Patent GB-804225-A (GB)
Title: Improvements in or relating to aromatic dicarboxylic acids, derivatives thereof, and synthetic linear polymers
Inventor: THOMAS PETER RAYMOND
IPC: C07C59/52
Filed: 1956-01-03
Abstract: The invention comprises synthetic linear polyamides of high molecular weight obtainable by heating an aliphatic diamine containing 4-12 carbon atoms with an acid being b -(p-carboxymethoxy-phenyl)-propionic acid or p-carboxymethoxy-phenylacetic acid wherein the phenyl ring may optionally bear alkyl substituents (see Group IV (b)), said diamine and/or said acid optionally taking the form of a polyamide forming functional derivative thereof, or a salt derived from said diamine and acid, so as to bring about condensation polymerization.  The dibasic acids may also be converted to linear polyesters by condensation with glycols or to polyesteramides by condensation with amino-alcohols.  The expression "polyamides of high molecular weight" signifies that the products are sufficiently viscous to be meltspun into filaments.  Amines mentioned for use as starting materials include hexamethylene, 3-methylhexamethylene, tetramethylene, decamethylene, octamethylene and N : N-dimethylhexamethylene diamines, ethylene bis-(3 - aminopropyl) - ether and 1 : 6 - diamino-6-methylheptane.  The diamines may be used in the form of N-formyl-derivatives and the acids in the form of N-formyl-derivatives and the acids in the form of ethyl esters. Additional compounds which may be present in the polymerization reaction mixture include adipic, sebacic, b  - p - phenylene - dipropionic, g  - (p-carboxymethyl-phenyl)-butyric acids and p-dicarboxymethozybenzene, monoamines or monobasic acids, e.g. acetic acid to prevent undesirable polymerization, e.g. at high temperature during melt spinning.  In examples: a polyamide is obtained by heating under nitrogen in a closed vessel and then in a nitrogen stream the salt obtained by reacting hexamethylene diamine with b -(p-carboxymethoxy-phenyl)-propionic acid in methanol, moistened with acetic acid (2); in a similar process the hexamethylene diamine salt of p-carboxymethoxyphenylacetic acid is employed (5) and the hexamethylenediammonium salts of b -p-(carboxymethyl-phenyl)-propionic acid and b -p-phenylene-dipropionic acid are similarly heated together in the presence of acetic acid to obtain a copolymer.  Specification 627,733 is referred to.ALSO:The invention comprises the dicarboxylic acids b -(p-carboxymethoxy-phenyl) propionic acid and p-carboxy-methoxy-phenyl acetic acid, the phenyl rings optionally bearing alkyl substituents, e.g. as in 1-carboxymethoxy-2:5 - dimethylpheny - 4 - propionic acid, and polyamide-forming functional derivatives of said acids.  Such acids or derivatives are converted to linear polyamides by reaction with aliphatic diamines containing 4-12 carbon atoms or polyamide-forming functional derivatives thereof (see Group IV (a)).  In addition the dibasic acids may be converted to linear polyesters by reaction with glycols or polyesteramides by condensation with amino alcohols.  In examples: b -(p-carboxymethoxy-phenyl) propionic acid is obtained by reacting p-hydroxybenzaldehyde with monochloracetic acid in aqueous sodium hydroxide solution and acidifying to obtain p-formyl-phenoxy-acetic acid, reacting the latter with malonic acid in the presence of pyridine and piperidine and acidifying to obtain p-carbomethoxy-cinnamic acid, esterifying the latter with methanol in the presence of sulphuric acid, reducing the dimethyl ester produced with hydrogen using a palladium-charcoal catalyst in ethanol solution and hydrolysing the product with aqueous ethanolic sodium hydroxide (1); p-carboxy-methoxy-phenyl-acetic acid is obtained by nitrating benzyl cyanide, hydrolysing the p-nitro-benzylcyanide produced and esterifying the product, reducing the ethyl-p-nitrophenyl-acetate with hydrogen in the presence of a platinum-carbon catalyst, hydrolysing the ethyl p-aminophenyl acetate with aqueous ethanolic sodium hydroxide, converting the p-amino-phenylacetic acid produced to p-hydroxyphenyl-acetic acid by diazotization and boiling with dilute sulphuric acid, condensing the product with monochloracetic acid in aqueous sodium hydroxide solution and acidifying the reaction mixture (3) and p-carboxymethoxy-phenyl-acetic acid is obtained by condensing p-hydroxy-acetophenone with monochloracetic acid in boiling aqueous sodium hydroxide, acidifying the reaction mixture, boiling the product in morpholine containing sulphur, boiling the product with aqueous alcoholic sodium hydroxide and acidifying the product (4).  Hexamethylene diamine salts of b -(p-carboxy-methoxy-phenyl) propionic and p-carboxy-methoxyphenylacetic acids are prepared in Examples (2) and (5) as intermediates in the preparation of polyamides. Specification 627,733 is referred to.