Title of Invention

PROCESS FOR THE MANUFACTURE OF DIESTERS

Abstract Abstract PROCESS FOR THE MANUFACTURE OF DIESTERS The present invention relates to a process for the preparation of diesters from imide or dinitrile compounds. More particularly, said invention relates to a process for the preparation of diester compounds from dinitrile compounds by utilizing vapor phase hydrolysis of dinitrile compounds in the presence of alcohol for obtaining diester compounds. Still more particularly, said invention relates to a process for the preparation of diesters from branched dinitrile compounds such as methylglutaronitrile or the branched dinitrile compounds obtained as secondary products during the preparation of adiponitrile by hydrocyanation of bucadiene.
Full Text

Process for the manufacture of diesters
The present invention relates to a process for the manufacture of diesters from imide or dinitrile compounds.
It relates more particularly to a process for the manufacture of diester compounds from dinitrile compounds employing a vapour-phase hydrolysis of dinitrile compounds in the presence of alcohol to produce diester compounds.
It relates even more particularly to a process for the manufacture of diesters from branched dinitrile compounds, such as methylglutaronitrile or branched dinitrile compounds obtained as by¬products in the process for the manufacture of adiponitrile by hydrocyanation of butadiene.

Process for the manufacture of diesters
The present invention relates to a process for the manufacture of diesters from imide or dinitrile compounds.
it relates more particularly to a process for the manufacture of diester compounds from dinitrile compounds employing a vapour-phase hydrolysis of dinitrile compounds.
It relates even more particularly to a process for the manufacture of diesters from branched dinitrile compounds, such as methylglutaronitrile or branched dinitrile compounds obtained as by¬products in the process for the manufacture of adiponitrile by hydrocyanation of butadiene.
Oxygenated solvents based on diesters are increasingly used as a replacement for other hydrocarbon, chlorinated or oxygenated solvents more aggressive to the environment.
This is because diester solvents, such as those sold under the known name of Rhodia Solv RDPE, obtained from a mixture of adipic acid, glutaric acid and succinic acid, exhibit the advantage of having a very favourable toxicological profile and are biodegradable and readily recyclable. Diester compounds obtained from branched compounds and more particularly from a mixture of methylglutaronitrile, ethylsuccinonitrite and adiponitrile have also been proposed in unpublished French patent application No. 0602011.
In this patent, a manufacturing process was described which consists in reacting the dinitrile compounds with an alcohol in the presence of an inorganic acid, followed by hydrolysis. This process is known by the name of the Pinner reaction.
However, an ammonium salt is obtained as by-product in this process.
One of the aims of the present invention is to provide a process for the manufacture of diesters from dinitrile compounds which does not exhibit the disadvantages of the processes of the prior art and which in particular does not generate significant amounts of effluents or by-products possibly harmful to the environment.
To this end, a subject-matter of the invention is a process for the manufacture of diester compounds by reaction between an imide compound of following general formula (1):


In this second embodiment, it is advantageous for the amounts of water and alcohol used to make it possible to have a molar ratio R of the number of molecules of alcohol to the number of

molecules of water greater by at least 10% than a stoichiometric ratio Rstoicn of the stoichiometric number of molecules of alcohol for converting the imide fomied from the dlnitrile to diesters to the stoichiometric number of molecules of water necessary to hydrolyse the dinitrile compound to imide compound.
The stoichiometric number of molecules of water for carrying out the cyclizing hydrolysis of a
dinitrile compound is equal to 2.
The stoichiometric number of molecules of alcohol necessary for obtaining the diester is also
equal to 2.
Thus, the ratio Rstoicn is equal to 1.
The ratio R is greater than 1.1 and advantageously less than 20 and preferably less than or equal
to 10.
The cyclizing hydrolysis reaction is advantageously carried out at a temperature of less than SOO'C, preferably of between 250X and 450'C.
Furthermore, the molar ratio of the water to the nitrite compound is between 1 and 10 and preferably between 2 and 5.
The cyclizing hydrolysis reaction carried out in the absence of alcohol (first embodiment) or in the presence of alcohol (second embodiment) is implemented continuously or batchwise in types of reactors which make it possible to use a solid catalyst, either in the fomn of a fixed bed or in the form of a fluldized bed. The reaction can be carried out at atmospheric presRure or under pressure, for example under a pressure which can range up to 10 bar.
The diester compounds, after condensation, are extracted from the reaction medium by the standanj techniques for separating and purifying organic compounds, such as distillation or liquid/liquid extraction, for example.
Likewise, in the first embodiment of the invention, the imide compound obtained by hydrolysis of the dinitrile compound can advantageously be separated from the reaction medium and purified by the standard techniques. However, It is also possible to use the reaction medium obtained after the hydrolysis stage, without separation or purification, directly as reactant in the stage of reaction with an alcohol.

