Title of Invention

A PROCESS FOR THE PREPARATION OF ORGANIC POLYSULPHIDE

Abstract

The invention relates to a process for the manufacture of organic disulphides and polysulphides. According to the invention, an organic disulphide or polysulphide of formula R-Sp-R, in which p > 2, is prepared by reacting sulphur with a mercaptan of formula R-SH or a polysulphide of lower sulphur order to convert it into polysulphide of higher order, or reacting a mercaptan with an organic polysulphide of high sulphur order to convert it into polysulphide of lower sulphur order, in the presence, as catalyst, of a resin based on polystyrene-divinylbenzene (PS-DVB) functionalized with ethylenediamine or polyethylenepolyamine groups of the specified formula. The process according to the invention provides an improved degree of conversion of the reactants and/or a faster reaction rate when compared with the prior art.

Full Text

The present invention relates to a process for the preparation of organic polysulphides (including disulphides), of formula R-Sp-R (in which p £ 2) and more particularly to their production by reaction of mercaptans with sulphur, in the presence of basic resins which act as catalysts, according to the reaction: In the presence of such basic resins, organic disulphides and polysulphides can be converted into polysulphides of increased sulphur order by reaction with sulphur. Similarly, in the presence of such basic resins, organic polysulphides can be converted into polysulphides of reduced sulphur order by reaction with mercaptans. Thus, European patent specification EP-A-337,837 teaches the preparation of organic disulphides and polysulphides catalysed by organic anion exchange resins containing tertiary amine or quaternary ammonium functional groups (active in hydroxide form). Such resins, generally in the form of grains or beads which are insoluble in liquid reaction media and are thus easy to separate out at the end of the reaction, allow organic disulphides and polysulphides to be obtained by reaction of elemental sulphur with mercaptans and also allow organic polysulphides of increased sulphur order to be obtained by reaction of elemental sulphur with organic polysulphides of lower sulphur order. According to French patent specification FR 2,742,144, the use of basic resins containing a primary amine function makes it possible, when compared with resins containing a tertiary amine function, to obtain a better degree of conversion of the reactants and/or a faster rate of reaction. Similarly, French patent specification FR 2,742,145 recommends the use of strongly basic resins containing a guanidine or amidine function, which also makes it possible, when compared with resins containing a tertiary amine function, to obtain a better degree of conversion of the reactants and/or a faster reaction rate. The aim of the present invention is to further improve these results in order to obtain a better degree of conversion of the reactants and/or a faster reaction rate. This aim is achieved by the use of resins functionalized with ethylenediamine or polyethylenepoly-amine groups. According to the present invention there is provided a process for the preparation of an organic polysulphide having at least two sulphide groups of the formula R-Sp-R, in which each R, which may be the same or different, represents an organic group and p ^ 2, which process comprises reacting sulphur with a mercaptan of formula R-SH or a polysulphide to convert it into polysulphide of increased sulphur order, or reacting a mercaptan with an organic polysulphide to convert it into polysulphide of reduced sulphur order, in the presence, as catalyst, of a resin based on poly-styrene-divinylbenzene (PS-DVB) functionalized with ethylenediamine or poly-ethylenepolyamine groups and represented by the general formula (I) : in which: represents the PS-DVB resin support, each of R1, R2, R3 and R4, which may be the same or different, represents a hydrogen atom or an alkyl, cycloalkyl, aryl or arylalkyl radical, n is an integer of from 1 to 6, and m does not exceed n and is 0 or an integer up to 5, The resins which may suitably serve as starting materials for the preparation of the resins containing an ethylenediamine or polyethylenepolyamine function of general formula (I) can be PS-DVB copolymers or chloromethyl PS-DVB copolymers which, by appropriate chemical reactions described below, are converted into resins containing an ethylenediamine or polyethylenepolyamine function according to the invention. With a low content of divinylbenzene (0.5 to 7% by weight) as crosslinking agent, copolymers of the gel type are obtained, whereas with higher DVB contents, macrocrosslinked resins of macroporous structure can be obtained. The DVB content can be from 0.5% to 60% by weight