Title of Invention | A PROCESS FOR THE PREPARATION OF POLY(ACYLSULFIDE) FOR INDUSTRIAL APPLICATIONS |
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Abstract | A process for the preparation of poly(acyl sulfide) is disclosed whereby acid dichloride is condensed with alkali metal sulfide in presence of phase transfer catalyst, thereby forming the polymer in one step reaction. |
Full Text | The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed The present invention relates to a process for the preparation of poly(acyl sulfide) for industrial applications. More particularly, the present invention relates to a process for the preparation of poly(acyl sulfide) as a single step reaction using phase transfer catalyst. The polymers of the present invention have enormous potential applications as adhesive in footwear and leather goods industries. These polymers also find applications as fuel binder in rocket propeilant. Conventionally, poly (acyl sulfide) polymer is prepared, as reported by 'Kricheldorf et al (Die Makromolekulare Chemie 158, 223-239, 1972), by reacting dithiodicarboxylic acid trimethyl silyl ester with its corresponding acid dichloride in the presence of pure toluene for 1 hour, followed by the removal of toluene and chloro trimethylsilane by distillation and subsequent treatment of the resulting viscous liquid with petroleum ether in presence of P^io to produce the polymer. The major limitation associated with the above reaction is that dithiodicarboxylic acid trimethyl silyl ester, which is the starting material for synthesizing the polymer, is not readily available, thereby necessitating its synthesis as an additional step. The synthesis of dithiodicarboxylic acid trimethyl silyl ester involves reacting hexamethyl disilthiane, dissolved in carbon tetrachloride solution, with an acid dichloride at 0°C followed by ageing for 12 hrs at the same temperature and subsequent removal of the solvent by distillation at 21°C and fractional distillation using vacuum pump. Another limitation associated with the preparation of the polymer is that the polymerization reaction requires pure toluene, which can be prepared only by using sodium wire, which requires additional infrastructural facilities such as mantle and glass apparatus. Moreover, the requirement of maintaining the constant temperature of the bath at 0°C requires additional cooling bath. Thus the two-stage reaction on the one hand and the additional infrastructural facilities on the other hand add to the total cost of production of the poly(acyl sulfide) polymer. It necessitates exploring possibilities to prepare the polymer by a simpler process to achieve significant reduction in the manufacturing cost. No other prior art is available on the process for preparation of the polymer. The main object of the present invention is to provide a process for the preparation of poly(acyl sulfide) for industrial applications, which obviates the drawbacks as detailed above. Another object of the present invention is to provide a single step polymerization process to prepare the polymer. Yet another object of the present invention is to identify readily available raw materials to prepare the polymer. Accordingly the present invention provides a process for the preparation of poly(acyl sulfide) for industrial applications, which comprises reacting alkali metal sulfide with varying combinations of an acid dichlorides in the presence of phase transfer catalyst The process for the preparation of poly(acyl sulfide) which comprises i. polymerising 1-1.2 mole of alkali metal sulfide, per mole of dichloride, dissolved in 4-50 % w/v, of water, with aliphatic acid dichloride, either as such or dissolved in 5-10 % w/v of conventional organic solvent, or aromatic acid dichloride, either individually or in any combination with aliphatic acid dichloride, dissolved in 5-10 % w/v of conventional organic solvent, in the presence of 0.25-5.00 % w/w of known phase transfer catalyst at a temperature in the range of 15-35 °C for a minimum period of two hours by conventional method, ii. subjecting the reaction mixture, as formed in step(i), to separation by conventional method followed by purification of the resulting substance by conventional method using 1-5% w/w, of moisture absorbing agents and/or 5-20% w/w, of non- solvent and subsequent drying by known method at 15-50°C to obtain poly(acyl sulfide) polymer. In an embodiment of the present invention, the alkali metal sulfide used may be selected from sodium sulfide nonahydrate, potassium sulfide. In another embodiment of the present invention, the aromatic acid dichloride used may be selected from terephthaloyl chloride, isophthaloyl chloride, 4,4-biphenyl dicarboxyloylchloride, 2,6- Naphthalene dicarboxyloylchloride, 1,4-Naphthalene dicarboxyloylchloride, either individually or in any combinations. In yet another embodiment of the present invention, the aliphatic acid dichloride used may be selected from adipoyl chloride, sebacoyl chloride, dodecane dicarboxyloylchloride, either individually or in any combinations. In still another embodiment of the present invention, the conventional organic