' The solid catalyst used by the cyciizing hydrolysis reaction is chosen from the group consisting of metai oxides, such as alumina or titanium oxide, heteropolyacids, zeolites of pentasii and faujasite type, clays, metal phosphates, silica/alumina mixtures and the like.
Thus, the clays suitable for the invention are in particular phyllosilicates, which are categorized by groups according to their nature and their physicochemical properties, among which groups may be mentioned kaolins, serpentines, smectites or montmorillonites, illites or micas, glauconites, chlorites or vermicuiites, attapulgites or sepiolites, mixed-layer clays, allophanes or imogolites and high-alumina clays.
Some clays possess a lamellar structure with an expandable network. They exhibit the distinctive feature of adsorbing various solvents, in particular water, between the sheets of which they are composed, which brings about swelling of the solid as a result of the weakening of the electrostatic bonds between the sheets. These clays belong essentially to the smectites group (or also montmorillonite group) and, for some of them, to the vermicuiites group.
Their structure is composed of "basic" sheets comprising three layers; two simple layers of SiO* tetrahedra in \Nh\ch a portion of the silicon can be replaced by other cations in the tetrahedral
position, such as Al^"*" or optionally Fe^*, and, between these two layers of tetrahedra, a layer of
oxygen octahedra, at the centre of which are situated metal cations, such as Al^"*", Fe*^"*" or Mg2+. This octahedral layer is composed of a compact stack of oxygens originating either from the vertices of the preceding tetrahedra or from hydroxy! groups OH. The compact hexagonal network of these oxygens comprises 6 octahedral cavities.
When the metal cations occupy 4 of these cavities (2 cavities out of 3, as in the case of aluminium, for example), the layer is said to be dioctahedrat; when they occupy all the cavities (3 cavities out of 3, as in the case of magnesium, for example), the layer is said to be trioctahedral.
The basic sheets of these clays carry negative charges which are compensated for by the presence of exchangeable cations; alkali metal cations, such as Li"*", Na"*" or K+, alkaline earth metal cations, such as Mg2+ or Ca2+, and optionally the hydronium ion HaO*. The smectites have charge densities on the sheets which are lower than those of the clays of the vermiculite type; approximately 0.66 charge per unit cell, against 1 to 1.4 charges per unit cell for the vermicuiites.
The compensating cations are essentially sodium and calcium in the smectites and magnesium and calcium in the vermicuiites. From the viewpoint of the charge densities, smectites and

' vermiculites are intermediates between talc and pyrophyllite, on the one hand, the sheets of which are neutral, and micas, on the other hand, characterized by a high charge density on the sheets
(approximately 2 per unit cell) generally compensated for by K"*" ions. The interlayer cations of the smectites and vermiculites can be fairly easily replaced by ion exchange by other cations, such as, for example, ammonium ions or alkaline earth metal ions or rare earth metal ions.


These solids are thus potentially advantageous in catalysis as their potential specific surface and
their potential acidity are high.
According to a preferred form of the invention, the clay constituting the cyclisation catalyst of
esters or amides of 6-aminocaprQ*ic acid to a lactame is a smectite. More preferably, the clay is
montmorillonite.
Some clays unfortunately have the disadvantage of losing their expanded nature on heating to
100°C and, for this reason, of not retaining the increase in specific surface resulting from their
expansion. This Is the case in particular with smectites.
Various methods have been described in the prior art for introducing, between the sheets of
smectites, pillars or bridges in order to obtain bridged smectites which retain a high interlayer
spacing after having been subjected to a heat treatment.
One method, which consists in introducing bridges composed of oligomers of a hydroxide of a
metal, in particular of aluminium hydroxide, has been described by Lahav, Shami and Shabtai in
Clays and Clay Minerals, vol. 26 (No. 2), pp. 107-115 (1978), and in French Patent 2 394 324. The
formation of bridges composed of oligomers of mixed hydroxides of silicon and of boron is
described in Patent US 4 248 739. A technique for bridging smectites by dialysis using hydroxides
of aluminium, of chromium, of zirconium and titanium, and the like, is claimed in Patent
EP 0 073 718.
The principle of these methods consists in bringing the clay into contact with a solution comprising
more or less oligomerized ionic entities of the hydroxy-aluminium type (in the case of aluminium).
This operation is generally carried out in a solution of relatively low concentration, at a
temperature of less than SC'C and if possible in the absence of cloudiness formed by the
beginning of precipitaiion of the metal hydroxide. The concentrations of the metal ion and of the
clay have to be optimized in order for there to be sufficient formation of solid pillars and for the
porosity of the clay not to be greatly reduced by the insertion of an excessively large amount of
metal oxide.
When the interiayer alkali metal or alkaline earth metal ions are replaced by protons, either directly, using a very dilute solution, or, preferably, by exchange with an ammonium salt, followed by calcination between 300 and 700°C, the bridged smectites acquire a high acidity, although lower overall than those of conventional zeolites of Y or mordenite type, for example.
According to a specific alternative fomn of the invention, the catalyst can comprise, in addition to a clay, one or more other metal compounds, often referred to as doping agents, such as, for example, chromium, titanium, molybdenum, tungsten, iron or zinc compounds. Among these doping agents, chromium and/or iron and/or titanium compounds are regarded as the most

