The pyrolysis of cellulose and the action of flame‐retardants

Abstract In further work on the vacuum pyrolysis of cotton cellulose, alone or with flame‐retardants, at temperatures usually near 420°, products have been identified and determined. In the tar, laevoglucosan has been determined by an infra‐red absorption method, and by gas‐liquid chromatography of its trimethylsilyl ether; 5‐(hydroxymethyl)furfural and 1,6‐anhydro‐β‐ D ‐glucofuranose have been identified and determined similarly by gas‐liquid chromatography. By thin‐layer chromatography of the 2,4‐dinitrophenylhydrazones, 19 carbonyl compounds have been identified in the products from pure cotton; fewer were found from cotton treated with flame‐retardants. The distribution of boron, nitrogen, phosphorus and chlorine from appropriate flame‐retardants has been determined among the products of pyrolysis of cotton. It is concluded that borax/boric acid, and APO‐THPC, act predominantly in the solid phase; Proban appears to act partly in the vapour phase. Mechanisms of pyrolysis are proposed. In a pure cotton cellulose, 1,2‐anhydroglucoses are regarded as important intermediates.