1-Substd. 2-acyl 3-pyrazolin-5-ones, prepn. and use as couplers - in photographic silver halide material, avoiding side reactions

摘要

Novel-1-substd. 2-acyl-3-pyrazolin-5-ones (I) have the formula (wherein formula (I) R' is an opt. substd. alkyl or aryl gp. Y is H, alkyl or a gp. which can be eliminated on coupling with the oxidn. prod. of a phenolenediamine coupler, R2 is an opt. substd. alkyl, aryl, anilino or acylamino gp. Z is (1) an acyl gp. derived from an organic carboxylic acid, (2) the gp. (II) (in which A is an alkylene gp.) or (3) an opt. substd. alkoxy- or aryloxy-carbonyl gp). Cpds. (I) are prepd. from a 3-alkyl-, 3-aryl-3-anilino or 3-amino-2-pyrazolin-5-one and an organic carbonyl halide or chloroformic ester, followed by acylation if the 3-amino cpd. is used. Cpd. (I) is used as coloured, colourless or white couplers, in photographic Ag halide material. Cpds. (I) ahve an inactive methylene gp. and are converted to the 2-pyrazolin-5-one couplers in alkaline medium, before or during colour development. The absence of a usual methylene gp. as in con conventional couplers prevents undesirable side-reactions with other constituents of the emulsion during mfr. and storage, which could lead to a redn. in the amt. of coupler available for coupling and in the colour density and also to staining.