advantageous. These doping agents usually represent, by weight per weight of clay, from 0% to 10% and preferably from 0% to 5%.
The term "metal compound" is understood to mean both the metal element and the metal ion or any combination comprising the metal element.
Another category of preferred catalyst of the invention consists of a particulate catalyst obtained by shaping at feast one simple or mixed inorganic oxide of at least one element chosen from the group consisting of silicon, aluminium, titanium, zirconium, vanadium, niobium, tantalum, tungsten, molybdenum, iron or rare earth metals. These oxides can exist in an amorphous or crystalline fomn.
According to the invention, the particulate catalyst comprises at least one macroporosity characterized by a pore volume, corresponding to the pores with a diameter of greater than 500 A, of greater than or equal to 5 ml/100 g.
This macroporosity is advantageously fomned during the process of shaping the particles by techniques described below or such as, for example, the addition of a pore-forming agent. The catalyst can be employed in various forms, such as beads, crushed materials, extrudates in the form of hollow or solid cylindrical granules, a honeycomb or pellets, it being possible for the shaping optionally to be can'ied out using a binder.
The catalyst may first of all be in the form of beads of inorganic oxides resulting from an oil drop shaping operation (or drop coagulation). Beads of this type can, for example, be prepared by a similar process as that described for the formation of alumina beads in Patents EP-A-0 015 801 or tP-A-u 097 559. The porosity can be controlled in particular, accorciinn to the process described in Patent EP-A-0 097 539, by coagulation as drops of an aqueous suspension or dispersion of inorganic oxide.
The beads can also be obtained by the process of agglomeration in a granulator or rotating drum. The catalysts may also be in the form of extrudates of inorganic oxides. The latter can be obtained by kneading and then extruding a material based on the inorganic oxide. The porosity of these extmdates can be controlled by the choice of the oxide employed and by the conditions for preparing this oxide or by the conditions for kneading this oxide before extrusion. The inorganic oxide can thus be mixed, during the kneading, with pore-forming agents. By way of example, the extrudates can be prepared by the process described in Patent US 3 856 708.
Similarly, beads of controlled porosity can be obtained by addition of pore-forming agent and agglomeration in a rotating pan or granulator or by the oil drop process.
According to another characteristic of the invention, the catalyst particles exhibit a specific surface of greater than lOmVg and a pore volume of equal to or greater than 10 ml/100 g, the pore

volume corresponding to the pores with a diameter of greater than 500 A being greater than or
equal to 10 ml/100 g.
According to another characteristic of the invention, the catalyst particles exhibit a specific surface
of greater than 50 m*/g.
Advantageously, they exhibit a total pore volume of greater than or equal to 15 m(/100g with a
pore volume, corresponding to the pores with a diameter of greater than 200 A, of greater than or
equal to 15 ml/100 g, preferably of greater than or equal to 20 miyiOOg.
These particulate catalysts can also comprise at least one element chosen from the list consisting
of silicon, titanium, zirconium, vanadium, niobium, tantalum, tungsten, molybdenum, iron and rare
earth metals or can be obtained by deposition and/or adsorption on the support of at least one
oxygen compound of at least one element chosen from the group consisting of the elements
belonging to Groups 1 to 16 of the Periodic Table of the Elements (new Table), this list also
including the rare earth metals. These elements or compounds are deposited or adsorbed on the
particulate catalyst.
In the procedure comprising a porous particulate catalyst supporting oxygen compounds of
elements, these elements are advantageously chosen from the list consisting of silicon, titanium,
zirconium, vanadium, niobium, tantalum, tungsten, molybdenum, phosphorus, boron, iron, alkali
metals, alkaline earth metals and rare earth metals. The oxygen compound is advantageously a
simple or mixed oxide of one or more of the elements mentioned above.
In this embodiment, the porous catalyst is preferably an aluminium oxide. Advantageously, this
alumina exhibits the specific surface and pore distribution characteristics defined above.
The concentration by weight of oxygen compound supported en a porous support Is advantageously between 1000 ppm and 30%, expressed as weight of element of the oxygen compound with respect to the total weight of the catalyst. This concentration is more preferably between 0.5% and 15% by weight.
When the porous supports correspond to aluminas in accordance with the invention, the latter are generally obtained by dehydration of gibbsite, bayerite, nordstrandite or their various mixtures. The various processes for the preparation of the aluminas are described in the Kirk-Othmer encyclopaedia, volume 2, pages 291-297.
The aluminas employed in the present process can be prepared by bringing a hydrated alumina, in the finely divided form, into contact with a stream of hot gas at a temperature of between 400°C and 1000°C, and then maintaining contact between the hydrate and the gases for a period of time ranging from a fraction of a second up to 10 seconds, and finally separating the partially dehydrated alumina and the hot gases. Reference may in particular be made to the process described in United States Patent US 2 915 365.

