product may straightforwardly be separated from the method in condensed form. Separation may, for example, proceed by crystallisation, condensation and/or the use of a solvent. The product is preferably separated and recovered from the equilibrium by condensation. The mode of operation of the method furthermore preferably proceeds in such a manner that secondary products, to the extent that any are formed, are removed from the reaction mixture. One secondary product often formed during the reaction is R3SiHal, for example Me3SiHal. Pressure and temperature are therefore suitably adjusted such that the partial pressure of a secondary product R3SiHal formed during the reaction is lower than the saturation vapour pressure thereof, such that the secondary product is thus in gaseous form. Such gaseous secondary products may be separated in straightforward manner, for example by partial condensation, distillation, pervaporation, gas permeation or adsorption. Isolation of the reaction product or separation of secondary products may advantageously proceed by means of phase separation between the condensate phase and gas phase, for example in an inertial separator or in a cyclone. In a preferred embodiment, the method according to the invention is carried out as a reactive distillation. It is furthermore preferred to convert one educt quantitatively in the liquid phase countercurrently with a second educt in the gaseous phase. Preferably, one or both reaction stages are carried out as gas-liquid reactions, wherein suitable reactors may be for example bubble columns, spray columns, packed columns, falling-film reactors or reactors with external recirculation. The compounds with the formulae (2) and (4) are preferably reacted in gaseous form. It is furthermore preferred to carry out the synthesis in a two- stage reaction process, in which both reaction stages proceed in the gas phase. In order to achieve maximally quantitative conversion of the feed materials into the target compounds, unreacted feed materials or educts are advantageously returned to the process. The invention in particular relates to a continuous mode of operation of two or more successive silazane cleavage reactions in a circuit of closed flow apparatuses without intermediate isolation or storage of the intermediate. The only secondary product to arise is R23SiCI or R33SiCI, which, by reaction with R1NH2, may be returned into the educt R23SiNR1SiR33. One particularly advantageous aspect of the method according to the invention is that no salts arise as secondary products. In a preferred embodiment of the invention, in the first stage, a compound of the formula (2), preferably SiHal4-xRx, reacts with a silazane compound, in particular a compound of the formula (3), preferably Me3SiNR1SiMe3, in the gas phase or in a gas phase-liquid phase reaction at temperatures of-100°C to 300°C, in particular of 25 to 100°C and preferably of ≥ 55°C to ≤ 65°C, and pressures in the reaction volume of 0.1 mbar to 2 bar, and specifically in each case under p/T conditions, under which the compound of the formula (2) is gaseous and the compound of the formula (3) is gaseous or liquid, but the saturation vapour pressure of the particular reaction product is exceeded and the latter is therefore condensed as a liquid, so being withdrawn from the homogeneous equilibrium and, once separated by a phase separator, fed into the next stage. In a second stage, the intermediate is then reacted with a compound of the formula (4) and specifically preferably under p/T conditions, under which the compound of the formula (4) is gaseous and the intermediate is liquid. The second stage is preferably carried out at temperatures of -100°C to +30°C. The invention is based on the observation that the described type of reaction may surprisingly be carried out with elevated selectivity even at elevated temperatures. According to the invention, this is preferably achieved by two measures: 1. An excess compound of the formula (2), preferably SiHal4-xRx, is always present in the reaction volume, such that the two-fold amination, for example to yield Me3Si-NR1-SiHal2-xRx-NR1-SiMe3 (x = 0.1) is suppressed. 2. The desired intermediate, for example Hal3-xRxSiNR1SiMe3 is efficiently drawn off as a liquid phase or removed from the gas phase by condensation and in this way an undesired further reaction to yield Hal3-xRxSiNR1SiRxHal3-x is stopped. If the difference in the boiling points of the feed material of the formula (2), for example SiHal4-xRx, and of the corresponding secondary product, for example Me3SiHal is sufficiently large, a condenser is located at the top of the reaction volume, on which the feed material of the formula (2), for example SiHal4-xRx, which has been added in excess, is separated and the secondary product, for example Me3SiHal, is allowed to pass through in gaseous form. The educt recovered after separation of the phases, for example SiHal4-xRx, is conveyed back into the reactor. In steady-state operation, fresh compounds of the formula (3), for example Me3SiNR1SiMe3l and of the formula (2), for example SiHal4-xRx, are then supplied to the reactor in the same amount per unit time as the secondary product, for example Me3SiHal, is removed from the reactor. If, on the other hand, the boiling points of the feed material of the formula (2), for example SiHal4-xRx, and of the secondary product, for example Me3SiHal, are very close to one another, the very different molar masses of these components (for example, molar mass of SiCI4: 169.9; molar mass of Me3SiCI: 108.6) may sensibly be exploited for the separation thereof. Suitable methods for this purpose are membrane methods using porous membranes or adsorption onto molecular sieves. In this case, such a suitable separation stage firstly adjoins the top of the reactor, in which the sub-stream enriched with educt, for example SiHal4-xRx, is condensed and returned to the process. Fresh educt, for example SiHal4-xRx is fed into the process in a molar quantity per unit time which corresponds to the cumulated quantity of discharged educt, for example SiHal4-xRx, and secondary product, for example Me3SiHal, while fresh compounds of the formula (3), for example Me3SiNR1SiMe3, are supplied to the reactor in the same amount per unit time as the secondary product, for example Me3SiHal, is removed from the reactor. The intermediate, for example Hal3-xRxSiNR1SiMe3, is introduced into the second reaction stage in gaseous or liquid form and reacted with an excess of compounds of the formula (4), for example BCI3. The pressure and temperature in the reactor are suitably adjusted such that the partial pressure of the secondary product, for example Me3SiHal, is lower than the saturation vapour pressure thereof. In particular, temperatures of-100°C to 300°C and pressures of 0.1 mbar to 2 bar satisfy the stated requirements for p/T conditions. Secondary product, for example Me3SiHal, and excess compounds of the formula (4), for example BCI3, are drawn off from the top of the reactor. The secondary product, for example Me3SiHal, is condensed and reused for the production of the starting materials of the formula (3), for example Me3SiNR1SiMe3. The educt of the formula (4), for example BCI3, is returned to the reactor. The final product is obtained in liquid form and may be discharged from the bottom of the reactor and, if necessary, purified by partial condensation, distillation or pervaporation. The method according to the invention may in particular be used for the production of compounds which comprise the structural feature X-N-Y, in which X and Y may in each case independently be B, Al, Ga, In, Si, Ge, P, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Fe or Zn. It is particularly preferably used for production of a compound which has the formula (1) RxHal3-xSi-NR1- BRyHal2-y, in which Hal in each case independently means CI, Br or I, R in each case independently represents a hydrocarbon residue with 1 to 20 C atoms or hydrogen, R1 represents a hydrocarbon residue with 1 to 20 C atoms or hydrogen, x = 0, 1 or 2 and y = 0 or 1. The desired products are preferably produced in a two-stage process. The compounds according to the formula (1) are for example produced by reacting a hexamethyldisilazane component (HMDS) Me3SiNR1SiMe3 in succession in any desired order with a silane component SiHal4-xRx and a borane component BHal3-yRy. In the first step, the silane component, which is introduced in a gaseous state, is preferably caused to react in the gas phase or a gas phase-liquid phase reaction continuously or in portions, with or without a carrier gas, with the hexamethyldisilazane component, which is introduced in a liquid or gaseous state of aggregation. The intermediate formed is in turn preferably further reacted in the second step with the borane component in excess in an inert solvent, preferably in the gas phase or more preferably in pure condensed phase. Alternatively, the intermediate may be caused to react in a liquid state of aggregation with the borane component which is present in a gaseous state. Depending on p/T conditions, the target compound is obtained in pure form or mixed with the secondary product Me3SiCI and the excess borane component and may be isolated with a phase separator. Using this reaction pathway, it is possible inter alia to produce the compounds MeCI2SiNHBCI2 (MADB) (1a), CI3SiNHBCI2 (TADB) (1b), (CH3)2CISiNHBCI2 (DADB), CI3SiNCH3BCI2 (DMTA) or