GB372122A - Manufacture of mixed esters or ether-esters of polymeric carbohydrates - Google Patents

Abstract

The process of making mixed esters or ether-esters of cellulose or other carbohydrates in which esterification of a cellulose &c. derivative still containing free hydroxyl groups is effected with an acid halide in the absence of an agent that binds hydrogen halide, is carried out in the absence of water and with such precautions as will protect the esterification product from the action of the hydrogen halide formed in the reaction. Thus, the hydrogen halide may be eliminated by working under reduced pressure, or by the passage of a dry indifferent gas such as nitrogen or carbon dioxide through the reaction chamber during the esterification process. Alternatively, the reaction may be carried out in the presence of an indifferent liquid which dissolves only the acid chloride, but not the initial carbohydrate derivative and the product of the esterification. The starting materials may be aliphatic, araliphatic and aromatic ethers, hydroxyethers, esters, ether-esters and mixed esters of cellulose, starch, dextrin and agar-agar; and the acid halides, which may be used in the gaseous phase or in the liquid form with or without a diluent, may be derived from the lower or higher substituted or unsubstituted aliphatic, aromatic or alicyclic carboxylic acids. In examples, hydroxypropyl cellulose is esterified with butyric acid chloride in a vacuum at 60-65 DEG C.; hydrolysed cellulose acetate is esterified with cocoa-fatty acid chloride under reduced pressure at 50-70 DEG C.; fibrous hydroxyethyl cellulose is suspended in a solution of acetyl chloride in petroleum ether, and the mixture allowed to stand at room temperature for several days to effect the desired acetylation. The esterified products may be used for preparing lacquers, films, artificial threads, electric insulating materials, impregnating solutions, safety glass, artificial leather, adhesive substances and moulded articles.