Ciba-geigy Ag

Patrick D Thomas

Stephen R Postle

Brian R Whitear

William E Long

Terence C Webb

Compounds of the formula ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are hydrogen or alkyl, X represents the atoms to complete an aromatic heterocyclic ring system and Y is hydrogen or has the meaning assigned to X, are readily cleaved in alkaline solutions to release a hydroquinone derivative. The compounds can be incorporated into photographic materials used for activation processing.

Hydroquinone derivatives and their use in photographic materials

Substituted hydroquinone compounds of the formula ##STR1## wherein R.sub.1 to R.sub.4 are hydrogen or alkyl and Z is an aromatic ring or a group of the formula --X--Y--X--, wherein X is an aromatic ring and Y is an electron withdrawing group, are incorporated as developers into photographic materials. These materials are suitable for activation processings.

Compounds of the formula ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are hydrogen or alkyl, X represents the atoms to complete an aromatic heterocyclic ring system and Y is hydrogen or the group ##STR2## where X is defined as above, are readily cleaved in alkaline solutions to release a hydroquinone derivative. The compounds can be incorporated into photographic materials used for activation processing.

Hydroquinone derivatives of pyridinecarboxylic acids

A process for the production of a photographic image which comprises

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Chelmsford, United Kingdom

Patrick D Thomas