CH3CI2SiNCH3BCI2 (DDMA) in pure form. In the case of MADB, methyltrichlorosilane, which is introduced in a gaseous state, and hexamethyldisilazane, which is introduced in a gaseous or liquid state of aggregation, are caused to react in the gas phase or in a gas phase-liquid phase reaction. In the case of TADB, tetrachlorosilane is used instead of methyltrichlorosilane, the reaction being carried out in analogous manner. The intermediates obtained are respectively MeCI2SiNHSiMe3 and CI3SiNHSiMe3, which are in each case reacted in the gas phase or preferably in condensed form with gaseous trichloroborane. In the formula RxHal3-xSi-NR1-BRyHal2-y (1), the residues R and R1 may in each case independently mean hydrogen or a hydrocarbon residue with 1 to 20 C atoms, preferably with 1 to 10 C atoms. A hydrocarbon residue is here a residue which is formed from the elements carbon and hydrogen. According to the invention, hydrocarbon residues may be branched or unbranched, saturated or unsaturated. The hydrocarbon residue may also contain aromatic groups, which may in turn be substituted with hydrocarbon residues. Examples of preferred hydrocarbon residues are for example unbranched saturated hydrocarbon residues, such as for instance C1 to C20 alkyl, in particular methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl and n-decyl. The residues R and/or R1 may, however, also comprise branched saturated hydrocarbon residues, in particular branched C3 to C20 alkyls, such as for instance i-propyl, i-butyl, t- butyl and further branched alkyl residues. In one embodiment, the residues R and/or R1 comprise one or more olefinically unsaturated groups. Examples of such residues are vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, pentadienyl, heptadienyl, octadienyl, nonadienyl and decadienyl. The residues R and/or R1 may also contain an alkyne group, thus a C=C bond. In a further embodiment, at least one residue R and/or R1, preferably all the residues R and/or R1, contain(s) an aromatic group, in particular an aromatic group with 5 to 10 C atoms, in particular 5 or 6 C atoms, such as for instance a phenyl group or an aromatic group, in particular a phenyl group, substituted with a hydrocarbon, in particular a C1 to C10 hydrocarbon, such as for instance methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl or propylphenyl. Including the substituents, the aromatic residue preferably comprises 5 to 20, in particular to 10 C atoms. The hydrocarbon residues R and R1 may here in each case mutually independently be varied. Preferably, at least one residue R and/or R1 and in particular all the residues R and/or R1 comprise(s) hydrogen, a C1 to C20 alkyl group, in particular a C1 to C6 alkyl group, a phenyl group, a vinyl group or an allyl group or a hydrocarbon residue with 1 to 3 C atoms, in particular methyl, ethyl or propyl and particularly preferably methyl. The residue Hal denotes a halogen atom and in particular means CI, Br or I, it being preferred for at least one Hal residue and preferably all Hal residues to mean CI. The invention is described in greater detail by the attachec ACCOMPANYING Figures 1-4 and the following Examples. Figures 1-4 are schematic diagrams of variants of the production plant for the two-stage method according to the present invention. Examples Example 1: Synthesis of MADB (1a) Figure 1 shows the method flow chart according to one embodiment of the invention. The procedures in reaction stages I and II are independent of one another and are described sequentially. MeSiCL3 is apportioned from the temperature-controlled holding vessel 1 and HMDS from the temperature-controlled holding vessel 2 either pure or in an inert carrier gas stream, for example N2, He, Ar, CO2, into the reactor 3. The feed materials are both jointly introduced pointwise, or both spatially distributed or one pointwise and one spatially distributed into the reactor 3 of the first reaction stage. Thanks to the nature of apportioning and flow control, a stoichiometric excess of MeSiCI3 to HMDS of at least 2:1 is ensured throughout the entire reaction chamber. Reactor temperature is controlled with the assistance of an external heat exchanger 3a to a temperature between -100°C and 300°C, in particular between 25°C and 100°C. The total pressure in the reactor 3 is between 0.1 mbar and 2 bar. Pressure and temperature are here adjusted relative to one another such that the partial pressures of the feed compounds MeSiCI3 and HMDS are below their respective saturation vapour pressures, but the partial pressure of the intermediate MeCl2SiNHSiMe3 exceeds its saturation pressure. Under these conditions, the intermediate condenses, is discharged from the reaction volume via a phase separator 4 and directly supplied to the second reaction stage, alternatively it may be held in a buffer vessel 5. At the top of the reactor 3, the feed material MeSiCl3 is condensed from the volatile components on a heat exchanger 6 and separated by means of a phase separator 7 from the secondary product Me3SiCI. The temperature of the heat exchanger 6 is adjusted such that, at the given pressure, MeSiCl3 exceeds its saturation vapour pressure, but Me3SiCI is below its saturation vapour pressure. MeSiCI3 is recirculated into the reactor. In steady-state operation, MeSiCI3 and HMDS are replenished from the storage vessels 1_ and 2 in the same molar quantity per unit time as the Me3SiCI is removed from the reactor. The intermediate from the first reaction stage is reacted in the second reaction stage with an excess of BCI3, which is supplied from the temperature-controlled holding vessel 8. The second reaction stage may be of an analogous structure to the first stage, the reactor temperature being adjusted between -100°C and +30°C and the pressure set such that at least BCI3 is in gaseous form, or may be carried out according to the prior art (DE 4 107 108, DE 10 045 428, DE 10 104 536). The final product is purified by phase separation. The phase separators 4 and 7 may function by the principle of mechanical separation, for example inertial separators or cyclones. Thermal or physico- chemical separation methods may, however, also be used. Distillation/rectification or pervaporation may in particular be considered. The product yield of MADB amounts over both stages to at least 76% relative to the introduced HMDS. The product is characterised by mass spectrometry and nuclear magnetic resonance spectroscopy. MS (70 eV): m/z = 196 (M+-CH3), 174 (M+-HCI), 158 (M+-HCI-CH3), 138 (M+-2HCI), 1H- NMR: δ= 0.47; 0.49; 13C-NMR: 5= 6.3; 9.3; 128.4; 11B-NMR: 5= 36.4; 41.8. Example 2: Synthesis of MADB (1a) The boiling points of the educts, the intermediate, the secondary product and the final product are in a favourable ratio to one another, such that MADB may be synthesised by reactive distillation. Figure 2 shows the diagram of this process variant. The process proceeds in a vacuum column 4. The educts of the first reaction stage are introduced into the rectification section together or at different positions 1 and 2. The highly volatile secondary product MeSiCl3 is enriched towards the top of the column and the intermediate Cl3SiNHSiMe3 towards the exhausting section of the column. BCI3 is separately introduced into the column via the inlet 3. The product is collected at the bottom of the column. Example 3: Synthesis of TADB (1b) Preparation of compound (1b) proceeds in analogous manner to the preparation of compound (1a) in Example 1, but using SiCl4 and HMDS instead of MeSiCI3 and HMDS as the educts. At the top of the reactor 3, unreacted SiCI4 and secondary product Me3SiCI leave the reaction chamber together in gaseous form, as they have the same vaporisation temperature. The SiCI4/Me3SiCI mixture is accordingly separated by means of a suitable separation stage 7 (membrane method with porous membranes or adsorption onto molecular sieves) and the sub-stream enriched with SiCI4 is condensed in a total condenser 6 and recirculated into the first reaction stage. In steady-state operation, SiCl4 and HMDS are resupplied to the process from the storage vessels 1 and 2 in a molar quantity per unit time which corresponds to the cumulated quantity of Me3SiCI and discharged SiCl4. The product yield of TADB amounts over both stages to at least 85% relative to the introduced HMDS. The product is characterised by mass spectrometry and nuclear magnetic resonance spectroscopy. MS (70 eV): m/z = 231 (M+), 196 (M+-CI), 160 (M+-CI -HCI); 1H-NMR: δ= 4.41; 11B-NMR: δ= 35.7; 29Si- NMR: δ=-23.7. Figure 3 shows the method flow chart according to the described embodiment of the invention. Example 4: Synthesis of TADB (1b) Preparation of compound (1b) proceeds in analogous manner to the preparation of compound (1a) in Example 2 (Figure 2), but using SiCl4 and HMDS instead of MeSiCI3 and HMDS as the educts. Moreover, the educts for the first reaction stage are preferably introduced into the rectification section at different positions 1 and 2. Due to its higher boiling point, the feed material HMDS is introduced into the rectification section above the feed material SiCl4- Example 5: Synthesis of TADB (1b) Figure 4 shows the method flow chart according to an embodiment of the invention. The procedures in reaction stages (I) and (II) are independent of one another and are described sequentially. SiCl4, is apportioned from a temperature-controlled holding vessel 1 either pure or in an inert carrier gas stream, for example