GB959782A - Photographic silver halide emulsions of increased sensitivity and non-polymeric compounds suitable for increasing their sensitivity - Google Patents

Abstract

Compounds are described having the general formula: [-X1-CH2CH2)mX1-] [-CH2CH2-X2 (-CH2CO.O)d (CH2CH2O)n-R1-R]2 wherein R is hydroxy, alkoxy or carboxylic acyloxy, or, when n and d are O and X2 is sulphur, a carbamyl group, R1 is ethylene or an alkyl substituted ethylene, X1 and X2 are oxygen or sulphur (except that X1 and X2 do not both represent oxygen and do not both, when n is 0, represent sulphur), n is 0, 1 or 2 and d and m are 0 or 1. In one general method of preparation, two mols. of a mercaptan are reacted with 1 mol of 1,2-bis (2-chloroethoxy) ethane in the presence of alkali such as sodium carbonate. In an example, 2-mercapto-ethanol is used as the mercaptan to give 1,14-dihydroxy-6, 9-dioxa-3, 12-dithia-tetra-decane. In an alternative general method, 2 mols. of a halide are reacted with 1 mol. of sodium sulphide. Examples are given of the reactions of ethoxyethoxyethyl bromide or ethoxyethoxyethoxyethyl bromide with sodium sulphide to give 3, 6, 12, 15-tetraoxa -9- thiaheptadecane and 3, 6, 9, 15, 18, 21-hexoxa -12- thiatricosane respectively. Compounds wherein R is a carbamyl group, X2 is S and d and n are 0, may be prepared by reacting methacrylamide with a bismercapto compound. An example of this reaction is given using bis(2-mercaptoethoxy) ethane as the bismercapto compound in the presence of benzyl trimethylammonium hydroxide to give 7,10-dioxa-4, 13-dithia-hexadecane-2, 15-dicarboxamide. In a further general method the compounds where d is 0 are prepared by reacting 2 mols. of a b -halogenethyl ether with a dimercapto compound, in the presence of sodium carbonate or sodium ethoxide. Thus ethoxyethoxyethyl bromide is reacted with bis-mercaptoethyl ether or ethane dithiol to give 3, 6, 12, 18, 21-pentoxa-9, 15-dithiatricosane and 3, 6, 15, 18-tetroxa-9, 12-dithia-eicosane respectively, ethoxyethyl bromide is reacted with 1, 2bis(2-mercaptoethoxy)ethane or bis-mercaptoethyl ether to give 3, 9, 12, 18-tetroxa-6, 15-dithia-eicosane and 3, 9, 15-trioxa-6, 12-dithiaheptadecane respectively, and methoxyethyl bromide is reacted with 1, 2-bis(2-mercaptoethoxy) ethane to give 2, 8, 11, 17-tetroxa-5, 14-dithia-octadecane. Compounds wherein d is 1 and X2 is sulphur are prepared by reacting a halogenoacetoxyether with a dimercapto-ether in the presence of sodium carbonate. In examples of this method, hydroxyethyl bromoacetate, hydroxyethoxyethyl bromoacetate or methoxyethyl bromoacetate is reacted with bis-mercaptoethyl ether to give 1, 17-dihydroxy-3, 9, 15-trioxa-6, 12-dithiaheptadecane-4, 14-dione, 1, 23-dihydroxy-3, 6, 12, 18, 21-pentoxa-9, 15-dithiatricosane-7, 17-dione and 2, 5, 11, 17, 20-pentoxa-8, 14- dithiaheneicosane-6, 16-dione respectively, and hydroxyethyl bromoacetate or methoxyethyl bromoacetate is reacted with 1, 2-bis(2-mercaptoethoxy) ethane to give 1, 20-dihydroxy-3, 9, 12, 18-tetroxa-6, 15-dithia-eicosane-4, 17-dione and 2, 5, 11, 14, 20, 23-hexoxa-8, 17-dithiatetracosane-6, 19-dione respectively. Specifications 235,211, 541,589, 545,448, 627,814, 636,140, 649,660, 660,012, 680,488, 711,485, 736,922, 739,913, 791,219, 800,108, 873,198, 874,080, 904,462, 942,932 and 942,935 are referred to.