solvent used may be selected from carbontetrachloride, cyclohexane, dichloromethane, chloroform, toluene, tetrahydrofuran. In yet another embodiment of the present invention the phase transfer catalyst used may be selected from Tetrabutylammonium bromide, Tetrabutylammoniumhydrogen sulphate, Cetyltrimethylammonium bromide, Cetyltributylphosphonium bromide, dibenzo-18-Crown-6. In still another embodiment of the present invention, the known method for separation used may be such as decanting, funnel-separation, and filtration. In yet another embodiment of the present invention, the non-solvent used may be selected from methanol, ethanol, petroleum ether, hexane, heptane. In still another embodiment of the present invention, the moisture absorbing agent used may be selected from anhydrous sodium sulfate, anhydrous magnesium sulfate. In yet another embodiment of the present invention, the known method for drying used may be such as vacuum oven drying, vacuum pump drying. The process of the present invention is described below in detail. 1.0-1.20 mole of an alkali metal sulfide per mole of acid dichloride is dissolved in 4-50 % w/v, of water. It is then polymerised with aliphatic acid dichloride, which is used either as such or as a solution formed by dissolving the same in 5-10 %.w/v of conventional organic solvent, or aromatic acid dichloride, either individually or in any combination with aliphatic acid dichloride, whereby the acid dichloride is dissolved in 5-10 % w/v of conventional organic solvent. The polymerisation reaction is continued in the presence of 0.25-5.00 % w/w of known phase transfer catalyst at a temperature in the range of 15-35 °C for a minimum period of two hours by conventional method. The resulting heterogeneous mixture is subjected to separation by known method, followed by purification of the separated substance by conventional method. While the separated solution generated out of aliphatic acid dichloride, dissolved in solvent, is purified by subjecting the same to treatment with 1-5% w/w, of moisture absorbing agent, followed by 5-20% of known non-solvent, the solid mass generated out of other combinations of acid dichlorides is treated with 5-20% of known non-solvent. Finally the resulting product is dried by conventional method at a temperature in the range of 15-50°C to obtain poly(acyl sulfide) polymer. The novelty and non-obviousness of the present invention lies in reacting alkali metal sulfide with varying combinations of acid dichlorides in the presence of phase transfer catalyst, whereby the polymer formed by a single step reaction, is subjected to purification depending on the type of acid dichlorides used, thereby suggesting a simple as well as cost effective method for producing the polymer. The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention EXAMPLE-1 8.6464 g of sodium sulfide nonahydrate was dissolved in 18 ml of water taken in a round bottom flask. 6.08 g of terephthaloyl chloride was taken separately in 60 ml of chloroform solution and the resulting solution was added to the round bottom flask with continuous stirring. The temperature of the contents of the flask was maintained at 15°C. 0.30 g of tetrabutylammoniumhydrogen sulphate was then added to the flask with vigorous stirring while maintaining the temperature at 15°C. After a period of 2 hrs, two distinct layers were found to be formed in the reaction mixture contained inside the flask. This mixture was filtered using filter paper and the filtrate was rejected. The polymer, collected in the filter paper as residue was washed three times with 1 Oml of water. The aqueous washed polymer was then washed with 20ml of methanol. The resulting solid precipitate, formed on the filter paper, was vacuum pump dried at 50°C for 1 hour to get the poly(acyl sulfide) polymer, which was collected and stored in a plastic container. EXAMPLE-2 1.2126g of pottasium sulfide was dissolved in 15 ml of water taken in a round bottom flask. 2.03 g of isophthaloyl chloride was taken separately in 23 ml of dichloromethane solution and the resulting solution was added to the round bottom flask with continuous stirring. The temperature of the contents of the flask was maintained at 20°C. 0.0098g of tetrabutylammonium bromide was then added to the flask with vigorous stirring while maintaining the temperature at 20°C. After a period of 2 hrs, two distinct layers were found to be formed in the reaction mixture contained inside the flask. This mixture was filtered using filter paper and the filtrate was rejected. The polymer, collected in the filter paper as residue was washed three times with 10ml of water. The aqueous washed polymer was then washed with 20ml of ethanol. The resulting solid precipitate, formed on the filter paper, was vacuum oven dried at 30 °C for 1 hour to get the poly(acyl sulfide) polymer, which was collected and stored in a plastic container. EXAMPLE-3 1.1 Og of pottasium sulfide was dissolved in 15 ml of water taken in a round bottom flask. 