N2, He, Ar, CO2l into the lower part of the reactor of the first reaction stage 2 (for example falling-film reactor). HMDS is apportioned in liquid form from the storage vessel 3 into the top of the reactor and reacts countercurrently with gaseous SiCI4. The molar flow rates of the two reactants are controlled such that a stoichiometric excess of SiCl4 to HMDS of 1.2 to 1.5 is maintained in the reaction chamber. Reactor temperature is controlled between -50°C and 200°C with the assistance of a external heat exchanger 2a. The total pressure in the reactor 2 is between 1 mbar and 1 bar. Pressure and temperature are here adjusted relative to one another such that the partial pressures of the feed compound SiCI4 and of the secondary product MeSiCI3 are below their respective saturation vapour pressures, but HMDS and the intermediate CI3SiNHSiMe3 are in liquid form. This is the case, for example, with the combination 60°C / 300 mbar. The intermediate is discharged in liquid form at the bottom of the falling-film reactor and directly supplied to the second reaction stage. Alternatively, the intermediate may be held in a buffer vessel 5. At the top of the reactor 2, unreacted SiCl4, and secondary product Me3SiCI leave the reaction chamber together in gaseous form, as they have virtually the same vaporisation temperature. The further treatment thereof proceeds as described in Example 3. The intermediate from the first reaction stage is reacted in the second reaction stage with an excess (1.1-1.5 times) of BCI3, which is supplied from the temperature-controlled holding vessel 8. The second reaction stage may be of an analogous structure to the first, but may also take the form of a plate column, temperature and pressure conditions being adjusted relative to one another such that feed material BCI3 is in gaseous form and the secondary product Me3SiCI is in gaseous or liquid form, while the intermediate stage CI3SiNHSiMe3 and the final product CI3SiNHBCI2 (TADB) are in liquid form. Excess BCI3 and the secondary product Me3SiCI are discharged in gaseous form from the top of the reactor and separated with a phase separator. Recovered BCI3 is supplied, for example, to the holding vessel 8, while Me3SiCI is recirculated into the production of the feed material HMDS. The final product is purified by phase separation and optionally separated from the secondary product Me3SiCI. The phase separators 4 and 9 may function by the principle of mechanical separation, for example inertial separators or cyclones. Thermal or physico- chemical separation methods may, however, also be used. Distillation/rectification or pervaporation may in particular be considered. The product yield of TADB amounts over both stages to at least 84% relative to the introduced HMDS. The product is characterised by mass spectrometry and nuclear magnetic resonance spectroscopy (see Example 3). 1. A sifazane cleavage method comprising reacting a silazane compound with a cleaving reagent, wherein at least one of the silazane compound and the cleaving reagent is introduced in gaseous form and wherein said method is carried out continuously. 2. A method as claimed in claim 1, wherein one educt in the liquid phase is reacted with a second educt in the gaseous phase. 3. A method as claimed in claim 1, wherein all the educts are introduced in gaseous form. 4. A method as claimed in any one of the preceding claims, wherein a silazane compound is reacted with at least one compound of the formula (2) selected from BHal3-xRx, AlHal3-xRx, GaHal3-xRx, InHal3-xRx, SiHal4-yRy, GeHal4-yRy, PHal3-xRx, PHal5-zRz, TiHal4-yRy, ZrHal4-yRy, VHal3-xRx, VHal4-yRy, NbHal5-zRz, TaHal5-zRz, CrHal3-xRx, MoHal4-yRy, MoHal5-zRz, WHal6-zRz, FeHal3-xRx or ZnCl2 in which x = 0 or 1, y = 0, 1 or 2 and z = 0,1, 2 or 3, Hal is selected from F, CI, Br and I, and R represents hydrogen or a hydrocarbon residue with 1 to 20 C atoms. 5. A method as claimed in any one of the preceding claims, wherein the target product of the reaction is removed from the reaction mixture. 6. A method as claimed in any one of the preceding claims, wherein one of the educts is introduced in excess. 7. A continuous method comprising silazane cleavage as claimed in one of claims 1 to 6 for the production of a compound which comprises the structural feature N-Y, in which Y is in each case independently selected from B, Al, Ga, In, Si, Ge, P, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Fe or Zn, wherein a silazane compound is reacted with a compound of the formula (2) selected from BHal3-xRx, AlHal3-xRx, GaHal3-xRx, InHal3-xRx, SiHal4-yRy, GeHal4-yRy, PHals-xRx, PHal5-zRz, TiHal4-yRy, ZrHal4-yRy, VHal3-xRx, VHal4-yRy, NbHal5-zRz, TaHal5-zRz, CrHal3-xRx, MoHal4-yRy, MoHal5-zRz, WHal5-zRz, FeHal3-xRx or ZnCI2 in which x = 0 or 1, y = 0, 1 or 2 and z = 0, 1, 2 or 3, Hal is selected from F, CI, Br and I, and R represents hydrogen or a hydrocarbon residue with 1 to 20 C atoms. 8. A continuous method comprising two silazane cleavage reactions as claimed in any one of claims 1 to 6 for the production of a compound which comprises the structural feature X-N-Y, in which X and Y are in each case independently selected from B, Al, Ga, In, Si, Ge, P, Ti, Zr, V, Nb, Ta Cr, Mo, W, Fe or Zn, comprising the steps reacting a compound of the formula (3) R23SiNR1Si R33, in which R2 and R3 in each case mutually independently represent a hydrocarbon residue with 1-20 carbon atoms and R1 represents hydrogen or a hydrocarbon residue with 1-20 C atoms, in succession in any desired order with a compound of the formula (2) selected from BHal3-xRx, AlHal3-xRx, GaHal3-xRx, InHal3-xRx, SiHal4-yRy, GeHal4-yRy, PHal3-xRx PHal5-zRz, TiHal4-yRy, ZrHal4-yRy, VHal3-xRx, VHal4-yRy, NbHal5-zRz, TaHal5-zRz, CrHal3-xRx, MoHal4-yRy, MoHal5-zRz, WHal6-zRz, FeHl3-xRx or ZnCI2 in which x = 0 or 1, y = 0, 1 or 2 and z = 0, 1, 2 or 3, Hal is selected from F, CI, Br and I, and R represents hydrogen or a hydrocarbon residue with 1 to 20 C atoms, and a compound of the formula (4) selected from BHal3-xRx, AlHal3-xRx, GaHal3-xRx, InHal3-xRx, SiHal4-yRy, GeHal4-yRy, PHal3-yRx, PHals5-zRz, TiHal4-yRy, ZrHal4-yRy, VHal3-xRx, VHal4-yRy, NbHal5-zRz, TaHal5-zRz, CrHal3-xRx, MoHal4-yRy, MoHal5-zRz, WHal6-zRz, FeHal3-xRx or ZnCI2 in which x = 0 or 1, y = 0, 1 or 2, z = 0, 1, 2 or 3, Hal is selected from F, CI, Br and I, and R represents hydrogen or a hydrocarbon residue with 1-20 C atoms. 9. A method as claimed in any one of the preceding claims, wherein the product formed is a molecular single component precursor for non-oxide ceramics. 10. A method as claimed in any one of the preceding claims, wherein a compound of the formula (1) Rx Hal3-xSi-NR1-BRyHal2-y is produced, wherein SiHal4-yRy is used as the compound of the formula (2) and BHal3-xRx is used as the compound of the formula (4). 11. A method as claimed in any one of the preceding claims, wherein the reaction is carried out at temperatures of-100°C to 300°C and/or a pressure of 0.1 mbar to 2 bar. 12. A method as claimed in any one of the preceding claims, wherein pressure and temperature are adjusted such that the educts are in gaseous form, but the intermediate and final product are in liquid form. 13. A method as claimed in any one of the preceding claims, wherein the reaction with compounds of the formula (2) is carried out at a temperature of ≥ 25°C, in particular ≥ 50°C. 14. A method as claimed in any one of the preceding claims, wherein the silazane compound is reacted with an excess of compounds of the formula (2). 15. A method as claimed in any one of the preceding claims, wherein R3SiHal is separated as secondary product from the method. 16. A method as claimed in any one of the preceding claims, wherein pressure and temperature are adjusted such that the partial pressure of a secondary product of the formula (5) formed during the reaction R3SiHal is lower than the saturation vapour pressure thereof, in which Hal in each case independently means CI, Br or I, R in each case independently represents a hydrocarbon residue with 1 to 20 C atoms or hydrogen, x = 0, 1 or 2 and y = 0 or 1. 17. A method as claimed in any one of the preceding claims, wherein compound of the formula (3) is reacted first with a compound of the formula (2) and thereafter in a further stage with a compound of the formula (4). 18. A method as claimed in claim 8, wherein the reaction of the compound of the formula (3) with the compound of the formula (2) is carried out under pressure and temperature conditions, under which the educts are in gaseous form and the intermediate condenses as a liquid, the intermediate being separated in liquid form. 19. A method as claimed in claim 18, wherein the reaction of the compound of the formula (3) with the compound of the formula (2) is carried out under pressure and temperature conditions, under which the educt of the formula (3) is in gaseous form, while the educt of the formula (2) and the intermediate are in liquid form. 20. A method as claimed in any one of the preceding claims, wherein the compound CH3CI2SiNHBCI2 (MADB), CI3SiNHBCI2 (TADB), (CH3)2CISiNHBCI2 (DADB), CI3SiNCH3BCI2 (DMTA) or CH3CI2SiNCH3BCI2 (DDMA) is produced. ABSTRACT Title: Continuous silazane cleavage method. A silazane cleavage method comprising reacting a silazane compound with a cleaving reagent, wherein at least one of the silazane compound and the cleaving reagent is introduced in gaseous form and wherein said method is carried out continuously.