relative to the total weight of the PS-DVB copolymer. Preferably, the starting materials and, consequently, the resins of general formula (I) are macrocrosslinked and of macroporous structure, since these characteristics entail better catalytic activity than is the case with resins of gel type. These PS-DVB resins can be chloromethylated with chloromethyl ether, according to known techniques which are described in the literature, to variable chlorine contents generally ranging from 1 to 2 0% by weight of chlorine relative to the weight of chloromethyl resin. The resins according to the invention can be prepared, according to known amination techniques described in the literature, by reaction of a chloromethyl PS-DVB resin with ethylenediamine or a polyethylenepolyamine of general formula (II): in which m, n, R1, R2, R3 and R4 are as defined above. In general, an excess of the amine (II) is dissolved in a solvent for swelling the chloromethyl resin (for example tetrahydrofuran); the chloromethyl resin is introduced into this solution and the reaction mixture is stirred for a period ranging from a few hours to several days (generally from 4 hours to 4 days) at a temperature which can range from about 20°C to the boiling point of the solvent, but must not exceed the stability limit temperature of the resin (generally 100°C). At the end of the reaction, the resin is washed with sodium hydroxide and then with a solvent of low boiling point (for example acetone) in order to help it to dry. Preferably, an amine of formula (II) is used, in which n is an integer of from 1 to 5, m is 0 and R1, R2 and R4 are hydrogen atoms. The radicals R of the organic mercaptans, disulphides and polysulphides may be hydrocarbon radicals, generally alkyl, cycloalkyl, aryl, arylalkyl or alkylaryl groups. These radicals R can be substituted by one or more functional groups such as, for example, halogen atoms and -OH, -OR', -SR', NR'R", -CN, -CHO, -COR' and -COOR' groups, the symbols R' and R" denoting ci to C12 aliphatic radicals or cycloaliphatic, aromatic or alkylaromatic radicals. The present invention applies in particular to the production of dialkyl disulphides and polysulphides containing from 2 to 4 0 carbon atoms in total, such as, for example, dimethyl, diethyl, dipropyl, dibutyl, dipentyl, dihexyl, diheptyl, dioctyl, didecyl and didodecyl disulphides and polysulphides. It also applies to the preparation of cycloalkyl disulphides and polysulphides such as, for example, dicyclohexyl disulphide and polysulphides, as well as to the preparation of aromatic disulphides or polysulphides, such as diphenyl disulphide and polysulphides. The catalytic activity of the resins used in the present invention appears at very low resin contents. Advantageously, the resin is present in an amount ranging from 0.01 to 20 parts by weight per 100 parts by weight of reaction mixture, including resin. The process according to the invention comprises a reaction which may be carried out at a temperature of from -10°C to 150°C. The temperature is preferably from + 10°C to 120°C. The reaction may be performed at atmospheric pressure or at higher pressures which may reach 50 bar. In the case of relatively non-volatile reactants of low vapour pressure, the reaction may be performed at pressures below atmospheric pressure, optionally in the presence of an inert gas, such as nitrogen. The mereaptan/sulphur molar ratio depends on the nature of the mercaptan used and on the product to be prepared (disulphide or polysulphide). Advantageously, this ratio is from 0.3 to 10 and preferably from 0.4 to 6. When an organic polysulphide is used at the start in order to convert it into organic polysulphide of reduced sulphur order, for example into a trisulphide R-S3-R or disulphide R-S2-R by the action of the corresponding mercaptan, a mercaptan/polysulphide molar ratio ranging from 2 to 10 is advantageously used. The production of organic polysulphides (including disulphides) in the presence of PS-DVB resins containing ethylenediamine or polyethylenepolyamine functions can be carried out in a stirred or tubular reactor, according to a batchwise process, either by loading the reactants before reacting them, or by gradual addition of one of the reactants into the reactor, or alternatively according to a continuous process with controlled addition of the reactants. In the case where sulphur is one of the reactants (the other being a mercaptan or a polysulphide), it may be introduced in liquid or solid form. Accordingly, the present invention provides a process for the preparation of an organic polysulphide having at least two sulphide groups of the formula R-Sp-R, in which each R, which may be the same or different, represents an organic group and p > 2, which process comprises reacting sulphur