GB757806A - Improvements in protein derivatives - Google Patents

Abstract

Protein derivatives are prepared by reacting a colloidal solution of a protein under alkaline conditions and at elevated temperature with an organic carboxylic or sulphonic acid ester, in which the -COO- or -SO3- group is directly joined to at least one aromatic ring containing an electronegative group in the o- or p-position, or with a carboxylic acid ester of an a :b - or b :g -olefinically unsaturated alcohol. The specified proteins include gelatin, casein, soybean protein and blood albumin. Suitable esters include esters of phenols containing electronegative groups ortho or para to the phenolic oxygen therein such as the formate, acetate, benzoate or benzene sulphonate of a suitable nitro- or chlorophenol; alkyl, aryl or aralky esters of aromatic acids having an o- or p-electronegative group in the acid radical such as ethyl chlorobenzoate, ethyl nitrobenzoate, alkylhydroxynaphthoate and phenyl salicylate; and such unsaturated alcohol esters as isopropenyl acetate, vinyl acetate, crotonyl acetate and styryl acetate. The reaction is preferably carried out with an aqueous dispersion of the protein at a pH of 8 to 12. The protein may be dispersed in water alone or in a water-solvent mixture, e.g. water-acetone, water-formamide or water-dioxane. The protein may also be used in a non-aqueous solvent such as formamide. A temperature of 30-70 DEG C. is used. The reaction product is neutralized with acid and then set or coagulated and washed. The products, especially those prepared from gelatin, are useful for dispersing and peptizing silver halides in photography (see Group XX). In examples (1) an acetone solution of phenyl 1-hydroxy-2-naphthoate is reacted with an aqueous solution of casein, the temperature and pH being maintained at 60 DEG C. and 10 respectively; (2)-(7) aqueous dispersions of gelatin are similarly reacted with o- or p-nitrophenyl acetate, isopropenyl acetate, methyl o-chlorobenzoate, p-nitrophenyl benzoate and phenyl salicylate. Specification 649,548 is referred to.