Full Text

Continuous silazane cleavage method
Description
The present invention relates to a continuous silazane cleavage method, in
particular for the production of molecular precursors for non-oxide inorganic
ceramics.
Silazane cleavage reactions which are carried out batchwise have already
been described in the prior art (Metallo-organicheskaya Khimiya (1989), 2(3),
701-2, Kalikhman, I.D. et al.; Journal of Organometallic Chemistry (1989),
361(2), 147-55, Kalikhman, I.D. et al.; Zhurnal Obshchei Khimii (1981),
51(8), 1824-9, Sheludyakov, V.D. et al.).
Ceramics prepared from the anionic components C and N together with 2 to
4 further elements such as B, Al, Ga, In, Si, Ge, P, Ti, Zr, V, Nb, Ta, Cr, Mo,
W, Fe or Zn having a cationic function are of particular interest. Such
ceramics, for example consisting of Si, B, N and C, are distinguished by
excellent thermal, mechanical and chemical resistance and, in terms of their
combination of all applicational properties, are distinctly superior to
competing materials, for example for use in heat engines. A prerequisite for
achieving these advantageous properties is the creation of a network with a
regular alternation of elements with an anionic and cationic function, the
latter homogeneously distributed over zones of above 1 to 2 nm.
Such prerequisites may be achieved by the synthesis and provision of
molecular single component precursors, which contain the particular desired
combination of cationic components linked to one another via nitrogen.
These molecular precursors are then polymerised and finally ceramised by
pyrolysis. Since the polymeric intermediate stages may be processed using
any polymer processing method, an unusually wide range of forms of use is
accessible, such as for example fibres, films, infiltrates, coatings and
mouldings. The potential of this new family of materials for the production of

fibre-reinforced ceramic composites is of particular significance. Unequalled
properties at elevated temperatures in air and with simultaneous mechanical
loading are the guarantee of potential applications. Penetration into areas
occupied by metallic and conventional ceramic materials is desirable due to
the numerous technical advantages, but only possible if an inexpensive
production process is available.
The review article "Amorphous Multinary Ceramics in the Si-B-N-C System"
(M. Jansen et al., Struct. Bond. 2002, 101, 137) and DE41 07 108A1, DE
100 45 427 A1, DE 100 45 428 A1 and 101 04 536 A1 describe syntheses
for the Si/B/N/C subsystem for the variants of the molecular scaffold for a
single component precursor of the formula (1) RxHal3-xSiNR1-BRyHal2-y
wherein R in each case independently represents a hydrocarbon residue
with 1 to 20 C atoms, Hal in each case independently means CI, Br or I, R1 in
each case independently represents a hydrocarbon residue with 1 to 20 C
atoms or hydrogen, x = 0, 1 or 2 and y = 0 or 1.
A feature which is common to the above-described methods is that the
particular target molecule is synthesised in batch mode starting from Me3Si-
NR1SiMe3 by two successive silazane cleavage reactions, firstly with
SiHal4-xRx, then with BHal3.yRy.

These are laboratory syntheses which cannot straightforwardly be carried out
as environmentally and economically optimised production methods on an
industrial scale.
The following may in particular be problematic:
1. Reaction times for the first silazane cleavage are between 20 and 48
hours, for the second approx. 12 hours per batch. Satisfactory space-time
yields thus cannot be achieved via this route.
2. If reaction temperatures are increased, selectivity declines and undesired
secondary products such as RxHal3-xSi-NR1-SiHal3-xRx or Me3Si-NR1-
SiHal2-xRx-NR1-SiMe3 may be formed.
3. Large excesses of costly feed materials have hitherto been necessary, the
costs of which impair the economic viability of the method.
4. Synthesis by the "batch" method is comparatively uneconomic, since each
reaction batch is preceded by a time-consuming and costly provision of an
inert atmosphere in the reaction apparatus.
5. High costs are generated by the necessary cooling during synthesis and
by the isolation and purification of the product by distillation processes.
DE100 45 428A1 describes an alternative preparative route to yield the
above defined single component precursors, according to which an amine
component R1NH2 is reacted in succession with a silane component
SiHal4-xRx and a borane component BHal3-yRy:

In this sequence of two successive aminolysis reactions, the formation of
difficult to separate saline hydrochlorides, which inevitably occurs in both
steps, is disadvantageous and additionally considerably diminishes product
yield relative to the introduced material. Nonetheless, this approach has
made it possible to achieve a continuous production method, in which the
reactor is cycled between a production phase and a regeneration phase
(stripping of hydrochlorides) (DE 102 28 990 A1).
While the described method already yields good results, it still exhibits
disadvantages from a technical and economic standpoint:
1. The space-time yield is reduced by the intermittent mode of operation.
The only remedy is to install a parallel reactor (so increasing capital
investment).
2. Half of the amine starting component and half of the silylamine
intermediate stage are bound as hydrochlorides and discharged during
the regeneration cycle. This considerably reduces the yield of final product
relative to the valuable feed materials.
3. The target products require elaborate isolation and purification.
4. Residues of intermediate and final product are pyrolysed during thermal
stripping and accordingly result in reactor fouling over long-term operation.
Many compounds of interest and in particular molecular single component
precursors for non-oxide ceramics may be produced by silazane cleavage.
Hitherto known batch methods, however, exhibit the disadvantages
discussed above. It was accordingly an object of the present invention to
provide a method for cleaving silazane compounds which at least partially
overcomes the disadvantages of the prior art.
A further object of the present invention was to provide an efficient, generally
applicable method for the production of single component precursors for
non-oxide ceramics which should in particular satisfy the following
requirements:
- it should be possible to carry out the method continuously, without separate
isolation or storage of the intermediate stage.
- product yield should be optimal, such that the feed materials are converted
as completely as possible into the product.

The invention relates to a method for cleaving silazane compounds, which is
characterised in that it is carried out continuously. It has surprisingly been
found that silazane cleavage may be carried out continuously, so making it
possible to overcome the above-stated disadvantages with regard to a poor
space-time yield.
Silazanes are silicon-nitrogen compounds which comprise an Si-N bond.
Element-N compounds can be synthesised by silazane cleavage.
It has furthermore been found according to the invention that a continuous
mode of operation of the method is in particular advantageous and possible
if at least one of the educts introduced for silazane cleavage is used in
gaseous form. The silazane or the cleaving reagent or both may here be
introduced in gaseous form. In a preferred embodiment, all the educts are
introduced in gaseous form and the reaction proceeds in the gas phase. In a
further preferred embodiment, at least one educt is introduced in gaseous
form and at least one other educt is introduced in liquid form. When this
approach is used, the method is advantageously performed countercurrently,
whereby it is possible to achieve conversion which is virtually quantitative or
even quantitative. When the reaction is carried out in this manner, at least
one reaction stage advantageously takes the form of a gas-liquid reactor, for
example a bubble column, spray column, packed column, falling-film reactor
or reactor with external recirculation.
A further improvement of the continuous method according to the invention
may be achieved by removing the target product and/or undesired secondary
products from the reaction mixture and thus from the equilibrium. The target
product may be isolated from the remaining components of the reaction
mixture for example by crystallisation, condensation and/or using a solvent.
Secondary products, in particular highly volatile secondary products, are
preferably removed from the reaction mixture by partial condensation,
distillation, pervaporation, gas permeation or adsorption. Phase separation
between the condensate phase and gas phase preferably proceeds in an
inertial separator or in a cyclone. Using the continuous mode of operation of
the method according to the invention, it is in particular possible to achieve
elevated selectivity with regard to the desired target products. Selectivity may
further be ensured by carrying out the reaction with one of the educts in

