Title of Invention	"AN IMPROVED PROCESS FOR THE PREPARATION OF N-SUBSTITUTED ACRYLAMIDES"
Abstract	The present invention relates to a process for the preparation of n- substituted acrylamides. The process employs mild reaction conditions such as reaction at room temp, and atmospheric pressure which obviates the tedious work procedures used in the conventional processes.

Full Text

This invention relates to a process for the preparation of N-substituted acrylamides. More particularly it relates to a process for the preparation of N-alkylacrylamides of the formula CH2=CH-CONH-(CH2)„-CH3 and N-acylacrylamides of the formula CH2=CH-CONH-CO-(CH2)„-CH3, wherein, n is an integer of from 0 to 21 by Friedel - Craft's alkylation and acylation of acrylamide respectively, in the presence of a Lewis acid catalyst. Copolymers of N-alkylacrylamides with various other monomers are finding diverse applications as follows: 1) Poly (ß napthyl 6 acrylamidocaproate -co - acrylic acid) as plant growth regulator (C. J. Boundreaux, W. C. Bunyard and C. L. Mccormick, J. Controlled Rel 40, 223 (1996). 2) Poly (N-dodecylacrylamide -co - N-methyl 4vinyl pyridinium Na) as salt resistant viscosity builder (D. Christine, B. Alain and L. Pierre, Ma^romol. Symp. 102, 233 (1995), D. Christine, B. Alain, B. Fransis and V. M. Laure, Polymer 36, 2095 (1995). 3) Poly (N-stearoyl acrylamide -co - 2(3-acrylamidopropyl)dimethyl aminoethyl isopropyl phosphate) as phosphatidylcholine analogous material (W. Yenfeng, C. Tianming, K. Masaya and N. Tadao, J. Polym. Sci. Chem. Edn. 34, 449 (1996). 4) Poly (N-tert - octylacrylamide -co - N-alkylacrylamide) as thickner in cosmetics (J. Mondet and B. Lion Eur. Pat. Appl. EP 494,022). 5) 5) • Poly (N-octylacrylamide - co - 3 acrylamido- 3 methyl butanoate Na) for oil recovery (A. Kitagawa and T. Koichi, Jpn. Kokai Tokkyo Koho JP 07,188,347) and so on. Crosslinked hydrogels based on N-alkylacrylamides also find various applications such as thermosensetive polymeric drug carriers (C. L. Mccormick and J. C. Brent, Polym. Mater. Sci. Eng. 55, 366 (1986), M. Akashi, A. Kishida, S. Sakuma and H. Kikuchi, PCT Int. Appl. WO 9730730, H. Yu and D. W. Grainger, Polym. Prepr. 34, 820 (1993), materials for hard contact lenses (S. Q. Zhou, L. Xiugao and Y. Wang PCT Intl.Appl. WO 9735,896), concentration of aqueous protein solutions (J. Manrong, Z. Guiying, W. Changfa, L. Peiyi and H. Wei, Gaofenzi Xubao 3, 321 (1995), stationary phases for HPLC ((N. Shoji, I. Hirotaka and H. Chuichi, Polymer J. (Tokkyoj 25, 609 (1993)) etc. In order to meet these growing demands of N-alkylacrylamides, various methods for their synthesis have been developed. These methods can broadly be classified into three types viz. 1) Reaction of acryloyl chloride with alkyl amine , 2) Pyrolysis or thermal decomposition of carboxylic acid amides, and 3) Reaction of olefins with nitriles. Theabove mentioned processes are described in brief hereinbelow: Methods of type 1) Reaction of acryloyl chloride with alkylamine In this method N-alkylacrylamides are synthesized by reacting acryloyl chloride with alkyl amines in the presence of acid quencher i.e. triethyl amine at 0°C. (C. G. Overberger, C. Frazier and J. Mandehman, J. Am. Chem. Soc. 75, 3326 (1953), J. Lai and G. S. Trick, J. Polym. Sci. A2, 4559 (1964), E.F.Jr. Jordan. G. R. Riser and B. Artymyshyn, J. Appl. Polym. Sci. 13, 1777 (1969), K. J. Shea, G. J. Stoddard, D. M. Shavelle, F. Wakui and R. M. Chaote, Macromolecuks 23, 4497 (1990). Methods of type 2) Thermal decomposition of carboxylic acid amides A number of patents which are based on this technique have been filed. A Japanese patent No. Jpn. Kokai Tokkyo Koho JP 07,145122, discloses the synthesis of N,N diethylacrylamide.as follows. Methyl acrylate was reacted with diethylamine to give Michael addition product methyl ß N,N diethylaminopropionate. This was treated with sodium methoxide for 46 hrs and then with phosphoric acid for 1 hr at 50°C to give N,N diethyl ß diethylaminopropionic acid amide which