GB287540A - Manufacture of cellulose esters - Google Patents

Abstract

287,540. Fabriek van Chemische Producten. March 24, 1927, [Convention date]. Cellulose carboxylates; preparatory treatment of cellulose.-In the preparation of cellulose formates, acetates, propionates &c., or mixed esters such as cellulose aceto-formate the cellulose is first subjected to a partial formylizing by means of strong formic acid and zinc chloride or other salt having a similar action. The preliminary formylizing may be repeated and the formylizing may be completed in the presence of a catalyst such as hydrochloric acid alone or sulphonyl chloride or phosphorus oxychloride mixed or not with zinc chloride or calcium chloride. In an example, cotton waste (linters) are steeped in concentrated formic acid containing zinc chloride. The formic acid is separated and the partly formylized cellulose is introduced into a mixture of formic acid, hydrochloric acid and zinc chloride at a temperature of -5‹ C.; the product is separated and spun into artificial silk in known manner. To make cellulose acetate or cellulose acetoformate, there is added to the partially formlyized cellulose acetic anhydride or concentrated acetic acid with hydrochloric acid, sulphuric acid or sulphuric anhydride at a low temperature. If pure cellulose acetate is required the reaction is continued with a sufficient quantity of acetic acid and anhydride and for a sufficient time to eliminate the formyl groups completely.