in which x = 0 or 1, y = 0, 1 or 2 and z = 0, 1, 2 or 3, Hal is selected from F,
CI, Br and I, and R represents hydrogen or a hydrocarbon residue with 120 C
atoms,
and a compound of the formula (4) selected from
BHal3-xRx, AIHal3-xRx, GaHal3-xRx, lnHal3-xRx, SiHal4-yRy, GeHal4-yRy,
PHal3-xRx, PHal5-zRz, TiHal4-yRy, ZrHal4-yRy, VHal3.xRx, VHal4-yRy, NbHal5-zRz,
TaHal5-zRz, CrHal3-xRx, MoHal4-yRy, MoHal5-zRz, WHal6-zRz, FeHal3-xRx or
ZnCI2
in which x = 0 or 1, y = 0, 1 or 2, z = 0, 1, 2 or 3, Hal is selected from F, CI,
Br and I, and R represents hydrogen or a hydrocarbon residue with 1-20 C
atoms. In this embodiment, two silazane cleavage reactions are carried out.
In these two reactions, the compounds of the formulae (3) and (4) are
preferably present in gaseous form.
It has surprisingly been found the method for the production of molecular
single component precursors for non-oxide ceramics may be carried out
continuously. The reaction of the silazane compound with a compound of the
formula (2) preferably proceeds in the gas phase. Alternatively, one of the
two reactants may be introduced in the form of a liquid. In this case, the
compound of the formula (3) is preferably present in the liquid phase and the
compound of the formula (2) in the gaseous phase. The product of silazane
cleavage is obtained in liquid form, whereby the desired products may be
produced inexpensively and on a large scale. The method according to the
invention for the production of compounds with the structural feature X-N-Y,
in particular of compounds with the formula (1) RxHal3-xSi-NR1BRyHal2-y
proceeds via a two-fold silazane cleavage from R23SiNR1SiR33 (3).
In formula (3), R2 and R3 may preferably in each case independently mean
an alkyl and/or aryl residue with 1-7 C atoms, preferably a methyl residue.
The silazane cleavage according to the invention and in particular the
reaction of a compound of the formula (3) with a compound of the formula
(2) preferably proceeds at temperatures of-100°C to 300°C, more preferably
at temperatures of > 25°C and of ≥ 50°C and 65°C. Furthermore, a suitable pressure is established to ensure that the
compound of the formula (3), is liquid or gaseous as required, and the

compounds of the formulae (2) and (4) are gaseous, wherein pressures of
0.1 mbar to 2 bar, in particular of 1 mbar to 1 bar are conventionally used.
Under these conditions, the intermediate of the first silazane cleavage or the
final product obtained by the second silazane cleavage are in each case
obtained in liquid form.
In order to achieve a maximally quantitative conversion into the desired
products, the silazane compound, in particular a compound of the formula
(3), is preferably reacted with an excess of compounds of the formula (2)
and/or a excess of compounds of the formula (4). Compounds of the formula
(2) and/or compounds of the formula (4) are preferably introduced in an
amount of at least 1.1 times, more preferably at least 1.2 times, still more
preferably at least 1.5 times, and most preferably at least 2 times greater
than the silazane compound.
In a preferred embodiment of the method according to the invention,
pressure and temperature are adjusted such that the educts (2) and (4) are
in gaseous form, but the educt (3), intermediate and final product are in liquid
form. In this mode of operation of the method, the intermediate or final
product may straightforwardly be separated from the method in condensed
form. Separation may, for example, proceed by crystallisation, condensation
and/or the use of a solvent. The product is preferably separated and
recovered from the equilibrium by condensation.
The mode of operation of the method furthermore preferably proceeds in
such a manner that secondary products, to the extent that any are formed,
are removed from the reaction mixture. One secondary product often formed
during the reaction is R3SiHal, for example Me3SiHal. Pressure and
temperature are therefore suitably adjusted such that the partial pressure of
a secondary product R3SiHal formed during the reaction is lower than the
saturation vapour pressure thereof, such that the secondary product is thus
in gaseous form. Such gaseous secondary products may be separated in
straightforward manner, for example by partial condensation, distillation,
pervaporation, gas permeation or adsorption.
Isolation of the reaction product or separation of secondary products may
advantageously proceed by means of phase separation between the

condensate phase and gas phase, for example in an inertial separator or in a
cyclone.
In a preferred embodiment, the method according to the invention is carried
out as a reactive distillation.
It is furthermore preferred to convert one educt quantitatively in the liquid
phase countercurrently with a second educt in the gaseous phase.
Preferably, one or both reaction stages are carried out as gas-liquid
reactions, wherein suitable reactors may be for example bubble columns,
spray columns, packed columns, falling-film reactors or reactors with external
recirculation.
The compounds with the formulae (2) and (4) are preferably reacted in
gaseous form. It is furthermore preferred to carry out the synthesis in a two-
stage reaction process, in which both reaction stages proceed in the gas
phase.
In order to achieve maximally quantitative conversion of the feed materials
into the target compounds, unreacted feed materials or educts are
advantageously returned to the process.
The invention in particular relates to a continuous mode of operation of two
or more successive silazane cleavage reactions in a circuit of closed flow
apparatuses without intermediate isolation or storage of the intermediate.
The only secondary product to arise is R23SiCI or R33SiCI, which, by reaction
with R1NH2, may be returned into the educt R23SiNR1SiR33. One particularly
advantageous aspect of the method according to the invention is that no
salts arise as secondary products.
In a preferred embodiment of the invention, in the first stage, a compound of
the formula (2), preferably SiHal4-xRx, reacts with a silazane compound, in
particular a compound of the formula (3), preferably Me3SiNR1SiMe3, in the
gas phase or in a gas phase-liquid phase reaction at temperatures of-100°C
to 300°C, in particular of 25 to 100°C and preferably of ≥ 55°C to ≤ 65°C,
and pressures in the reaction volume of 0.1 mbar to 2 bar, and specifically in
each case under p/T conditions, under which the compound of the formula

(2) is gaseous and the compound of the formula (3) is gaseous or liquid, but
the saturation vapour pressure of the particular reaction product is exceeded
and the latter is therefore condensed as a liquid, so being withdrawn from
the homogeneous equilibrium and, once separated by a phase separator,
fed into the next stage.
In a second stage, the intermediate is then reacted with a compound of the
formula (4) and specifically preferably under p/T conditions, under which the
compound of the formula (4) is gaseous and the intermediate is liquid. The
second stage is preferably carried out at temperatures of -100°C to +30°C.
The invention is based on the observation that the described type of reaction
may surprisingly be carried out with elevated selectivity even at elevated
temperatures. According to the invention, this is preferably achieved by two
measures:
1. An excess compound of the formula (2), preferably SiHal4-xRx, is always
present in the reaction volume, such that the two-fold amination, for
example to yield Me3Si-NR1-SiHal2-xRx-NR1-SiMe3 (x = 0.1) is suppressed.
2. The desired intermediate, for example Hal3-xRxSiNR1SiMe3 is efficiently
drawn off as a liquid phase or removed from the gas phase by
condensation and in this way an undesired further reaction to yield
Hal3-xRxSiNR1SiRxHal3-x is stopped.
If the difference in the boiling points of the feed material of the formula (2),
for example SiHal4-xRx, and of the corresponding secondary product, for
example Me3SiHal is sufficiently large, a condenser is located at the top of
the reaction volume, on which the feed material of the formula (2), for
example SiHal4-xRx, which has been added in excess, is separated and the
secondary product, for example Me3SiHal, is allowed to pass through in
gaseous form. The educt recovered after separation of the phases, for
example SiHal4-xRx, is conveyed back into the reactor. In steady-state
operation, fresh compounds of the formula (3), for example Me3SiNR1SiMe3l
and of the formula (2), for example SiHal4-xRx, are then supplied to the
reactor in the same amount per unit time as the secondary product, for
example Me3SiHal, is removed from the reactor.