with a mercaptan of formula R-SH or a polysulphide to convert it into polysulphide of increased sulphur order, or reacting a mercaptan with an organic polysulphide to convert it into polysulphide of reduced sulphur order, in the presence, as catalyst, of a resin based on polystyrene-divinylbenzene (PS-DVB) functionalized with ethylenediamine or polyethylenepolyamine groups and represented by the general formula (I): represents the PS-DVB resin support, each of R1, R2, R3 and R4, which may be the same or different, represents a hydrogen atom or an alkyl, cycloalkyl, aryl or arylalkyl radical, n is an integer of from 1 to 6, and m does not exceed n and is 0 or an integer up to 5. The present invention is further described in the following Examples which are included for purely illustrative purposes. EXAMPLE 1 : Preparation of the resins according to the invention A chloromethyl PS-DVB macroporous resin having the following characteristics was used: specific surface : 22.5 m /g of dry resin average pore diameter : 2 nm pore volune 0.69 ml/g mmol of chlorine/g of resin : 5.4 mmol/g of dry resin IU g ot dry chloromethyl resin (i.e. 54 mmol of chlorine) were weighed out and placed in contact, under a nitrogen atmosphere, with 6.48 g (108 mmol) of ethylenediamine diluted in 130 ml of tetrahydrofuran (THF) predried over molecular sieves. The reaction mixture thus obtained was stirred mechanically for 48 hours at 60°C. After cooling to 20°C, the resin was filtered off and washed successively with THF, then with 20 ml of aqueous 10% sodium hydroxide solution, next with water until neutral and finally with acetone, before being dried under vacuum at 60°C to a constant weight. A PS-DVB resin containing ethylenediamine functions (referred to hereinbelow as EDA resin) containing 7.6% by weight of nitrogen, i.e. 2.70 mmol of ethylenediamine per gram of dry resin, was thus obtained. Working as above, but replacing the ethylene-diamine with an equivalent molar amount of diethylene-triamine (11.2 g) , of triethylenetetraamine (15.77 g), of tetraethylenepentaamine (20.41 g) or of pentaethylene-hexaamine (25.06 g), other resins according to the invention, identified as DETA, TETA, TEPA and PEXA respectively, were obtained. Their characteristics are collated in the following table. The characteristics of PS-DVB resins according to the prior art, namely - a resin containing tetramethylguanidine functions (referred to hereinbelow as TMG resin) prepared as above, but replacing the ethylenediamine with 12.5 g of tetramethylguanidine; - a resin containing triazabicyclodecene functions (referred to hereinbelow as TBD resin) prepared as described on pages 2 3 and 2 4 of patent application FR 2,742,145, are also given in this table. EXAMPLE 2 : Synthesis of di(tert-dodecyl) trisulphide by reaction of tert-dodecyl mercaptan with sulphur in the presence of basic resins Tests for the production of bis(tert-dodecyl) trisulphide were carried out under identical experimental conditions, using the EDA, DETA, TETA, TEPA and PEXA resins according to the invention as catalysts. Comparative tests were also carried out using the resins of the prior art, namely: - Amberlyst A21 resin from Rohm & Haas, which is a macroporous-type PS-DVB resin containing -CH2N(CH3)2 functions, having a specific surface of 39.8 m2/g and 4.4 mmol of tertiary amine functions/g of dry resin; - Purolite A109 resin, which is a macrocrosslinked PS-DVB resin of macroporous structure containing -CH2NH2 functions (4.3 mmol of NH2/g of dry resin); - the TMG and TBD resins according to patent application FR 2,742,145. These tests were carried out in apparatus comprising a 250 ml glass jacketed reactor equipped with: - a sinter before the drainage valve, - an inlet for introducing nitrogen via a dip tube ending with a sinter (flow rate of nitrogen controlled by a ball flowmeter), - a water-cooled condenser connected to the tume cupboard vacuum via a bubble counter containing oil, - a thermostatically regulated bath allowing oil to be circulated in the jacket, - a glass stirrer ending with a PTFE anchor-paddle and fitted with a stirrer motor with a tachometer, - a thermometer probe in a glass sheath. After the reactor had been placed under a nitrogen atmosphere, 6 g or 15 g of resin (i.e. a catalyst/RSH ratio = 4% or 10% respectively) were introduced therein, followed by 151.2 g (750 mmol) of tert-dodecyl mercaptan (TDM). The reactor was then heated to 90°C, after which 24 g (750 mmol) of sulphur were added in a single portion. With the stirring continuing at 500 rev/min, the sulphur dissolved in about 30 minutes. After switching on the nitrogen bubbling (flow rate = 12 1/h) for the entire duration of the reaction, samples were taken over time (t = 0 at the time of introduction of the sulphur) in order