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US 4,540,785 AGranted
Substituted hydroquinones
AssigneeCiba-Geigy Corporation
InventorNorman A. Smith
Life of this patent
Estimating the term…
Abstract
Hydroquinones of the formula ##STR1## wherein X is the residue of a 5- or 6-membered ring, R.sub.1 is hydrogen, alkyl or aryl, R.sub.1,R.sub.3, R.sub.4 and R.sub.5 are hydrogen or alkyl and R.sub.6 is hydrogen or a group of the formula ##STR2## wherein X and R.sub.1 are as defined above, are of use as protected developing agents in photographic silver halide material.
Claims3
A substituted hydroquinone of formula ##STR17## wherein X represents the atoms to complete a benzo, naphtho, pyrido, pyrazo, imidazolo or pyrrolo radical,
- R.sub.1 is hydrogen, alkyl having 1 to 4 carbon atoms, phenyl or naphthyl, these radicals being unsubstituted or substituted by chlorine, bromine, iodine, --COOH, --COOR, --CONHR or --CON(R).sub.2 wherein R is alkyl having 1 to 4 carbon atoms,
- R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each hydrogen or alkyl having 1 to 4 carbon atoms,
- R.sub.6 is hydrogen or a group of the formula ##STR18## wherein R.sub.1 and X have the meanings assigned to them above.
Dependencies are inferred from the claim text.