GB337366A - Process for the manufacture of cellulose fatty acid esters - Google Patents

Abstract

337,366. Carpmael, A., (I. G. Farbenindustrie Akt.-Ges.). July 25, 1929. Cellulose acetates, aceto-propionates, acetobutyrates, &c.-Fatty acid esters of cellulose are produced by carrying out the esterification in the presence of methylene or ethylene chlorides as solvent instead of free acid. By effecting the reaction at temperatures of 20-60‹ C., degradation of the cellulose is avoided and clear solutions of unusual homogeneity and viscosity are obtained which may be spun directly or may be hydrolyzed, e.g. to give acetone solubility. The primary or secondary esters may be precipitated with aqueous or other liquids. The methylene or ethylene chlorides are recovered from the solutions or the precipitated ester by distillation and are returned to the cycle of manufacture. By the use of methylene or ethylene chloride, the quantity of catalyst may be reduced, e.g., 0.5 per cent of sulphuric acid may be employed. The invention is applicable to acetates, propionates, butyrates and mixed esters. Examples are given of the production of acetates from cotton wool and linters by the use of acetate anhydride, methylene or ethylene chloride, and a small quantity of sulphuric acid or sodium bisulphide ; and of aceto-propionates and aceto-butyrates, using acetic anhydride with propionic or butyric acid. Hydrolysis of the primary acetate is effected by addition of 50 per cent of acetic acid and sulphuric acid or of water and hydrochloric or sulphuric acid to give a acetone-soluble acetates which are precipitated with water, washed and dried. When precipitating by the use of non-aqueous liquids, e.g. benzene, the mixture of liquids is worked up by fractional distillation and acetic acid is obtained in concentrated form.