GB679833A - Improvements in or relating to the production of cellulose - Google Patents

Abstract

Cellulose is obtained from ligno-cellulose material by heating the material with a substantially anhydrous liquid mixture of a chlorinated lower fatty acid (i.e. one containing not more than 4 carbon atoms in the molecule) and an organic diluent which does not react with it. Mono-, di-, or tri-chloracetic acid, or a mono- or di-chlorpropionic acid may be used. The diluent may be chloroform, acetone, a hydrocarbon, particularly an aromatic hydrocarbon containing 8 carbon atoms, a normally liquid nitro- or halogenated aromatic hydrocarbon, a fatty acid containing 2-4 carbon atoms, or a fatty acid ester, e.g. ethyl acetate. A diluent having a boiling-point above 110 DEG C. is preferred. It may be a xylene, ethyl benzene, nitrobenzene, chlorobenzene, acetic acid, propionic acid, ethyl valerate or isovalerate, or ethyl chloracetate. A mixture containing 45-85 per cent by weight of chloracetic acid may be used at 120-150 DEG C. for the treatment of wood. At the end of the treatment the cellulose is freed from the treating liquid, e.g. by washing with an appropriate liquid. It may then be subjected to a treatment with caustic alkali, sodium chlorite, or sodium hypochlorite. Chloracetic acid and diluent may be recovered from the used treating liquid and the first wash liquors by diluting with a large quantity of alcohol or water so as to precipitate the lignin and, after removal of the lignin, reconcentrating, e.g. by a solvent extraction method. Alternatively the reagents may be recovered from the used liquids by a distillation method. The treatment may be applied to spruce, larch, fir, poplar, beech, eucalyptus, and other woods, and to cereal straws and the residues of other annual plants. Specifications 640,490 and 679,832 are referred to.