was then thermally decomposed at 180°C and 100 torr pressure for 4 hrs to give N,N diethylacrylamide (K. Motomasu, I. Seiichi and I. Massasane, Jpn. Kokai Tokkyo Koho JP 07,145 122). Similar process for the synthesis of N,N dialkyl acryl and methacrylamides has been reported wherein, thermal decomposition of carboxylic acid amide was carried out in the presence of H2S04 at 195°C (T. Maruyama, 0. Kido, I. Okidaka and R. Hiraoka, Jpn. Kokai Tokkyo Koho JP 04,208 258).. N- alkylacrylamides have also been synthesized by amidation of bicyclic carboxylic acids followed by the thermal decomposition of the carboxamide. Thus N,N dimethylacrylamide was synthesized by reacting dimethylamine with bicyclo [2.2.1] hept-2-ene-2-carboxylic acid in autoclave to give N,N dimethyl bicyclo [2.2.1] hept-2-ene-2-carboxamide, followed by its thermal decomposition at 200°C in vacuo (A. Ohshima and K. Tsubashima, Jpn. Tokkyo Koho 7909 170, A. Oshima, K. Tsubashima and N. Takahashi, Ger. Offen. 2,217,623). The use of pyrolysis for preparation of N-alkylacrylamides has also been reported. In this, N(l,l dimethyl l-3-oxybutyl)-3 methoxy propionamide was hydrogenated in the presence of dimethylamine, p-tdluenesulfonic acid and Pt catalyst to give N(l,l dimethyl - 3 dimethyl aminobutyl) 3 methoxy propionamide. This was heated with NaOH at 80 to 90°C for 3 hrs to give N( 1,1 dimethyl -3 dimethylaminobutyl) acrylamide (D. I. Hoke, U.S. 3,943,114). Methods of type 3) Reaction of olefins with nitriles N-alkylacrylamides have also been synthesized by reacting acrylonitrile with various olefins. A Japenese patent No. Japan Kokai 7391011 discloses the synthesis of N-tert- octylacrylamide by reacting acrylonitrile with 2,4,4 trimethyl 1-pentene at 40°C for 3 hrs using 65 % H2S04 as solvent (T. Takada, Y. Kawakatsu, T. Mihamisawa and K. Hara, Japan Kokai 7391011). Similarly, acrylonitrile has been reacted with dimethylamine at 200°C in the presence of Lewis acid ZnCl2 to give N,N dimethylacrylamide (Asahi Chemical Ind. Co. Ltd. Fr. 2,046 122). N-alkylacrylamide has also been synthesized by oxidative carbonylation. In this, PdCl2, CuCl2, CuCl and propylamine in 1 : 10: 10: 120 ratio were treated with methane, carbon monoxide and oxygen to give N-propylacrylamide (G. Biale U.S. 3,523,971). Amongst the above sighted processes for preparation of alkylacrylamides, methods of the type 1) cannot be used to synthesize N-acylacrylamides, monomers, that are gaining increasing importance. Besides, it is also not attractive for large scale productions since it uses acryloyl chloride which is an expensive and hazardous reagent. t Other processes sighted for the preparation of alkylacrylamides i.e. methods of type 2) and 3) suffer from the drawbacks of harsh reaction conditions such as high temperatures, high vacuum and tedious work up procedures. Also in most of the cases N-alkylacrylamide with small alkyl chain length were synthesized. It is therefore an object of the present invention to provide process for the preparation of N-substituted acrylamides. Another object of the present invention is to provide a process with mild reaction conditions such as reaction at room temperature and atmospheric (normal) pressure which will obviate tedious work up procedures used in the conventional processes. It is also an object of the present invention that such a process be applicable for the preparation of N-substituted acrylamides. with long alkyl chain length. Friedel - Craft's alkylation is an effective and convenient method which is widely used to synthesize linear alkyl benzenes (LABs). Despite this its use. in the synthesis of N-alkylacrylamides has not been reported yet. It has now been found that N-alkylacrylamides and N-acylacrylamides can be produced in high yields by alkylation and acylation of acrylamide respectively, in the high yields by alkylation and acylation of acrylamide respectively, in the presence of a Lewis acid catalyst in suitable solvent at room temperature and atmospheric pressure. An improved