If, on the other hand, the boiling points of the feed material of the formula (2),
for example SiHal4-xRx, and of the secondary product, for example Me3SiHal,
are very close to one another, the very different molar masses of these
components (for example, molar mass of SiCI4: 169.9; molar mass of
Me3SiCI: 108.6) may sensibly be exploited for the separation thereof.
Suitable methods for this purpose are membrane methods using porous
membranes or adsorption onto molecular sieves. In this case, such a
suitable separation stage firstly adjoins the top of the reactor, in which the
sub-stream enriched with educt, for example SiHal4-xRx, is condensed and
returned to the process. Fresh educt, for example SiHal4-xRx is fed into the
process in a molar quantity per unit time which corresponds to the cumulated
quantity of discharged educt, for example SiHal4-xRx, and secondary product,
for example Me3SiHal, while fresh compounds of the formula (3), for
example Me3SiNR1SiMe3, are supplied to the reactor in the same amount
per unit time as the secondary product, for example Me3SiHal, is removed
from the reactor.
The intermediate, for example Hal3-xRxSiNR1SiMe3, is introduced into the
second reaction stage in gaseous or liquid form and reacted with an excess
of compounds of the formula (4), for example BCI3. The pressure and
temperature in the reactor are suitably adjusted such that the partial
pressure of the secondary product, for example Me3SiHal, is lower than the
saturation vapour pressure thereof. In particular, temperatures of-100°C to
300°C and pressures of 0.1 mbar to 2 bar satisfy the stated requirements for
p/T conditions. Secondary product, for example Me3SiHal, and excess
compounds of the formula (4), for example BCI3, are drawn off from the top
of the reactor. The secondary product, for example Me3SiHal, is condensed
and reused for the production of the starting materials of the formula (3), for
example Me3SiNR1SiMe3. The educt of the formula (4), for example BCI3, is
returned to the reactor. The final product is obtained in liquid form and may
be discharged from the bottom of the reactor and, if necessary, purified by
partial condensation, distillation or pervaporation.
The method according to the invention may in particular be used for the
production of compounds which comprise the structural feature X-N-Y, in
which X and Y may in each case independently be B, Al, Ga, In, Si, Ge, P,
Ti, Zr, V, Nb, Ta, Cr, Mo, W, Fe or Zn. It is particularly preferably used for

production of a compound which has the formula (1) RxHal3-xSi-NR1-
BRyHal2-y, in which Hal in each case independently means CI, Br or I, R in
each case independently represents a hydrocarbon residue with 1 to 20 C
atoms or hydrogen, R1 represents a hydrocarbon residue with 1 to 20 C
atoms or hydrogen, x = 0, 1 or 2 and y = 0 or 1.
The desired products are preferably produced in a two-stage process. The
compounds according to the formula (1) are for example produced by
reacting a hexamethyldisilazane component (HMDS) Me3SiNR1SiMe3 in
succession in any desired order with a silane component SiHal4-xRx and a
borane component BHal3-yRy. In the first step, the silane component, which is
introduced in a gaseous state, is preferably caused to react in the gas phase
or a gas phase-liquid phase reaction continuously or in portions, with or
without a carrier gas, with the hexamethyldisilazane component, which is
introduced in a liquid or gaseous state of aggregation. The intermediate
formed is in turn preferably further reacted in the second step with the
borane component in excess in an inert solvent, preferably in the gas phase
or more preferably in pure condensed phase. Alternatively, the intermediate
may be caused to react in a liquid state of aggregation with the borane
component which is present in a gaseous state. Depending on p/T
conditions, the target compound is obtained in pure form or mixed with the
secondary product Me3SiCI and the excess borane component and may be
isolated with a phase separator. Using this reaction pathway, it is possible
inter alia to produce the compounds MeCI2SiNHBCI2 (MADB) (1a),
CI3SiNHBCI2 (TADB) (1b), (CH3)2CISiNHBCI2 (DADB), CI3SiNCH3BCI2
(DMTA) or CH3CI2SiNCH3BCI2 (DDMA) in pure form. In the case of MADB,
methyltrichlorosilane, which is introduced in a gaseous state, and
hexamethyldisilazane, which is introduced in a gaseous or liquid state of
aggregation, are caused to react in the gas phase or in a gas phase-liquid
phase reaction. In the case of TADB, tetrachlorosilane is used instead of
methyltrichlorosilane, the reaction being carried out in analogous manner.
The intermediates obtained are respectively MeCI2SiNHSiMe3 and
CI3SiNHSiMe3, which are in each case reacted in the gas phase or preferably
in condensed form with gaseous trichloroborane.

In the formula RxHal3-xSi-NR1-BRyHal2-y (1), the residues R and R1 may in
each case independently mean hydrogen or a hydrocarbon residue with 1 to
20 C atoms, preferably with 1 to 10 C atoms.
A hydrocarbon residue is here a residue which is formed from the elements
carbon and hydrogen. According to the invention, hydrocarbon residues may
be branched or unbranched, saturated or unsaturated. The hydrocarbon
residue may also contain aromatic groups, which may in turn be substituted
with hydrocarbon residues. Examples of preferred hydrocarbon residues are
for example unbranched saturated hydrocarbon residues, such as for
instance C1 to C20 alkyl, in particular methyl, ethyl, n-propyl, n-butyl, n-pentyl,
n-hexyl, n-heptyl, n-octyl, n-nonyl and n-decyl. The residues R and/or R1
may, however, also comprise branched saturated hydrocarbon residues, in
particular branched C3 to C20 alkyls, such as for instance i-propyl, i-butyl, t-
butyl and further branched alkyl residues. In one embodiment, the residues
R and/or R1 comprise one or more olefinically unsaturated groups. Examples
of such residues are vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl,
nonenyl, decenyl, pentadienyl, heptadienyl, octadienyl, nonadienyl and
decadienyl. The residues R and/or R1 may also contain an alkyne group,
thus a C=C bond. In a further embodiment, at least one residue R and/or R1,
preferably all the residues R and/or R1, contain(s) an aromatic group, in
particular an aromatic group with 5 to 10 C atoms, in particular 5 or 6 C
atoms, such as for instance a phenyl group or an aromatic group, in
particular a phenyl group, substituted with a hydrocarbon, in particular a C1
to C10 hydrocarbon, such as for instance methylphenyl, dimethylphenyl,
trimethylphenyl, ethylphenyl or propylphenyl. Including the substituents, the
aromatic residue preferably comprises 5 to 20, in particular to 10 C atoms.
The hydrocarbon residues R and R1 may here in each case mutually
independently be varied.
Preferably, at least one residue R and/or R1 and in particular all the residues
R and/or R1 comprise(s) hydrogen, a C1 to C20 alkyl group, in particular a C1
to C6 alkyl group, a phenyl group, a vinyl group or an allyl group or a
hydrocarbon residue with 1 to 3 C atoms, in particular methyl, ethyl or propyl
and particularly preferably methyl.

The residue Hal denotes a halogen atom and in particular means CI, Br or I,
it being preferred for at least one Hal residue and preferably all Hal residues
to mean CI.
The invention is described in greater detail by the attachec ACCOMPANYING Figures 1-4 and
the following Examples. Figures 1-4 are schematic diagrams of variants of
the production plant for the two-stage method according to the present
invention.

Examples
Example 1: Synthesis of MADB (1a)
Figure 1 shows the method flow chart according to one embodiment of the
invention. The procedures in reaction stages I and II are independent of one
another and are described sequentially.
MeSiCL3 is apportioned from the temperature-controlled holding vessel 1 and
HMDS from the temperature-controlled holding vessel 2 either pure or in an
inert carrier gas stream, for example N2, He, Ar, CO2, into the reactor 3. The
feed materials are both jointly introduced pointwise, or both spatially
distributed or one pointwise and one spatially distributed into the reactor 3 of
the first reaction stage. Thanks to the nature of apportioning and flow control,
a stoichiometric excess of MeSiCI3 to HMDS of at least 2:1 is ensured
throughout the entire reaction chamber.
Reactor temperature is controlled with the assistance of an external heat
exchanger 3a to a temperature between -100°C and 300°C, in particular
between 25°C and 100°C. The total pressure in the reactor 3 is between
0.1 mbar and 2 bar. Pressure and temperature are here adjusted relative to
one another such that the partial pressures of the feed compounds MeSiCI3
and HMDS are below their respective saturation vapour pressures, but the
partial pressure of the intermediate MeCl2SiNHSiMe3 exceeds its saturation
pressure. Under these conditions, the intermediate condenses, is discharged
from the reaction volume via a phase separator 4 and directly supplied to the
second reaction stage, alternatively it may be held in a buffer vessel 5. At the
top of the reactor 3, the feed material MeSiCl3 is condensed from the volatile
components on a heat exchanger 6 and separated by means of a phase
separator 7 from the secondary product Me3SiCI. The temperature of the
heat exchanger 6 is adjusted such that, at the given pressure, MeSiCl3
exceeds its saturation vapour pressure, but Me3SiCI is below its saturation
vapour pressure. MeSiCI3 is recirculated into the reactor. In steady-state
operation, MeSiCI3 and HMDS are replenished from the storage vessels 1_
and 2 in the same molar quantity per unit time as the Me3SiCI is removed
from the reactor.
The intermediate from the first reaction stage is reacted in the second
reaction stage with an excess of BCI3, which is supplied from the