It is also possible to autoclave agglomerates of aluminas obtained above, in aqueous medium,
optionally in the presence of acid, at a temperature of greater than lOOX and preferably of
between 150°C and 250*C, for a period of time preferably of between 1 and 20 hours, and then to
dry and calcine them.
The calcination temperature is adjusted so that specific surfaces and pore volumes lying within the
regions of values indicated above are obtained.
The catalysts of the invention advantageously have a specific surface of greater than 50 mVg,
In addition, they advantageously exhibit pores with a diameter of greater than 0.1 pm, the pore
volume contributed by these pores being greater than or equal to 5 ml/100 g, advantageously
greater than or equal to 10 ml/100 g.
In a preferred embodiment of the invention, these catalysts also comprise pores with a diameter of
equal to or greater than 0.5 ^m, the corresponding pore volume being equal to or greater than
5 ml/100 g, preferably greater than or equal to 10 ml/100 g.
This pore volume generated by the pores with a diameter of greater than 500 A, preferably of
greater than 0.1 ^m and advantageously of greater than 0.5 ^m makes it possible to obtain
catalysts with a high cycle time as catalysts for the reaction for the cyclization of esters or amides
of 6-aminocaproic acid to give lactams. Thus, such catalysts can be used in industrial processes
for the production of lactams.
According to the invention, the catalysts comprising oxygen compounds supported by a porous catalyst are obtained generally by impregnation of the catalyst, in particular of alumina, by a solution of a salt or compounds of the elements mentioned above and are then dried and calcined at a temperature equal to or greater than 4uO=C in ordef io convert, optionally snd sdvantagecusly, the said compounds or salts to oxygen compounds, preferably to oxides. The oxides are deposited at the surface of the pores of the porous catalyst. In another embodiment, the compounds of elements can be added to the material constituting the porous catalyst before it is shaped or during the shaping process.
The impregnated catalysts are preferably calcined under an oxidizing atmosphere, such as air.
According to yet another embodiment of the invention, the catalyst can be a metal phosphate of
general formula:
(P04)nHhM, {lmp)p in which:

' - M represents a divalent, trivalent, tetravalent or pentavalent element chosen from Groups 2a, 3b, 4b, 5b, 6b, 7b, 8, 2b, 3a, 4a and 5a of the Periodic Table of the Elements or a mixture of several of these elements or M=0,
- Imp represents a basic impregnation compound composed of an alkali metal or alkaline earth metal or of mixtures of several of these metals, in combination with a counteranion in order to provide electrical neutrality,
- n represents 1, 2 or 3,
- h represents 0, 1 or 2,
- p represents a number between 0 and 1/3 and corresponds to a molar ratio of the impregnating material Imp to the impregnated material (P04)nHhM.
Mention may in particular be made, among the metals of Groups 2a, 3b, 4b, 5b, 6b, 7b, 8, 2b, 3a, 4a and 5a of the Periodic Table of the Elements, of beryllium, magnesium, calcium, strontium, barium, aluminium, boron, gallium, indium, yttrium, the lanthanides, such as lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and tutetium, zirconium, titanium, vanadium, niobium, iron, germanium, tin or bismuth.
Among the phosphates of lanthanides, it is possible to distinguish a first family which brings together orthophosphates of light rare earth metals, also known as eerie rare earth metals, including lanthanum, cerium, praseodymium, neodymium, samarium and europium. These orthophosphates are dimorphic. They exhibit a hexagonal structure and change towards a monoclinic structure when they are heated at a temperature of 600 to 800°C.
A second family of phosphates of ianihanides brinys together the orthophosphates of gadniinium, of terbium and of dysprosium. These orthophosphates exhibit the same structure as the orthophosphates of eerie rare earth metals but additionally exhibit a third crystalline phase of quadratic structure at high temperature (approximately 1700'*C).
A third family of phosphates of lanthanides brings together the orthophosphates of heavy rare earth metals, also known as yttric rare earth metals, including yttrium, holmium, erbium, thulium, ytterbium and lutetium. These compounds crystallize solely in the quadratic form.
Recourse is preferably had, among the various abovementioned families of orthophosphates of rare earth metals, to the orthophosphates of eerie rare earth metals.
Use may be made of metal phosphates of the above formula which are mixtures of phosphates of several of the metals indicated above or mixed phosphates of several of the metals indicated above or also mixed phosphates comprising one or more of the metals indicated above and one or more other metals, such as alkali metals or alkaline earth metals.