process for the preparation of N-substituted acrylamides which comprises reacting acrylamide with alkyl /acyl chloride in the presence of a Lewis acid catalyst in an organic solvent at a temperature ranging between 20°C to 50°C for a period ranging between lhour to 24hours, terminating the reaction and cooling to ambient temperature, pouring the mixture in a non solvent to obtain the precipitated product. In one of the embodiment of the present invention acrylamide may be selected from compounds of the formula CH2=CR-CONH2, wherein, R is hydrogen or methyl. In another embodiment alkyl chloride may be selected from compounds of the formula CH3-(CH2)n-Cl, wherein, n is an integer from 0 to 21 and the alkyl chloride may be prepared by treating corresponding alcohol with thionyl chloride. In yet another embodiment acyl chloride used may be such as compounds of the formula CH3-(CH2)n-COCl, wherein, n is an integer from 0 to 16 and the acyl chloride may be prepared by treating corresponding acid with thionyl chloride. In still another embodiment Lewis acid catalyst used may be metal chlorides such as aluminium chloride, zinc chloride, nickel chloride. In an another embodiment the solvent used may be such as acetonitrile, tetrahydrofuran, acetone, nitrobenzene, dioxane. In an another embodiment the non^solvent used may be such as water, hexane, diethyl ether. In a feature of the present invention, the process is typically carried out under mild conditions. Stoichiometric amounts of acrylamide and alkyl chloride or acyl chloride are dissolved in a suitable solvent and the stoichiometric amount of a Lewis acid catalyst is added and the reaction mixture is stirred at room temperature for 5 to 10 minutes. This is followed by vigorous evolution of hydrogen chloride gas formed due to N-alkylation or N-acylation of acrylamide. Reaction is exothermic which increases the temperature of reaction mixture from room temperature to 40 to 50°C. After the evolution of hydrogen chloride ceases, the reaction mixture is cooled down to room temperature and poured into another solvent which is a nonsolvent for the product i.e. N-substituted acrylamide Precipitated N-substituted acrylamide is then isolated. The ranges and limitations provided in the instant specification and claims are those which are believed to particularly point out and distinctly claim the present invention. It is however understood that other ranges and limitations which perform substantially the same function in the same or substantially the same manner to obtain the same or substantially the same results are intended to be within the scope of the instant invention as defined by the instant specification and claims. The process of the instant invention will be further described by the following embodiments which are provided for illustration and are not to be construed as limiting the invention. EXAMPLE 1 Preparation of of N-cetylacrylamide In a 250 ml capacity conical flask 13 g cetyl chloride (0.05 M), 3.5 g acrylamide (0.05 M) and 50 ml acetone were placed to obtain a clear solution. The solution was stirred with a magnetic needle at room temperature. 6.5 g anhydrous aluminium chloride (0.05 M) was added and the reaction mixture was stirred at room temperature. After 5 to 10 minutes of stirring, vigorous evolution of hydrogen chloride took place which ceased after about 5 minutes. Temperature of the reaction mixture raised to 40 to 50°C. It was then cooled to room temperature and poured into 500 ml cold water. White product precipitated. The product was isolated and purified by reprecipitation from acetone into cold water. Yield 65 %. EXAMPLE 2 Synthesis of N-behenylacrylamide In a 250 ml capacity conical flask 8.63 g behenyl chloride (0.025 M), 1.75 g acrylamide (0.025 M) and 50 ml acetone were placed to obtain a clear solution. The solution was stirred with a magnetic needle at room temperature. 