Eastman-kodak Company

Andrew William Gibson

Michael W Crawley

Hugh M Williamson

Paul L Stanley

Novel non-diffusible pyrazolo-�1,5-a! benzimidazole color couplers having an alkylene-, oxyalkylene- or arylene- thio coupling-off group, substituted with a carboxylic acid or dialkylamino group, have dye-forming and/or bleach-accelerating properties. The couplers are generally associated with a silver halide emulsion layer coated on a support to form a single color or multi-color photographic element.

Pyrazolo 1,5 a benzimidazole photographic color couplers

The invention provides a pyrazolo�1,5-a!benzimidazole compound of the formula (I) ##STR1## wherein R to R.sup.4 are selected from H, substituted or unsubstituted alkoxy, anilino, aryl, alkyl or amido groups, and X is H or a coupling-off group; characterized in that said compound of Formula I is linked via any of the moieties R to R.sup.4 or X to a compound of the formula (II): ##STR2## wherein W is an electron withdrawing group and L is a linking group. Compounds with the low pKa phenolic substituent provide improved coupling activity when used with a photographic element and improved contrast.

Phenol substituted pyrazolo 1, 5-a benzimidazole couplers

Novel 2-alkoxy-pyrazolo[1,5-a]benzimidazole color couplers form dyes with improved hue characteristics in photographic materials and processes. Such couplers can form magenta dyes upon oxidative coupling.

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Woodhead, United Kingdom

Andrew William Gibson