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The Action of Light on Jute
Author(s) -
CALLOW H. J.,
SPEAKMAN J. B.
Publication year - 1949
Publication title -
journal of the society of dyers and colourists
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.297
H-Index - 49
eISSN - 1478-4408
pISSN - 0037-9859
DOI - 10.1111/j.1478-4408.1949.tb02557.x
Subject(s) - chemistry , acetic anhydride , diazomethane , sodium hypochlorite , aqueous solution , acetic acid , hydrogen peroxide , acetylation , lignin , cellulose , peroxide , nuclear chemistry , peracetic acid , organic chemistry , biochemistry , catalysis , gene
When jute is exposed to light and air, all the main components undergo degradation. An aqueous extract of the exposed material contains reducing substances, which may be aldehydes of low molecular weight derived from the cellulose by main chain fission, because the copper number of jute is increased by exposure. In addition, the aqueous extract is more acid than that from unexposed jute. Part of the acid seems to come from degraded polyuronides, and the remainder from the lignin, which loses methoxyl groups during irradiation. Their loss may lead to the formation of o –diphenols and, ultimately, o –quinones. These seem to be the main cause of the discolouration. which jute suffers during exposure to light and air. in the light of these observations, it seemed probable that discolouration would be prevented by methylation or acetylation. Jute is bleached by treatment with diazomethane, but subsequent discolouration during exposure, though minimiaod, is not entirely prevented. Botter results were obtained hy first bleaching jute with sodium hypochlorite and hydrogen peroxide, and then acetylating with a mixture of acetic anhydride, xylene, and sulphanilic acid at the boil. Acetylation for 3 tir. gives a product which bleaches during irradiation, but some discolouration takes place during acetylation. When, however. the jute is treated for only 1 hr., the primary discolouration is minimised, and tho degree of acetylation is such that neither discolouration nor bleaching takes place during exposure. The bleaching of highly aeetylated jute during irradiation is favoured by the presence of oxygen and water. Acetyl groups are lost during exposure, and it seems probable that bleaching is caused by the formation of acetyl peroxide, which was shown to be capable of bleaching aeetylated jute.