Patent GB-795755-A (GB)
Title: Process for the manufacture of omega aminocarboxylic acid polymers
IPC: C08G69/08
Filed: 1956-05-04
Abstract: Aliphatic dibasic acids containing 6 to 10 carbon atoms are heated at temperatures above their melting points with ammonia to form the corresponding aliphatic dibasic diamides which are heated at a temperature above 200 DEG  C. and preferably under reduced pressure to effect dismutation to the ammonium salts of the corresponding omega-cyano aliphatic acids which are reacted with hydrogen in the presence of a hydrogenation catalyst to form ammonium salts of the corresponding omega-amino aliphatic acids from which may be prepared o -amino carboxylic acid polymers (see Group IV (a)). specified aliphatic dibasic acids are glutaric, adipic, pimelic, suberic, azelaic and sebacic acids.  When adipic acid is the starting material, the ammonium salt of the corresponding omega-amino aliphatic acid may be heated until substantially all of the water and ammonia have been evolved but for a period insufficient to effect polymerization of the epsilon-caprolactam thus obtained.  The diamide is heated in the presence of acidic catalysts containing at least two active hydrogens, e.g. sulphuric acid, phosphoric acid, the dibasic acids specified above, phthalic and terephthalic acids, m-benzene disulphonic acid, sulphonated polystyrene, sulphated bituminous coal and sulphonated phenolformaldehyde resins.  The hydrogenation is preferably effected in the presence of ammonia, many catalysts therefore being specified, examples being palladium deposited on charcoal and "Raney" cobalt and nickel ("Raney" is a Registered Trade Mark) which may be promoted with, for example, triethylamine or platinum chloride.  Example (1) describes the preparation of #x-caprolactam from adipic acid. Another example describes the synthesis of ammonium 7-aminoheptanoate from pimelic acid by the above described sequence of steps, in the production of a polymer of aminoheptanoic acid anhydride.  French Specification 889,942 and German Specifications 805,758 and 806,454 are referred to.ALSO:Omega-amino-carboxylic acid polymers are made by reacting an aliphatic dibasic acid containing 6 to 10 carbon atoms at a temperature above its melting point with ammonia to convert the acid to the corresponding aliphatic dibasic diamide, said diamide being reacted at a temperature above 200 DEG  C. to effect a dismutation of the diamide to an ammonium salt of the corresponding omega-cyanoaliphatic acid which is reacted with hydrogen in the presence of a hydrogenation catalyst to form an ammonium salt of the corresponding omega-aminoaliphatic acid, said acid being heated to a temperature between 200 DEG  and 300 DEG  C. to eliminate water and ammonia and form a polymer of unit composition -NH(CH2)nCO-, where n is 5 to 9. Specified dibasic acids are glutaric, adipic, pimelic, suberic, azelaic and sebacic acids.  The dismutation of the diamide may be effected in the presence of acidic agents containing at least two active hydrogens, e.g. sulphuric acid, phosphoric acid, polyphosphoric acid, the dibasic acids specified above, phthalic and terephthalic acids, m-benzene disulphonic acid, sulphonated polystyrene, sulphated bituminous coal and sulphonated phenol-formaldehyde resins.  The hydrogenation is preferably effected in the presence of ammonia ; many catalysts for the reaction are specified, examples being palladium deposited on charcoal, "Raney" cobalt or nickel ("Raney" is a Registered Trade Mark) and copper chromite.  Specified polymerization catalysts are water, alkali and alkaline earth metal salts, sodium, lithium, sodium hydride, lithium hydride or titanium dioxide.  The examples describe the preparation of polymers from (I) adipic acid and (II) pimelic acid.  French Specification 889,942 and German Specifications 805,758 and 806,454 are referred to.