Photographic element containing pyrazolone PUG releasing coupler and imaging process employing same

Abstract

The invention provides a photographic element comprising a light-sensitive silver halide emulsion layer having associated therewith an 1-arylpyrazol-5-one coupler bearing a 4-aryloxy coupling-off group containing a group capable of releasing a photographically useful group (PUG) wherein: (1) the 1-arylpyrazol-5-one ring contains a 3-aryl substituent which in turn contains substituents for which the sum of the Hammett's .sigma. constant values is at least 0, provide that two or more such substituents may join to form one or more additional rings; and (2) the 4-aryloxy coupling-off group: (a) contains ring substituents selected so that the sum of the Hammett's sigma constant values for all substituents on the aryloxy ring is at least 0.4 but does not contain a nitro substituent in the ortho position, and: (b) contains in at least one position ortho or para to the oxygen atom bonding the aryloxy group to the pyrazolone ring a substituent comprising a tetrahedral carbon atom bonded to a photographically useful group (PUG) or to another timing group which timing group is in turn bonded to a PUG directly or through a further timing group; provided substituents may join to form one or more additional rings.

Dependencies are inferred from the claim text.