2.53 g of 2,6-Naphthalene dicarboxyloyl chloride was taken separately in 46 ml of chloroform solution and the resulting solution was added to the round bottom flask with continuous stirring. The temperature of the contents of the flask was maintained at 25°C. 0.025g of cetyltrimethylammonium bromide was then added to the flask with vigorous stirring while maintaining the temperature at 25°C. After a period of i 2 hrs, two distinct layers were found to be formed in the reaction mixture contained inside the flask. This mixture on decanting yielded the polymer. The polymer, thus collected was washed three times with 10ml of water. The aqueous washed polymer was then washed with 20ml of methanol. The resulting solid precipitate, formed was vacuum pump dried at 30 °C for 1 hour to get the poly(acyl sulfide) polymer, which was collected and stored in a plastic container. EXAMPLES 4.20 g of sodium sulfide nonahydrate was dissolved in 15 ml of water taken in a round bottom flask. 2.745 g of adipoyl chloride was taken separately in 45 ml of cyclohexane solution and the resulting solution was added to the round bottom flask with continuous stirring. The temperature of the contents of the flask was maintained at 30°C. 0.05g of cetyltributylphosphonium bromide was then added to the flask with vigorous stirring while maintaining the temperature at 30°C. After a period of 20 hrs, two distinct layers were found to be formed in the reaction mixture contained inside the flask. The organic layer was separated from the aqueous layer using separating funnel and was washed three times with 20 ml of water. This was then dried over Ig of anhydrous magnesium sulphate for 1 hr to remove the moisture. The moisture free liquid, obtained thereby, was subjected to distillation to remove cyclohexane and 20 ml of heptane was poured on the resulting viscous liquid with stirring. The precipitate, formed thereby as a solid mass, was vacuum oven dried at 30 °C for 1 hour to get the poly(acyl sulfide) polymer, which was stored in a plastic container. EXAMPLE-5 2.84 g of sodium sulfide nonahydrate was dissolved in 10 ml of water taken in a round bottom flask. 2.40 g of sebacoyl chloride was taken separately in 50 ml of toluene solution and the resulting solution was added to the round bottom flask with continuous stirring. The temperature of the contents of the flask was maintained at 35°C. 0.075 g of dibenzo-18-crown 6 was then added to the flask with vigorous stirring while maintaining the temperature at 35°C. After a period of 24 hrs, two distinct layers were found to be formed in the reaction mixture contained inside the flask. The organic layer was separated from the aqueous layer using separating funnel and was washed three times with 20 ml of water. This was then dried over Ig of anhydrous sodium sulphate for 3 hrs to remove the moisture. The moisture free liquid, obtained thereby, was subjected to distillation to remove toluene and 20 ml of hexane was poured on the resulting viscous liquid with stirring. The precipitate, formed thereby as a solid mass, was vacuum oven dried at 30 °C for 1 hour to get the poly(acyl sulfide) polymer, which was stored in a plastic container. EXAMPLE-6 2.44 g of sodium sulfide nonahydrate was dissolved in 10 ml of water taken in a round bottom flask. 2.40 g of dodecane dicarbaxyloylchloride was taken separately in 30 ml of carbontetrachloride solution and the resulting solution was added to the round bottom flask with continuous stirring. The temperature of the contents of the flask was maintained at 30°C. 0.090 g of tetrabutylammcnium bromide was then added to the flask with vigorous stirring while maintaining the temperature at 30°C. After a period of 24 hrs, two distinct layers were found to be formed in the reaction mixture contained inside the flask. The organic layer was separated from the aqueous layer using separating funnel and was washed three times with 20 ml of water. This was then dried over Ig of anhydrous magnesium sulphate for 1 hrs to remove the moisture. The moisture free liquid, obtained thereby, was subjected to distillation to remove toluene and 20 ml of petroleum ether was poured on the resulting viscous liquid with stirring. The precipitate, formed thereby as a solid mass, was vacuum oven dried at 30 °C for 1 hour to get the poly(acyl sulfide) polymer, which was stored in a plastic container. EXAMPLE-7 2.84 g of sodium sulfide nonahydrate was dissolved in 15 ml of water taken in a round bottom flask. A mixture of 1.01 g of isophthaloyl chloride and 1.20 g of sebacoyl chloride was taken separately in 50 ml of dichloromethane solution and the resulting solution was added to the round bottom flask with continuous stirring. The temperature of the contents of the flask was maintained at 25°C. 0.060 g of tetrabutylammonium bromide was then added to the flask with vigorous stirring while maintaining the temperature at 25°C. After a period of 12 hrs, two distinct layers were found to be formed in the reaction mixture contained inside the flask. This mixture was filtered using filter paper and the filtrate was rejected. The polymer, collected in the filter paper as residue was washed three times with 10ml of water. The aqueous washed polymer was then washed with 20ml of ethanol. The resulting solid precipitate, formed