GB358510A - Manufacture of derivatives of cellulose and other carbohydrates - Google Patents

Abstract

Relates to the production of hydroxyalkyl ester of cellulose and other carbohydrates of the formula (C6H10O5)x and consists in hydroxyalkylating the carbohydrate under mild conditions so that not more than one hydroxyalkyl group is introduced into the molecule (C6H10O5), and then esterifying the product. The partial hydroxylation may be carried out by the use of alkylene oxides, epichlorhydrin &c. under regulated conditions, e.g. by keeping the temperature below 80 DEG C., avoiding excess of alkylating agent, shortening the time of reaction or by carrying out the reaction under normal or reduced pressure. Partial hydroxyalkylation may also be effected by the action of limited quantities of alkylene halohydrin on alkali cellulose. The hydroxyalkyl ethers contain 1-3 hydroxyalkyl groups for each 3 (C6H10O5) molecules and mostly shows the unaltered structure of the original material. They may be esterified in any known manner; e.g. nitrates may be obtained by treatment with nitric acid alone or mixed with sulphuric acid; and organic acid esters may be obtained by treatment with an acid anhydride and an acid preferably in presence of a catalyst such as sulphuric acid or zinc chloride, or by treatment with an acid chloride in presence of a tertiary base. Cellulose acetates directly soluble in acetone may be obtained which show diminished sensitiveness to water. In examples (1) 100 parts cotton linters and 30 parts ethylene oxide are kneaded together until the ethylene oxide is used up; the hydroxyethyl cellulose, which contains one hydroxyethyl group per molecule (C6H10O5) of cellulose is the esterified for 2-3 hours with 200 parts acetic anhydride, 100 parts butyric acid, 300 parts glacial acetic acid, and 8 parts sulphuric acid, yielding a mixed aceto-butyric ester directly soluble in acetone; (2) 100 parts cotton linters, 60 parts ethylene oxide and 5 parts diethylaniline are stored together for 3-4 hours in a pressure vessel at 40-50 DEG C., and excess of ethylene oxide and diethylaniline is removed by feebly acidified water or an organic solvent; the hydroxyethyl cellulose contains about 1 hydroxyethyl group per 3 molecules of cellulose and is acetylated by treatment in a pressure vessel at 34-45 DEG C. with 250 parts acetic anhydride, 200 parts liquid sulphur dioxide, and 20-30 parts zinc chloride; after about 3 hours the mass is precipitated and worked up in the usual manner, yielding a product soluble in acetone. Reference is made to German Specifications 363,192 and 368,413. The Specification as open to inspection under Sect. 91 (3) (a) includes a further example involving the treatment of cotton linters with ethylene oxide at 50 DEG C. followed by acetylation. This subject-matter does not appear in the Specification as accepted.