The counteranions participating in the formula of the impregnation compound Imp are basic. Use may in particular be made of the hydroxide, phosphate, hydrogenphosphate, dihydrogenphosphate, chloride, fluoride, nitrate, benzoate or oxalate tons, without this list being limiting.
The molar ratio p is preferably between 0.02 and 0.2.
If reference is made to the general techniques for the preparation of phosphates (such as described in particular in Pascal P. "Nouveau traite de chimie minerale" [New Treatise on Inorganic Chemistry], volume X (1956), pages 821-823, and in Gmelins "Handbuch der anorganischen Chemie" [Handbook of Inorganic Chemistry] (8th edition), volume 16 (C), pages 202-206 (1965)), it is possible to distinguish two main routes of access to phosphates. On the one hand, the precipitation of a soluble salt of the metal (chloride, nitrate) by ammonium hydrogenphosphate or phosphoric acid. On the other hand, the dissolution of the oxide or of the carbonate of the metal (which are insoluble) with phosphoric acid, generally under warnn conditions, followed by precipitation.
The precipitated phosphates obtained according to one of the routes indicated can be dried, treated with an organic base (such as ammonia) or an inorganic base (such as an alkali metal hydroxide) and be subjected to a calcination, it being possible for these three operations to be carried out in the order shown or in a different order.
The metal phosphates of the above formula for which the symbol p is greater than 0 can be prepared by impregnation of the compound (P04)nHnM, prepared according to one of the
techniques described above with a solution or a suspension of Imp in a volatile solvent, such as water, preferably.
The results improve as Imp increases in solubility and the more recently the compound (P04)nHhM has been manufactured.
Thus, an advantageous process for the preparation of these phosphates consists;
a) in synthesizing the compound (P04)nHhM and then, preferably without separating
(P04)nHhM from the reaction medium,
b) in introducing the impregnating material imp into the reaction medium;
c) in separating the possible residual liquid fnsm the reaction solid;
d) in drying and optionally calcining.
The performances of these catalysts and in particular their resistance to deactivation can be further improved by calcination. The calcination temperature will advantageously be between 300X and lOOOX and preferably between 400'C and 900"C. The duration of the calcination may vary within wide limits. By way of indication, it generally lies between 1 hour and 24 hours.

Mention may more particularly be made, among the catalysts preferred in the process of the invention, of lanthanum phosphate, calcined lanthanum phosphate, lanthanum phosphate in combination with a caesium, rubidium or potassium derivative, calcined cerium phosphate, cerium phosphate in combination with a caesium, rubidium or potassium compound, samarium phosphate in combination with a caesium, rubidium or potassium compound, aluminium phosphate, aluminium phosphate in combination with a caesium, rubidium or potassium compound, calcined niobium phosphate, niobium phosphate in combination with a caesium, rubidium or potassium compound, calcined zirconium hydrogenphosphate or zirconium hydrogenphosphate in combination with a caesium, rubidium or potassium compound.
The orthophosphates described above can be used as a mixture with phosphoric acid (H3PO4).
Use may also be made, as catalyst, of pyrophosphates of rare earth metals, in particular of lanthanum, alone or as a mixture with the orthophosphates described above. Such catalysts are described in European Patent EP1066255.
The preferred dinitrile compounds of the invention are compounds obtained by hydrocyanation of butadiene and more particularly still the branched dinitrile compounds produced by the double hydrocyanation of butadiene, such as methylgiutaronitrile or ethylsuccinonitrile. Advantageously, the process of the invention uses a mixture of dinitrile compounds comprising methylgiutaronitrile, ethylsuccinonitrile and adiponitrile.
This mixture is obtained in particular by separation, for example by riistillation^ from the reaction medium obtained after hydrocyanation of the pentenenitriles, in the process for the production of adiponitrile by double hydrocyanation of butadiene.
The alcohols suitable for the invention are, for example, branched or unbranched and cyclic or acyclic aliphatic alcohols which can comprise an aromatic nucleus and which can comprise from 1 to 20 carbon atoms. Mention may be made, as preferred examples, of the following alcohols: methanol, propanol, isopropanol, benzyl alcohol, ethanol, n-butanoi, isobutanol, pentanols, cyclohexanol, hexanol, isooctanol or2-ethylhexanol.
The composition or the diesters obtained by the process of the invention can be used alone or as a mixture with other solvents or with water in the solution or emulsion form. In particular, they can be used as a mixture with the diesters of the linear diacids cited above (RPDE).