temperature-controlled holding vessel 8. The second reaction stage may be
of an analogous structure to the first stage, the reactor temperature being
adjusted between -100°C and +30°C and the pressure set such that at least
BCI3 is in gaseous form, or may be carried out according to the prior art (DE
4 107 108, DE 10 045 428, DE 10 104 536). The final product is purified by
phase separation.
The phase separators 4 and 7 may function by the principle of mechanical
separation, for example inertial separators or cyclones. Thermal or physico-
chemical separation methods may, however, also be used.
Distillation/rectification or pervaporation may in particular be considered.
The product yield of MADB amounts over both stages to at least 76%
relative to the introduced HMDS. The product is characterised by mass
spectrometry and nuclear magnetic resonance spectroscopy. MS (70 eV):
m/z = 196 (M+-CH3), 174 (M+-HCI), 158 (M+-HCI-CH3), 138 (M+-2HCI), 1H-
NMR: δ= 0.47; 0.49; 13C-NMR: 5= 6.3; 9.3; 128.4; 11B-NMR: 5= 36.4; 41.8.
Example 2: Synthesis of MADB (1a)
The boiling points of the educts, the intermediate, the secondary product and
the final product are in a favourable ratio to one another, such that MADB
may be synthesised by reactive distillation. Figure 2 shows the diagram of
this process variant. The process proceeds in a vacuum column 4. The
educts of the first reaction stage are introduced into the rectification section
together or at different positions 1 and 2. The highly volatile secondary
product MeSiCl3 is enriched towards the top of the column and the
intermediate Cl3SiNHSiMe3 towards the exhausting section of the column.
BCI3 is separately introduced into the column via the inlet 3. The product is
collected at the bottom of the column.
Example 3: Synthesis of TADB (1b)
Preparation of compound (1b) proceeds in analogous manner to the
preparation of compound (1a) in Example 1, but using SiCl4 and HMDS
instead of MeSiCI3 and HMDS as the educts. At the top of the reactor 3,
unreacted SiCI4 and secondary product Me3SiCI leave the reaction chamber
together in gaseous form, as they have the same vaporisation temperature.

The SiCI4/Me3SiCI mixture is accordingly separated by means of a suitable
separation stage 7 (membrane method with porous membranes or
adsorption onto molecular sieves) and the sub-stream enriched with SiCI4 is
condensed in a total condenser 6 and recirculated into the first reaction
stage. In steady-state operation, SiCl4 and HMDS are resupplied to the
process from the storage vessels 1 and 2 in a molar quantity per unit time
which corresponds to the cumulated quantity of Me3SiCI and discharged
SiCl4.
The product yield of TADB amounts over both stages to at least 85% relative
to the introduced HMDS. The product is characterised by mass spectrometry
and nuclear magnetic resonance spectroscopy. MS (70 eV): m/z = 231 (M+),
196 (M+-CI), 160 (M+-CI -HCI); 1H-NMR: δ= 4.41; 11B-NMR: δ= 35.7; 29Si-
NMR: δ=-23.7.
Figure 3 shows the method flow chart according to the described
embodiment of the invention.
Example 4: Synthesis of TADB (1b)
Preparation of compound (1b) proceeds in analogous manner to the
preparation of compound (1a) in Example 2 (Figure 2), but using SiCl4 and
HMDS instead of MeSiCI3 and HMDS as the educts. Moreover, the educts
for the first reaction stage are preferably introduced into the rectification
section at different positions 1 and 2. Due to its higher boiling point, the feed
material HMDS is introduced into the rectification section above the feed
material SiCl4-
Example 5: Synthesis of TADB (1b)
Figure 4 shows the method flow chart according to an embodiment of the
invention. The procedures in reaction stages (I) and (II) are independent of
one another and are described sequentially.
SiCl4, is apportioned from a temperature-controlled holding vessel 1 either
pure or in an inert carrier gas stream, for example N2, He, Ar, CO2l into the

lower part of the reactor of the first reaction stage 2 (for example falling-film
reactor). HMDS is apportioned in liquid form from the storage vessel 3 into
the top of the reactor and reacts countercurrently with gaseous SiCI4. The
molar flow rates of the two reactants are controlled such that a stoichiometric
excess of SiCl4 to HMDS of 1.2 to 1.5 is maintained in the reaction chamber.
Reactor temperature is controlled between -50°C and 200°C with the
assistance of a external heat exchanger 2a. The total pressure in the reactor
2 is between 1 mbar and 1 bar. Pressure and temperature are here adjusted
relative to one another such that the partial pressures of the feed compound
SiCI4 and of the secondary product MeSiCI3 are below their respective
saturation vapour pressures, but HMDS and the intermediate CI3SiNHSiMe3
are in liquid form. This is the case, for example, with the combination 60°C /
300 mbar. The intermediate is discharged in liquid form at the bottom of the
falling-film reactor and directly supplied to the second reaction stage.
Alternatively, the intermediate may be held in a buffer vessel 5. At the top of
the reactor 2, unreacted SiCl4, and secondary product Me3SiCI leave the
reaction chamber together in gaseous form, as they have virtually the same
vaporisation temperature. The further treatment thereof proceeds as
described in Example 3.
The intermediate from the first reaction stage is reacted in the second
reaction stage with an excess (1.1-1.5 times) of BCI3, which is supplied from
the temperature-controlled holding vessel 8. The second reaction stage may
be of an analogous structure to the first, but may also take the form of a
plate column, temperature and pressure conditions being adjusted relative to
one another such that feed material BCI3 is in gaseous form and the
secondary product Me3SiCI is in gaseous or liquid form, while the
intermediate stage CI3SiNHSiMe3 and the final product CI3SiNHBCI2 (TADB)
are in liquid form. Excess BCI3 and the secondary product Me3SiCI are
discharged in gaseous form from the top of the reactor and separated with a
phase separator. Recovered BCI3 is supplied, for example, to the holding
vessel 8, while Me3SiCI is recirculated into the production of the feed material
HMDS. The final product is purified by phase separation and optionally
separated from the secondary product Me3SiCI.

The phase separators 4 and 9 may function by the principle of mechanical
separation, for example inertial separators or cyclones. Thermal or physico-
chemical separation methods may, however, also be used.
Distillation/rectification or pervaporation may in particular be considered.
The product yield of TADB amounts over both stages to at least 84% relative
to the introduced HMDS. The product is characterised by mass spectrometry
and nuclear magnetic resonance spectroscopy (see Example 3).

1. A sifazane cleavage method comprising reacting a silazane compound with
a cleaving reagent, wherein at least one of the silazane compound and the
cleaving reagent is introduced in gaseous form and wherein said method is
carried out continuously.
2. A method as claimed in claim 1,
wherein one educt in the liquid phase is reacted with a second educt in the
gaseous phase.
3. A method as claimed in claim 1,
wherein all the educts are introduced in gaseous form.
4. A method as claimed in any one of the preceding claims,
wherein a silazane compound is reacted with at least one compound of the
formula (2) selected from
BHal3-xRx, AlHal3-xRx, GaHal3-xRx, InHal3-xRx, SiHal4-yRy, GeHal4-yRy, PHal3-xRx,
PHal5-zRz, TiHal4-yRy, ZrHal4-yRy, VHal3-xRx, VHal4-yRy, NbHal5-zRz, TaHal5-zRz,
CrHal3-xRx, MoHal4-yRy, MoHal5-zRz, WHal6-zRz, FeHal3-xRx or ZnCl2
in which x = 0 or 1, y = 0, 1 or 2 and z = 0,1, 2 or 3, Hal is selected from F,
CI, Br and I, and R represents hydrogen or a hydrocarbon residue with 1 to
20 C atoms.
5. A method as claimed in any one of the preceding claims,
wherein the target product of the reaction is removed from the reaction
mixture.
6. A method as claimed in any one of the preceding claims,
wherein one of the educts is introduced in excess.

