Kinetics and Mechanism of the Reaction between 4,4'-Aryl- methyIidene-Bis-2-Pyrazoline-5-Ones and Quinonediimines

Paper presented at the 1982 International Congress of Photographic Science, organized by The Royal Photographic Society, 6-10 September, 1982 in Cambridge, England.

Abstract

The second order rate constants of the dye formation from 4,4'-arylmelhylidene-bis-2-pyrazoline-5-ones B with quinone-diimine QDI are determined. From the dependence of the rate constants on the substituents in the arylmethylidene bridge and in the pyrazoline-5-one ring as well as from the dependence on the ionic strength it follows that the leuco dye formation LD is the ratedetermining step of dye formation. The azomethine dye D and the 4-arylmethylidene-2-pyrazoline-5-one S are formed from the leuco dye i.D with the same rate. 4-Arylmethylidene-2-pyrazoline-5-one S hydrolyzes under the coupling conditions in a pseudo first order reaction. The comparatively slow hydrolysis of S limits further dye formation.

Notes

Paper presented at the 1982 International Congress of Photographic Science, organized by The Royal Photographic Society, 6-10 September, 1982 in Cambridge, England.