to determine the residual mercaptan content (% by mass) by argentimetry and the free sulphur content by HPLC; the residual mercaptan content makes it possible to determine the degree of conversion of the TDM. At the end of the reaction, the polysulphide is filtered while hot (40°C) through the reactor sinter and the resin is ready to be reused with a fresh load of TDM and sulphur. The results obtained with the various resins are collated in the following table. Examination of these results shows that the resins containing ethylenediamine or polyethylenepoly-amine functions according to the invention (Tests 7 to 14) have higher activity than resins containing tertiary amine functions (Tests 1 and 2), primary amine functions (Tests 3 and 4) or guanidine functions (Tests 5 and 6). EXAMPLE 3 : Synthesis of bis(tert-dodecyl) pentasulphide by reaction of tert-dodecyl mercaptan with sulphur in the presence of basic resins 6 g of resin (i.e. a catalyst/RSH ratio = 4%) were introduced into the reactor, placed beforehand under a nitrogen atmosphere, followed by 151.2 g (750 mmol) of TDM, in the same apparatus as in Example 2. After bringing the reactor to 90°C, 48 g (1.5 mol) of sulphur were introduced therein in three portions with intervals of 10 minutes. With the stirring maintained at 500 rev/min, the sulphur dissolved completely in about 45 minutes. After switching on the nitrogen bubbling (flow rate = 6 1/h) for the entire duration of the reaction, the process was then carried out as in Example 2. The test results are collated in the following table. Examination of this table shows that the resin according to the invention (Test 18) gives better results than the resins of the prior art (Tests 15 to 17). WE CLAIM: 1. A process for the preparation of an organic polysulphide having at least two sulphide groups of the formula R-Sp-R, in which each R, which may be the same or different, represents an organic group and p ≥ 2, which process comprises reacting sulphur with a mercaptan of formula R-SH or a polysulphide to convert it into polysulphide of increased sulphur order, or reacting a mercaptan with an organic polysulphide to convert it into polysulphide of reduced sulphur order, in the presence, as catalyst, of a resin based on polystyrene-divinylbenzene (PS-DVB) functionalized with ethylenediamine or polyethylenepolyamine groups and represented by the general formula (I): represents the PS-DVB resin support, each of R1, R2, R3 and R4, which may be the same or different, represents a hydrogen atom or an alkyl, cycloalkyl, aryl or arylalkyl radical, n is an integer of from 1 to 6, and m does not exceed n and is 0 or an integer up to 5. 2. The process according to claim 1, in which the resin of formula I is a macrocrosslinked resin of macroporous structure. 3. The process according to claim 1 or 2, in which the radicals R of the organic mercaptans, and polysulphides are alkyl, cycloalkyl, aryl, arylalkyl or alkylaryl groups unsubstituted or substituted by one or more functional groups. 4. The process according to anyone of claims 1 to 3, in which the resin is present in an amount of from 0.01 to 20 parts by weight per 100 parts by weight of reaction mixture, including resin. 5. The process according to anyone of claims 1 to 4, in which the reaction is carried out at a temperature between -10°C and 150°C. 6. The process according to claim 5, in which the reaction is carried out at a temperature of between +10°C and 120°C. 7. The process according to anyone of claims 1 to 6 for the preparation of a polysulphide from a mercaptan and sulphur, in which the mercaptan/sulphur molar ratio is between 0.3 and 10. 8. The process according to claim 7, in which the mercaptan/sulphur molar ratio is between 0.4 and 6. 9. The process according to anyone of claims 1 to 6 for the preparation of an organic polysulphide of reduced sulphur order from an organic polysulphide of higher sulphur order and a mercaptan, in which the mercaptan/polysulphide molar ratio is from 2 to 10. 10. The process according to anyone of the preceding claims, in which the resin support is a chloromethyl PS-DVB resin. 11. A process for the preparation of organic polysulphide substantially as herein described with particular reference to examples herein 2 and 3. 12. An organic polysulphide of formula R-Sp-R (in which p 5L2) when prepared by the process as claimed in any one of the preceding claims.

Documents:

0058-mas-1999 abstract-granded.pdf

0058-mas-1999 claims-granded.pdf

0058-mas-1999 description (complete)-granded.pdf

58-mas-1999-abstract.pdf

58-mas-1999-claims.pdf

58-mas-1999-correspondance others.pdf

58-mas-1999-correspondance po.pdf

58-mas-1999-description complete.pdf

58-mas-1999-form 1.pdf

58-mas-1999-form 26.pdf

58-mas-1999-form 3.pdf

58-mas-1999-form 4.pdf