Patent GB-668200-A (GB)
Title: Manufacture and application of optical brightening agents
Filed: 1949-07-28
Abstract: Optical brightening agents are prepared by reducing a 1,4-di-(nitrostyryl)-benzene disulphonic acid aryl ester of the formula <FORM:0668200/IV (b)/1> wherein X1 stands for a nitro group and X2 for a sulphonic acid aryl ester group, or vice versa, to convert the p  nitro groups into amino groups, hydrolysing the aryl ester groups, and then acylating the amino groups to introduce an acyl radical of a fatty acid, a substituted fatty acid, an araliphatic carboxylic acid, a carbamic acid or a carbonic acid monoester. The hydrolysis of the aryl ester groups is preferably carried out with alkaline hydroxides in alcoholic solution, e.g. methyl or ethyl alcohol or ethylene glycol, and the acylation is suitably effected in aqueous solution with the addition of acid binding agents where necessary.  Inert solvents such as benzene, toluene, xylenes or trichloroethylene may also be present in a two-phase system.  In examples: (1) 41,411-diacetylamino - 1,4 - distyrylbenzene - 21, 211-disulphonic acid is made by reducing 41,411-dinitro - 1,4 - distyrylbenzene - 21,211 - disulphonic acid phenyl ester with iron filings and acetic acid, hydrolysing with aqueous alcoholic caustic soda, and acetylating with acetic anhydride in the presence of soda ash; (2) 41,411 - di - (ethylcarbamatoamino) - 1,4 - distyrylbenzene-21,211-disulphonic acid is made by treating the diamino-disulphonic acid of (1) with ethyl chloroformate; (3) 41,411-di-(phenoxy - acetylamino) - 1,4 - distyrylbenzene-21,211-disulphonic acid is made by reacting the diamino-disulphonic acid of (1) with phenoxyacetyl chloride; (4) 21,211-diacetylamino-1,4-distyrylbenzene - 41,411 - disulphonic acid is made by reducing 21,211-dinitro-1,4-distyrylbenzene-41, 411-disulphonic acid by the method used in (1), hydrolysing with caustic soda in aqueous ethylene glycol, and acetylating with acetic anhydride; and (5) 21,211-carbamido-1,4 - distyrylbenzene - 41,411 - disulphonic acid is made by treating the diamino-disulphonic acid obtained in (4) with potassium cyanate in aqueous acetic acid. Specification 668,199 is referred to.ALSO:Optical brightening agents prepared by reducing a 1,4-di-(nitrostyryle)-benzene disulphonic acid aryl ester of the formula <FORM:0668200/IV (c)/1> wherein X stands for a nitro group and X2 for a sulphonic acid aryl ester group, or vice versa, to convert the nitro groups into amino groups, hydrolysing the acyl ester groups, and then acylating the amino groups to introduce an aryl radical of a fatty acid, a substituted fatty acid, an araliphatic carboxylic acid, a carbamic acid or a carbonic acid mono-ester, have an affinity for animal or vegetable fibres, regenerated cellulose fibres, casein fibres, super-polyamide fibres and the like, and may be applied by incorporation in washing or rinsing liquors.  In examples: (1) to (5) 41,411-diacetyl - amino - 1,4 - distyrylbenzene - 21,211-disulphonic acid, 41,411 - di - (ethylcarbamatoamino) - 1,4 - distyrylbenzene - 21,211 - disulphonic acid, 41,411 - di - (phenoxy - acetylamino) - 1,4 - distyrylbenzene - 21,211 - disulphonic acid, 21,211 - diacetylamino - 1,4-distyrylbenzene - 41,411 - disulphonic acid, and 21,211 - carbamido - 1,4 - distyrylbenzene - 41,411-disulphonic acid are prepared; (6) regenerated cellulose is treated with an aqueous solution containing the sodium salt of 41,411-diacetylamino - 1,4 - distyrylbenzene - 21,211 - disulphonic acid and sodium sulphate; and (7) woollen yarn is treated with an aqueous solution containing the sodium salt of 21,211-diacetylamino - 1,4 - distyrylbenzene - 41,411-disulphonic acid and formic acid.  Specification 668,199 is referred to.