These diester compounds have applications as solvent in numerous fields, such as paints, varnishes and lacquers, the industry for coating surfaces or any other article, such as cables, for example, the ink industry, lubricants for textiles, binders and resins for foundry cores and moulds, cleaning products, cosmetic formulations, for the implementation of certain chemical reactions, in soil and plant treatment compositions and more generally the use, alone or in a formulation, as cleaning, pickling or degreasing solvent in any industrial or domestic activity. These diester compounds can also be used as plasticizers for some plastics or as monomers for the manufacture of polymers.
Other advantages or characteristics of the invention will be described in more detail and will be better illustrated in the light of the examples given below purely by way of illustration.
Synthesis of the diesters in one stage
A medium comprising water, methanol and a mixture of dinitrile compounds with the following composition by weight:
> 86% by weight of methylglutaronitriie
> 11 % by weight of ethylsuccinonitrile
> 3% by weight of adiponitrile
is introduced using a syringe driver, at a flow rate of 1 ml/h, into a Pyrex tube placed vertically in an oven, the temperature of which is SOCC, and swept by a 1 l/h nitrogen stream. 4 ml of catalyst are placed between 2 layers of glass powder with a volume of 5 ml. Injection is carried out immediately above the upper layer of glass and the nitrogen stream carries the products through the catalyst bed. At the outlet ot the oven, the gases are cundensed in a tube placed ;r^ an ice bat! and are then analysed by gas chromatography. The medium introduced has the following molar composition:
-1 mol of dinitrile compounds
-2 mol of water
-8 mol of methanol
A test was earned out using, as catalyst, macroporous alumina sold by Procatalyse under the name SCM 139 XL The degree of conversion of the dinitrile compounds is 25%. The yield of diesters is 0.3%. If was found that the reaction medium comprises cyanoesters, corresponding to an intermediate product capable of being converted to diesters. The yield of cyanoesters is 2.4%.
A second test was carried out using, as catalyst, a mixture of 2 mol of lanthanum orthophosphate and one mote of orthophosphoric acid. The degree of conversion of the dinitrile compounds is

62%. The yield of diesters is 3%. It was found that the reaction medium comprises cyanoesters, corresponding to an intermediate product capable of being converted to diesters. The yield of cyanoesters is 2%.
A third test was carried cut using, as catalyst, (anatase) titanium oxide. The conversion of the dinitrile compounds is 78%. The yield of diesters is 3%, The reaction medium additionally comprises 15% of cyanoesters and 20% of a mixture of imides.
Synthesis of the diesters In 2 stages
Example 3
1 ml/h of a mixture of dinitriles and 1 ml/h of water are coinjeded, using 2 syringe drivers, over a catalytic fixed bed, composed of 4 ml of (anatase) titanium oxide placed between 2 layers of 5 ml of glass powder, heated to 275^C and swept by a 3 l/h nitrogen stream. At the outlet of the reactor, the gases are condensed in a receiver placed in an ice bath. After reacting for 6 h, the products obtained are analysed by gas chromatography. For a conversion of the dinitriles of 97%, a yield of mixed imides of 94% is then obtained.
Example 4
1 g of a mixture of imides and 10 ml of methanol are introduced into a reactor and 0.2 g of anatase titanium oxide is added. The reaction mixture is heated under autogenous pressure at 250°C for 5 hours. After cooling and filtering off the catalyst, the medium is analysed by gas chromatography. For a conversion of imides of 90%, the yield of dimethyl esters is 60%.
Example 5
1 g of a mixture of imides and 10 miof 1-propanol are introduced into a reactor and 0.2 g of
anatase titanium oxide Is added. The reaction mixture is heated at 250*'C under autogenous
pressure for 5 hours. After cooling and filtering off the catalyst, the reaction medium is analysed by
gas chromatography. For a conversion of imides of 55%, a yield of dipropyl esters of 40% is
obtained.
Example 6
1 g of a mixture of imides and 10 ml of 1-butanoI are introduced into a reactor and 0.2 g of
anatase titanium oxide is added. The reaction mixture is heated at 250°C under autogenous
pressure for 5 hours. After cooling and filtering off the catalyst, the reaction medium is analysed by
gas chromatography. For a conversion of imides of 50%, a yield of dibutyl esters of 38% is
obtained.

