Substituted phenoxy-3-chloro-malealdehydic acids

Abstract

Tanning (hardening) agents in a colloid layer of gelatin or the like are inactive at ordinary temperatures but are activated at temperatures above 70.degree.C. to rapidly tan the colloid in which they are incorporated. Suggested uses are in thermography and photography. Specific examples describe various gelatin layers containing the heat-activated hardeners. The class of useful tanning agents is described by the formula ##SPC1## Wherein the substituents R and R' are selected from hydrogen and halogen atoms and alkyl, carboxyl, alkoxy, formyl, tertiary amino and sulfo radicals. Some specific new compounds of this class are described.

Dependencies are inferred from the claim text.