GB861866A - Improvements in or relating to synthetic polymers - Google Patents

Abstract

Linear polyamides of high molecular weight are produced by heating a dicarboxylic acid with an unsymmetrical primary diamine, wherein the two NH2 groups are joined, in the para position, to a phenylene group via different numbers of methylene groups, the total number of CH2 groups being from 3 to 8. In Example 2, a methanolic solution of beta-(p-aminomethylphenyl) ethylamine is added to a methanolic solution of adipic acid, whereupon the adipic acid salt of the diamine is precipitated. The salt is filtered off, washed and dried. The salt is then heated, together with a very small proportion of acetic acid, in p a sealed tube under nitrogen at 220 DEG C. for 3 hours. The pressure is reduced to 1 atmosphere of nitrogen and the heating continued for 3/4 hour at 275 DEG C., and finally for 1/2 hour under vacuum. A white opaque polyamide is obtained, which may be readily spun into cold-drawable fibres. Example 4 describes the production of a polyamide by heating a salt prepared from gamma(p-aminomethylphenyl) propylamine and sebacic acid. In Example 6, the starting-materials are gamma-(p-beta-aminoethylphenyl) propylamine and adipic acid. In Example 8, the starting-materials are delta-(p-beta-aminoethylphenyl)-n-butylamine and sebacic acid. Other dicarboxylic acids which may be used are: beta-methyl adipic acid, glutaric acid, pimelic acid, hexadecamethylene dicarboxylic acid, pphenylene dipropionic acid, and beta-(p-carboxymethylphenyl)-propionic acid. The unsymmetrical diamines are also suitable for conversion into high-molecular polyureas by condensation with di-isocyanates, or into polyurethanes by condensation with glycol bischloroformates. For preparation of the diamines see Group IV (b). Specification 544,310 is referred to.ALSO:Unsymmetrical p - aminoalkyl - phenyl - alkylamines containing 3 to 8 methylene groups, wherein the chain of methylene groups is broken by a para-phenylene group separated from the two -NH2 groups by different numbers of methylene groups, are prepared by the action of sodium azide on the appropriate p-carboxyalkyl-phenyl-alkanoic acid in the presence of concentrated sulphuric acid. In Example 1, sodium azide is added to beta-(p-carboxymethyl-phenyl) propionic acid dissolved in concentrated sulphuric acid. The solution is stirred for 60 hours, then poured into iced-water, and made strongly alkaline with sodium hydroxide solution. The liberated beta-(p-aminomethylphenyl) ethylamine is extracted with ether, the ethereal solution is dried over KOH pellets, and the solvent is removed. Finally, the diamine is distilled under reduced pressure. Example 5 describes the preparation of gamma-(p-beta-aminoethylphenyl) propylamine from gamma-(p-beta-carboxyethylphenyl) butyric acid. The latter is obtained by boiling ethyl-gamma-(p-propionylphenyl) butyrate with sulphur and morpholine under reflux and then submitting the mixture to hydrolysis and acidification. The unsymmetrical diamines are suitable for conversion into linear polyamides, and also into high-molecular polyureas and polyurethanes (see Group IV (a)). Specification 544,310 is referred to.