3.25 g anhydrous aluminium chloride (0.025 M) was added and the reaction mixture was stirred at room temperature. After 5 to 10 minutes of stirring vigorous evolution of hydrogen chloride took place which ceased after about 5 minutes. The product was isolated following the procedure described for synthesis of N-cetylacrylamide. Yield 83%. EXAMPLE 3 Synthesis of N-dodecanoylacrylamide In a 250 ml capacity conical flask 10.9 g dodecanoyl chloride (0.05 M), 3.5 g acrylamide (0.05 M) and 50 ml acetone were placed to obtain a clear solution. The solution was stirred with a magnetic needle at room temperature. 6.5 g anhydrous aluminium chloride (0.05 M) was added and the reaction mixture was stirred at room temperature. After 5 to 10 minutes of stirring, vigorous evolution of hydrogen chloride took place which ceased after about 5 minutes. The product was isolated following the procedure described for synthesis of N-cetylacrylamide. Yield 50%. EXAMPLE 4 Synthesis of N-stearoylacrylamide In a 250 ml capacity conical flask 15.1 g stearoyl chloride (0.05 M), 3.5 g acrylamide (0.05 M) and 50 ml acetone were placed to obtain a clear r solution. The solution was stirred with a magnetic needle at room temperature. 6.5 g anhydrous aluminium chloride (0.05 M) was added and the reaction mixture was stirred at room temperature. After 5 to 10 minutes of stirring yigorous evolution of hydrogen chloride took place which ceased after about 5 minutes. The product was isolated following the procedure described for synthesis of N-cetylacrylamide. Yield 80 %. The main advantages of the present invention are: 1. The process of the present invention is applicable for the synthesis of N-acylacrylamides as well as N-alkylacrylamides unlike other processes reported in the literature. 2. The reaction conditions are very mild and the time required for reactions to complete is very short in comparison to other processes reported in the literature. 3. The process of the present invention is applicable for the synthesis of N-alkyl/N-acyl acrylamides of small as well as long alkyl/acyl chain unlike the other processes reported in the literature for synthesis of N-alkyl/N-acyl acrylamides with small alkyl chain lengths. WE CLAIM: 1. An improved process for the preparation of N-substituted acrylamides which comprises reacting acrylamide with alkyl /acyl chloride in the presence of a Lewis acid catalyst in an organic solvent at a temperature ranging between 20°C to 50°C for a period ranging between lhour to 24hours, terminating the reaction and cooling to ambient temperature, pouring the mixture in a non solvent to obtain the precipitated product. 2. A process as claimed in claim 1, wherein the acrylamide is selected from compounds of the formula CH2=CR-CONH2, wherein, R is hydrogen or methyl. 3. A process as claimed in claim 1, wherein alkyl chloride is selected from compounds of the formula CH3-(CH2)n-Cl, wherein, n is an integer from 0 to 21 and the alkyl chloride is prepared by treating corresponding alcohol with thionyl chloride. 4. A process as claimed in claim 1, wherein acyl chloride used is from compounds of the formula CH3-(CH2)n-COCl wherein, n is an integer from 0 to 21 and the acyl chloride is prepared by treating corresponding acid with thionyl chloride. 5. A process as claimed in claim 1, wherein Lewis acid catalyst used is from metal chlorides such as aluminum chloride, zinc chloride, nickel chloride. 6. A process as claimed in claim 1, wherein the solvent used is selected from aceto nitrile, tetrahydrofuran, acetone, nitrobenzene, dioxane. 7. An improved process for the preparation of N-substituted acrylamides as substantially described herein before with reference to examples.

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2515-del-1998-abstract.pdf

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2515-del-1998-correspondence-others.pdf

2515-del-1998-correspondence-po.pdf

2515-del-1998-description (complete).pdf

2515-del-1998-form-1.pdf

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2515-del-1998-form-2.pdf

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2515-del-1998-petition-138.pdf