| abstract |
Polymer (I) contains a reaction prod. of cpds. (II) and (III) of the formulae R1R2O=CR3-(COY)n-(Z)s-X (II) and R10- (SH)m (in which Y is -O- or -NR4-. Z is a divalent organic gp. X is H, OH, -O-alkyl, -S-alkyl, -SO-alkyl, -CO-alkyl, COOH, -CONR5R6, -NR5R6, -SO3M, heterocyclyl or -PO3HM. R1 to R4 are H or alkyl. R2 is H, alkoxycarbonyl or COOH. R3 is H, (cyclo)alkyl, ar(alk)yl, heterocyclyl, COOH, alkoxy- carbonyl or acylamino. R5 and R6 are alkyl or together complete a heterocycle. M is H or a cation. n is 0 or 1. s is 0 or 1. m is an integer. R4 can complete a heterocycle with Z and/or X. R10 is an m-valent (cyclo)-aliphatic gp. with min. 2 thioether gps., which can contain heteroatoms in the chain). (I) is used in the prodn. of dispersions contg. finely-divided metal (cpd.), esp. in the prodn. of a photographic Ag halide emulsion by reacting a halide and a Ag salt in the presence of (I). It has an affinity for transition metals, esp. noble metals and their cpds. and hence is useful as a protective colloid, e.g. for dispersions of Co, Ni, Cu, Ru, Rh, Pd, Cd, Os, Ir, Pt, Au and Hg, esp. their sulphides, selenides, sulphoselenides, sulphoarsenites or sulphostannates, e.g.Ag, Cu, Co and (Ag,Hg) sulphide and Cd (sulpho)- selenide. |