Example 7
1 g of a mixture of imides and 10 ml of isobutyl alcohol are introduced into a reactor and 0.2 g of
anatase titanium oxide is added. The reaction mixture is heated at 250'C under autogenous
pressure for 5 hours. After cooling and filtering off the catalyst, the reaction medium is analysed by
gas chromatography. For a conversion of imides of 52%, a yield of diisobutyl esters of 40% is
obtained.
Example 8 in the gas phase
A solution composed of 1 g of a mixture of imides in solution in 8 ml of methanol is injected at a flow rate of 5 ml/h over a catalytic bed, composed of 4 ml of (anatase) titanium oxide placed between 2 layers of 5 ml of glass powder, heated to 275'C and swept by a 3 l/h nitrogen stream, At the outlet of the reactor, the gases are condensed in a receiver placed in an ice bath. After reacting for 6 hours, the products obtained are analysed by GC. For a conversion of imides of 62%, a yield of dimethyl esters of 30% is obtained.
Example 9
A solution composed of 1 g of a mixture of imides in solution in 8 ml of 1-pentanol is injected at a flow rate of 5 ml/h over a catalytic bed, composed of 4 ml of (anatase) titanium oxide placed between 2 layers of 5 ml of glass powder, heated to 275°C and swept by a 3 i/h nitrogen stream. At the outlet of the reactor, the gases are condensed in a receiver placed in an ice bath. After reacting for 6 hours, the products obtained are analysed by GC. For a conversion of imides of 70%, a yield of dipentyl esters of 45% is obtained.


Claims
1. Process for the manufacture of diester compounds by reaction between an imide compound of following general formula (I):

5. Process according to one of claims 1 to 3, characterized in that the amount of alcohol ROH and of water employed are determined in order to have a molar ratio R of the number of molecutes of alcohol to the number of molecules of water greater by at least 10% than a

stoichiometric ratio Rstoich of the stoichiometric number of molecules of alcohol for converting the imide formed from the djnitrile to diesters to the stoichiometric number of molecules of water necessary to hydrolyse the dinitrile compound to imide compound.
6. Process according to Claim 5, characterized in that the ratio R is greater than 1.1, advantageously less than 20 and preferably less than or equal to 10.
7. Process according to one of Claims 2 to 7, characterized in that the dinitriie compounds are chosen from the group consisting of methylglutaronitrile. ethylsucclnonitriie, adiponitrile and their mixtures.
8. Process according to one of Claims 1 to 7, characterized in that the alcohol is chosen from the group consisting of methanol, propanol, isopropanol, benzyl alcohol, ethanol, n-butanol, isobutanol, pentanols, cyclohexanol, hexanol, isooctanol, 2-6thylhexanol and their mixtures.
9. Process according to one of Claims 2 to 8, characterized in that the hydrolysis reaction is carried out at a temperature of less than SOOX, preferably between 250 and 450'C.
10. Process according to one of Claims 2 to 9, characterized in that the molar ratio of the water to the nitrile compound is between 1 and 10 and preferably between 2 and 5.
11. Process according to one of Claims 2 to 10, characterized in that the solid catalyst is chosen from metal oxides, such as alumina, heternnnlyaclds^ zeolites of pentasil and faujasite type, clays, metal phosphates, titanium oxide, silica/aJumina mixtures and the like.
12. Process according to Claim 11 characterized in that the clay is chosen from kaolins, serpentines, smectites or montmorillonites, illites or micas, glauconites, chlorites or vermlculites, attapulgites or sepiolites, mixed-layer clays, allophanes or imogolites and high-alumina clays.
13. Process according to Claim 12, characterized in that the clay is a montmorilJonite.
14. Process according to either of Claims 12 and 13, characterized in that the clay is bridged.
15. Process accon:ling to Claim 11, characterized in that the catalyst is a particulate catalyst obtained by shaping at least one simple or mixed inorganic oxide of at least one element chosen from the group consisting of silicon, aluminium, titanium, zirconium, vanadium, niobium.