7. A continuous method comprising silazane cleavage as claimed in one of
claims 1 to 6 for the production of a compound which comprises the
structural feature N-Y, in which Y is in each case independently selected
from B, Al, Ga, In, Si, Ge, P, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Fe or Zn, wherein a
silazane compound is reacted with a compound of the formula (2) selected
from
BHal3-xRx, AlHal3-xRx, GaHal3-xRx, InHal3-xRx, SiHal4-yRy, GeHal4-yRy, PHals-xRx,
PHal5-zRz, TiHal4-yRy, ZrHal4-yRy, VHal3-xRx, VHal4-yRy, NbHal5-zRz, TaHal5-zRz,
CrHal3-xRx, MoHal4-yRy, MoHal5-zRz, WHal5-zRz, FeHal3-xRx or ZnCI2
in which x = 0 or 1, y = 0, 1 or 2 and z = 0, 1, 2 or 3, Hal is selected from F,
CI, Br and I, and R represents hydrogen or a hydrocarbon residue with 1 to
20 C atoms.
8. A continuous method comprising two silazane cleavage reactions as
claimed in any one of claims 1 to 6 for the production of a compound which
comprises the structural feature X-N-Y, in which X and Y are in each case
independently selected from B, Al, Ga, In, Si, Ge, P, Ti, Zr, V, Nb, Ta Cr, Mo,
W, Fe or Zn,
comprising the steps
reacting a compound of the formula (3)
R23SiNR1Si R33,
in which R2 and R3 in each case mutually independently represent a
hydrocarbon residue with 1-20 carbon atoms and R1 represents hydrogen
or a hydrocarbon residue with 1-20 C atoms, in succession in any desired
order with a compound of the formula (2) selected from
BHal3-xRx, AlHal3-xRx, GaHal3-xRx, InHal3-xRx, SiHal4-yRy, GeHal4-yRy, PHal3-xRx
PHal5-zRz, TiHal4-yRy, ZrHal4-yRy, VHal3-xRx, VHal4-yRy, NbHal5-zRz, TaHal5-zRz,
CrHal3-xRx, MoHal4-yRy, MoHal5-zRz, WHal6-zRz, FeHl3-xRx or ZnCI2
in which x = 0 or 1, y = 0, 1 or 2 and z = 0, 1, 2 or 3, Hal is selected from F,
CI, Br and I, and R represents hydrogen or a hydrocarbon residue with 1 to
20 C atoms,
and a compound of the formula (4) selected from
BHal3-xRx, AlHal3-xRx, GaHal3-xRx, InHal3-xRx, SiHal4-yRy, GeHal4-yRy, PHal3-yRx,
PHals5-zRz, TiHal4-yRy, ZrHal4-yRy, VHal3-xRx, VHal4-yRy, NbHal5-zRz, TaHal5-zRz,
CrHal3-xRx, MoHal4-yRy, MoHal5-zRz, WHal6-zRz, FeHal3-xRx or ZnCI2
in which x = 0 or 1, y = 0, 1 or 2, z = 0, 1, 2 or 3, Hal is selected from F, CI,
Br and I, and R represents hydrogen or a hydrocarbon residue with 1-20 C
atoms.

9. A method as claimed in any one of the preceding claims,
wherein the product formed is a molecular single component precursor for
non-oxide ceramics.
10. A method as claimed in any one of the preceding claims,
wherein a compound of the formula (1)
Rx Hal3-xSi-NR1-BRyHal2-y is produced, wherein SiHal4-yRy is used as the
compound of the formula (2) and BHal3-xRx is used as the compound of the
formula (4).
11. A method as claimed in any one of the preceding claims,
wherein the reaction is carried out at temperatures of-100°C to 300°C
and/or a pressure of 0.1 mbar to 2 bar.
12. A method as claimed in any one of the preceding claims,
wherein pressure and temperature are adjusted such that the educts are in
gaseous form, but the intermediate and final product are in liquid form.
13. A method as claimed in any one of the preceding claims,
wherein the reaction with compounds of the formula (2) is carried out at a
temperature of ≥ 25°C, in particular ≥ 50°C.
14. A method as claimed in any one of the preceding claims,
wherein the silazane compound is reacted with an excess of compounds of
the formula (2).
15. A method as claimed in any one of the preceding claims,
wherein R3SiHal is separated as secondary product from the method.
16. A method as claimed in any one of the preceding claims,

wherein pressure and temperature are adjusted such that the partial
pressure of a secondary product of the formula (5) formed during the
reaction
R3SiHal
is lower than the saturation vapour pressure thereof,
in which Hal in each case independently means CI, Br or I, R in each case
independently represents a hydrocarbon residue with 1 to 20 C atoms or
hydrogen,
x = 0, 1 or 2 and y = 0 or 1.
17. A method as claimed in any one of the preceding claims,
wherein compound of the formula (3) is reacted first with a compound of the
formula (2) and thereafter in a further stage with a compound of the formula
(4).
18. A method as claimed in claim 8,
wherein the reaction of the compound of the formula (3) with the compound
of the formula (2) is carried out under pressure and temperature conditions,
under which the educts are in gaseous form and the intermediate
condenses as a liquid, the intermediate being separated in liquid form.
19. A method as claimed in claim 18,
wherein the reaction of the compound of the formula (3) with the compound
of the formula (2) is carried out under pressure and temperature conditions,
under which the educt of the formula (3) is in gaseous form, while the educt
of the formula (2) and the intermediate are in liquid form.
20. A method as claimed in any one of the preceding claims,
wherein the compound CH3CI2SiNHBCI2 (MADB), CI3SiNHBCI2 (TADB),
(CH3)2CISiNHBCI2 (DADB), CI3SiNCH3BCI2 (DMTA) or CH3CI2SiNCH3BCI2
(DDMA) is produced.

ABSTRACT
Title: Continuous silazane cleavage method.
A silazane cleavage method comprising reacting a silazane compound with a
cleaving reagent, wherein at least one of the silazane compound and the
cleaving reagent is introduced in gaseous form and wherein said method is
carried out continuously.

Documents:

01942-kolnp-2007-abstract.pdf

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01942-kolnp-2007-correspondence others 1.1.pdf

01942-kolnp-2007-correspondence others 1.2.pdf

01942-kolnp-2007-correspondence others 1.3.pdf

01942-kolnp-2007-correspondence others.pdf

01942-kolnp-2007-description complete.pdf

01942-kolnp-2007-drawings.pdf

01942-kolnp-2007-form 1.pdf

01942-kolnp-2007-form 2.pdf

01942-kolnp-2007-form 3.pdf

01942-kolnp-2007-form 5.pdf

01942-kolnp-2007-gpa.pdf

01942-kolnp-2007-international exm report.pdf

01942-kolnp-2007-international publication.pdf

01942-kolnp-2007-international search report.pdf

01942-kolnp-2007-others.pdf

01942-kolnp-2007-pct request form.pdf

01942-kolnp-2007-priority document.pdf

1942-KOLNP-2007-(08-11-2011)-ABSTRACT.pdf

1942-KOLNP-2007-(08-11-2011)-AMANDED CLAIMS.pdf

1942-KOLNP-2007-(08-11-2011)-DESCRIPTION (COMPLETE).pdf

1942-KOLNP-2007-(08-11-2011)-DRAWINGS.pdf

1942-KOLNP-2007-(08-11-2011)-EXAMINATION REPORT REPLY RECIEVED.pdf

1942-KOLNP-2007-(08-11-2011)-FORM 1.pdf

1942-KOLNP-2007-(08-11-2011)-FORM 2.pdf

1942-KOLNP-2007-(08-11-2011)-FORM 3.pdf

1942-KOLNP-2007-(08-11-2011)-FORM 5.pdf

1942-KOLNP-2007-(08-11-2011)-OTHERS.pdf

1942-KOLNP-2007-CORRESPONDENCE.pdf

1942-KOLNP-2007-EXAMINATION REPORT.pdf

1942-KOLNP-2007-FORM 18 1.1.pdf

1942-kolnp-2007-form 18.pdf

1942-KOLNP-2007-FORM 26.pdf

1942-KOLNP-2007-FORM 3.pdf

1942-KOLNP-2007-FORM 5.pdf

1942-KOLNP-2007-GRANTED-ABSTRACT.pdf

1942-KOLNP-2007-GRANTED-CLAIMS.pdf

1942-KOLNP-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

1942-KOLNP-2007-GRANTED-DRAWINGS.pdf

1942-KOLNP-2007-GRANTED-FORM 1.pdf

1942-KOLNP-2007-GRANTED-FORM 2.pdf

1942-KOLNP-2007-GRANTED-SPECIFICATION.pdf

1942-KOLNP-2007-OTHERS.pdf

1942-KOLNP-2007-PRIORITY DOCUMENT.pdf

1942-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf

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Patent Number

252875

Indian Patent Application Number

1942/KOLNP/2007

PG Journal Number

23/2012

Publication Date

08-Jun-2012

Grant Date

06-Jun-2012

Date of Filing

30-May-2007

Name of Patentee

MAX-PLANCK-GESELLSCHAFT ZUR FORDERUNG DER WISSENSCHAFTEN E.V.

Applicant Address

HOFGARTENSTRASSE 8, 80539 MUNCHEN

Inventors:

#	Inventor's Name	Inventor's Address
1	JANSEN, MARTIN	BERGHALDE 18/1, 71229 LEONBERG
2	JASCHKE, BRITTA	FURTWANGLERSTR. 97, 70195 STUTTGART
3	KOLIOS, GRIGORIOS	AUGUSTENSTRASSE 122, 70197 STUTTGART

PCT International Classification Number

C07F 7/10,C01B 35/00

PCT International Application Number

PCT/EP2005/013384

PCT International Filing date

2005-12-13

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10 2004 059 942.4	2004-12-13	Germany