method for the optical bleaching of organic materials with 4,4 '- di substituted stilbenes and method for the preparation of these stilbenes.

摘要

Optical brightening agents of the general formula FORM:1106477/C3/1 wherein A and A1 are identical or different and each represents an aryl or aralkenyl radical or a heterocyclic residue of aromatic character, may be incorporated in polymers or polycondensates. The brighteners may be added to the starting materials, reaction mixtures or intermediate products used in the manufacture of the polymers or polycondensates, or may be added to a melt of the polymer or polycondensate prior to extrusion of the melt to form fibres or rolling of the melt on a calendar to form foils. Examples describe melts containing a brightening agent and (10) chip polyamide (from hexamethylenediamine adipate) and TiO2; (11) polyester granulate (from polyterephthalic acid ethylene glycol ester); (12) polypropylene; and (13) polyvinyl chloride or polyethylene, TiO2, dioctyl phthalate and a stabilizer. Numerous other polymers are mentioned in general terms.ALSO:Optical brightening agents of the general formula FORM:1106477/C4-C5/1 wherein A and A1 are identical or different and each represents an aryl or aralkenyl radical or a heterocylic residue of aromatic character may be admixed with detergents, e.g. soaps, salts of sulphonate washing agents, or non-ionic washing agents.ALSO:The invention comprises compounds of the general formula FORM:1106477/C2/1 wherein A and A1 are identical or different and each represents an aryl or aralkenyl radical or a heterocyclic residue of aromatic nature. The compounds may be prepared (a) by dehydration of arylhydrazines of the general formula FORM:1106477/C2/2 (b) by heating mixtures of sulphur and methylphenyl oxadiazoles of the formula FORM:1106477/C2/3 (c) by dehydrogenating compounds of the formula FORM:1106477/C2/4 or (d) by the action of imidoethers on the corresponding carboxylic acid hydrazides. The starting material of formula FORM:1106477/C2/5 is prepared by reacting benzoic acid mono-hydrazide with stilbene-4,41-dicarboxylic acid dichloride. Stilbene-4,41-dicarboxylic acid dihydrazide is prepared by reacting hyrazine hydrate with stilbene-4,41-dicarboxylic acid diethyl ester, and is then reacted with para-n-octyloxy-benzoyl chloride to give the compound of formula FORM:1106477/C2/6 The compound of formula FORM:1106477/C2/7 is prepared from dibenzyl-4,41-dicarboxylic acid dichloride and benzoic acid monohydrazide, followed by cyclization with thionyl chloride. Stilbene-4,41-dicarboxylic acid diethyl ester is partially hydrolysed with sodium hydroxide to give the compound. FORM:1106477/C2/8 which is reacted with thionyl chloride to give the compound FORM:1106477/C2/9 This compound, on reaction with p-t-butyl-benzoic acid hydrazide, yields the compound of formula FORM:1106477/C2/100 which is then reacted with hydrazine hydrate to give the compound FORM:1106477/C2/111ALSO:Organic fibrous materials may be optically brightened by the application thereto of at least one compound of the general formula FORM:1106477/D1-D2/1 wherein A and A1 are identical or different and each represents an aryl or aralkenyl radical or a heterocyclic residue of aromatic nature. The organic material may be fully synthetic, e.g. polymers and polycondensates, semi-synthetic, e.g. those derived from cellulose and casein, or natural materials of animal or vegetable origin.