GB363986A - Improvements in the manufacture of acidylated aromatic amines - Google Patents

Abstract

Diacidyl derivatives of aromatic diamino bases of the benzene or naphthalene series are obtained in a fine state of subdivision suitable for incorporation in cellulose ester spinning solutions by acidylation of the base in dilute solution, suspension or dispersion at under boiling temperature (preferably from 30-80 DEG C.). The concentration should not exceed 10 to 15 per cent; the best results are obtained at 5 per cent or under. It is preferable to employ a solvent in which the diacyl derivative is insoluble. The diamino base may be added to the bulk of the acidylating agent which may be an acid anhydride or halide in the presence or not of a basic organic or inorganic compound incapable of acidylation, e.g. a tertiary organic base. The acidylation may be effected in the presence of wetting agents or compounds adapted to inhibit aggregation, e.g. cellulose acetate or other base suitable for the manufacture of artificial filaments or in the presence of a cellulose ester in an esterification mixture before or after ripening. In this manner the diacyl compound is obtained in a finely divided state in the cellulose ester solution. Such dispersions are suitable for subsequent solution in acetone &c. for the preparation of spinning solutions for spinning artificial filaments &c. as described in Specification 346,678. The acidylation may also take place in any other suitable solution of the cellulose ester, e.g. in the spinning solution itself. The diamino base, e.g. benzidine, tolidine, phenylene diamines, &c., used as starting materials may be purified by boiling a solution thereof with animal charcoal, active carbon, silica gel, &c., or by distillation. In examples, (1) purified benzidine is dissolved in xylene (20-50 parts), acetic anhydride added with vigorous stirring and the precipitated benzidine filtered quickly; after washing with xylene and then acetone the product is ready for incorporation in the spinning solution, or it may be broken down with further milling; (2) a solution of benzidine in xylene is added to a warm solution of acetic anhydride in xylene; (3) benzidine purified by means of sodium sulphite and Norit XXX.EF (active carbon) is treated with benzoyl chloride in methylated spirit solution in presence of chalk and Sapamine CH and the washed product stirred with dilute hydrochloric acid and water; the remaining water is displaced by acetone, the acetone paste is milled and the whole incorporated in the spinning solution; (4) benzidine purified by distillation is treated with benzoyl chloride in purified pyridine solution; (5) cellulose is acetylated in known manner with acetic anhydride in presence of acetic and sulphuric acids, the mix is treated with a solution of benzidine in glacial acetic acid and the suspension of diacetylbenzidine in cellulose acetate precipitated after the ripening process by addition of water of dilute acetic acid. Phthalyl and oxalyl derivatives are referred to. Specification 364,040 is disclaimed. According to the Second Provisional Specification acetic acid may be used as acidylating agent.