on the filter paper, was vacuum pump dried at 40°C for 1 hour to get the poly(acyl sulfide) polymer, which was collected and stored in a plastic container. EXAMPLE-8 5.68 g of sodium sulfide nonahydrate was dissolved in 25 ml of water taken in a round bottom flask. A mixture of 3.60 g of terephthaloyl chloride and 1.20 g of adipoyl chloride was taken separately in 60 ml of chloroform solution and the resulting solution was added to the round bottom flask with continuous stirring. The temperature of the contents of the flask was maintained at 15°C. 0.12 g of cetyltributylphosphonium bromide was then added to the flask with vigorous stirring while maintaining the temperature at 15°C. After a period of 8 hrs, two distinct layers were found to be formed in the reaction mixture contained inside the flask. This mixture was filtered using filter paper and the filtrate was rejected. The polymer, collected in the filter paper as residue was washed three times with 10ml of water. The aqueous washed polymer was then washed with 20ml of methanol. The resulting solid precipitate, formed on the filter paper, was vacuum oven dried at 35°C for 1 hour to get the poly(acyl sulfide) polymer, which was collected and stored in a plastic container. The main advantages of the present invention are the following. 1. The process of the present invention is simple and economical. 2. The starting materials are readily available and do not require separate synthesis. 3. The polymerisation process of the present invention is a single step reaction. We claim: 1. A process for the preparation of poly(acyl sulfide) for industrial applications, which comprises (i) polymerising 1-1.2 mole of alkali metal sulfide, per mole of acid dichloride, dissolved in 4-50 % w/v, of water, with aliphatic acid dichloride, either as such or dissolved in 5-10 % w/v of conventional organic solvent, or aromatic acid dichloride, either individually or in any combination with aliphatic acid dichloride, dissolved in 5-10 % w/v of conventional organic solvent, in the presence of 0.25-5.00 % w/v of known phase transfer catalyst at a temperature in the range of 15-35 °C for a minimum period of two hours by conventional method,(ii) subjecting the reaction mixture, as formed in step(i) to separation by conventional method followed by purification of the resulting substance by conventional method using 1-5% vv/w, of moisture absorbing agents and/or 5-20% w/w, of non-solvent and subsequent drying by known method at a temperature between 15-50°C to obtain poly(acyl sulfide) polymer. 2. A process, as claimed in claim 1, wherein the alkali metal sulfide used is selected from sodium sulfide nonahydrate, pottasium sulfide. 3. A process, as claimed in Claims 1 to 2, wherein the aromatic acid dichlorides used is selected from group consisting of terephthaloyl chloride, isophthaloyl chloride, 4,4 -biphenyl dicarboxyloylchloride, 2,6-Naphthalene dicarboxyloylchloride, 1,4-Naphthalene dicarboxyloylchloride, either individually or in any combinations. 4. A process, as claimed in Claims 1 to 3, wherein the aliphatic acid dichlorides used is selected from a group consisting of adipoyl chloride, sebacoyl chloride, dodecane dicarboxyloylchloride, either individually or in any combinations. 5. A process, as claimed in claims 1 to 4, wherein the conventional organic solvent used is selected from group consisting of carbon tetrachloride, cyclohexane, dichloromethane, chloroform, toluene, tetrahydrofuran. 6. A process, as claimed in claims 1 to 5, wherein the phase transfer catalyst used is selected from Tetrabutylammonium bromide, Tetrabutylammoniumhydrogen sulphate, Cetyltrimethylammonium bromide, Cetyltributylphosphonium bromide, dibenzo-18-Crown-6. 7. A process, as claimed in claims 1 to 6, wherein the drying agent used is selected from anhydrous Na2S04, anhydrous MgS04. 8. A process, as claimed in claims 1 to 7, wherein the non-solvent used is selected from methanol, ethanol, petroleum ether, hexane, heptane. 9. A process for the preparation of poly(acyl sulfide) for industrial applications, substantially as herein described with reference to the examples. |
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751-DEL-2002-Claims-(01-10-2010).pdf
751-DEL-2002-Correspondence-Others-(01-10-2010).pdf
751-del-2002-correspondence-others.pdf
751-del-2002-correspondence-po.pdf
751-del-2002-description (complete).pdf
Patent Number | 243898 | |||||||||
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Indian Patent Application Number | 751/DEL/2002 | |||||||||
PG Journal Number | 46/2010 | |||||||||
Publication Date | 12-Nov-2010 | |||||||||
Grant Date | 10-Nov-2010 | |||||||||
Date of Filing | 16-Jul-2002 | |||||||||
Name of Patentee | COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH | |||||||||
Applicant Address | RAFI MARG, NEW DELHI-110001, INDIA | |||||||||
Inventors:
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PCT International Classification Number | C08G 75/00 | |||||||||
PCT International Application Number | N/A | |||||||||
PCT International Filing date | ||||||||||
PCT Conventions:
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