tantalum, tungsten, molybdenum, iron and rare earth metals and In that it comprises at least one macroporosity characterized by a pore volume, corresponding to the pores with a diameter of greater than 500 A, of greater than or equal to 5 mi/100 g.
16. Process according to Claim 15, characterized in that the particulate catalyst exhibits a specific surface of greater than 10 m^/g and a total pore volume of greater than or equal to 10 ml/100 g, the pore volume corresponding to the pores \N\Vn a diameter of greater than 500 A being greater than or equal to 10 ml/100 g.
17. Process according to Claim 15 or 16, characterized in that the catalyst exhibits a specific surface of greater than 50 m^/g.
18. Process according to one of Claims 15 to 17, characterized in that the catalyst exhibits a total pore volume of greater than or equal to 20 ml/100 g with a pore volume, corresponding to the pores with a diameter of greater than 70 A, of greater than or equal to 20 ml/100 g.
19. Process according to one of Claim 15 to 18, characterized in that the particulate catalyst is an aluminium oxide.
20. Process according to one of Claims 15 to 19, characterized in that the particulate catalyst comprises at least one element chosen from the list consisting of silicon, titanium, zirconium, vanadium, niobium, tantalum, tungsten, molybdenum, iron and rare earth metals or at least CM£ oxygen compound of at least one element chosen from the group consisting of the elements belonging to Groups 1 to 16 of the Periodic Table of the Elements (new Table), this list also including the rare earth metals, deposited or adsorbed on the particulate catalyst formed of simple or mixed inorganic oxide.
21. Process according to claim 11, characterized in that the catalyst is a metal phosphate of general formula:
(P04)nHhM. (Imp)p
in which:
> M represents a divalent, trivaient, tetravaient or pentavalent element chosen from Groups 2a,
3b, 4b, 5b, 6b, 7b, 8, 2b, 3a, 4a and 5a of the Pen'odic Table of the Elements or a mixture of
several of these elements or M=0,

> Imp represents a basic impregnation compound composed of an alkali metal or alkaline earth
metal or of mixtures of several of these metals, in combination with a counteranion in order to
provide electrical neutrality,
> n represents 1, 2 or 3,
> h represents 0,1 or 2,
> p represents a number between 0 and 1/3 and corresponds to a molar ratio of the
impregnating material Imp to the impregnated material (P04)nHhWl-
22. Process according to Claim 11, characterized in that the catalyst is a pyrophosphate of rare
earth metals.
23. Process according to Claim 11, 21 or 22, characterized in that the catalyst is a mixture of
pyrophosphates of rare earth metals and of orthophosphates of rare earth metals.
24. Process according to either of Claims 11 and 21, characterized in that the catalyst is a mixture
of orthophosphates of rare earth metals and of phosphoric add.


Documents:

0322-chenp-2009 abstract.pdf

0322-chenp-2009 claims.pdf

0322-chenp-2009 correspondence-others.pdf

0322-chenp-2009 description(complete).pdf

0322-chenp-2009 form-1.pdf

0322-chenp-2009 form-18.pdf

0322-chenp-2009 form-3.pdf

0322-chenp-2009 form-5.pdf

0322-chenp-2009 pct.pdf

322-CHENP-2009 AMENDED PAGES OF SPECIFICATION 23-10-2013.pdf

322-CHENP-2009 AMENDED CLAIMS 23-10-2013.pdf

322-CHENP-2009 CORRESPONDENCE OTHERS 16-07-2013.pdf

322-CHENP-2009 EXAMINATION REPORT REPLY RECEIVED 23-10-2013.pdf

322-CHENP-2009 FORM-3 23-10-2013.pdf

322-CHENP-2009 OTHER PATENT DOCUMENT 23-10-2013.pdf

322-CHENP-2009 OTHERS 23-10-2013.pdf

322-CHENP-2009 POWER OF ATTORNEY 23-10-2013.pdf

322-CHENP-2009 CORRESPONDENCE OTHERS 20-08-2013.pdf


Patent Number 258002
Indian Patent Application Number 322/CHENP/2009
PG Journal Number 48/2013
Publication Date 29-Nov-2013
Grant Date 27-Nov-2013
Date of Filing 19-Jan-2009
Name of Patentee RHODIA OPERATIONS
Applicant Address 40, RUE DE LA HAIE-COQ,F-93306 AUBERVILLIERS,
Inventors:
# Inventor's Name Inventor's Address
1 JACQUOT, ROLAND, 15 RUE DES PINSONS, F-69340 FRANCHEVILLE,
2 LECONTE, PHILIPPE, 43 RUE SAINTE-BEUVE, F-69330 MEYZIEU,
3 MARION, PHILIPPE, 140, ROUTE DU BUYE, F-69390 VERNAISON,
PCT International Classification Number C07C67/20
PCT International Application Number PCT/FR07/01140
PCT International Filing date 2007-07-05
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 0606510 2006-07-18 France