Abstract: Benzopinacol compounds can be prepared by an improved process comprising irradiating a diarylketone with UV radiation in a non-polar hydrocarbon solvent mixed with an alcohol. The volume ratio of the non-polar hydrocarbon solvent to alcohol is between 3:1 and 8:1. The benzopinacols are useful, for example, in imaging materials, such as with certain dyes that are reactive with the ketyl radicals that can be released from the benzopinacols upon heating.

Abstract: Benzopinacols represented by the formula: ##STR1## wherein R.sup.1 is hydrogen, alkyl or aryl;R.sup.2 and R.sup.6 independently are selected from the group consisting of hydrogen, halogen or trifluoromethyl;R.sup.3 and R.sup.5 independently, are selected from the group consisting of hydrogen, halogen and alkyl or, when taken together with R.sup.4, represent a tetramethylene group; andR.sup.4 is selected from the group consisting of hydrogen, halogen, alkyl, alkoxy and phenoxy;With the proviso that when both of the ortho positions of the phenyl groups to which R.sup.2 and R.sup.6 are attached are substituted, the substituent is fluorine. These benzopinacol compounds can be prepared by an improved process comprising irradiating a diarylketone with UV radiation in a non-polar hydrocarbon solvent mixed with an alcohol. The volume ratio of the non-polar hydrocarbon solvent to alcohol is between 3:1 and 8:1.

Abstract: A light-sensitive vesicular imaging composition is disclosed comprising a vesiculating agent which liberates gas upon exposure to activating radiation, a binder and a diol speed-increasing agent. The composition is coated as a thin film. Imagewise irradiation of the element causes gas to be released in the exposed areas. The composition, comprising gas entrapped in a thermoplastic matrix, can be heated to produce a visible record.

Abstract: A heat bleachable layer comprising a benzopinacol and a reducible dye or dye precursor is useful in an imaging element. The heat bleachable layer can be, for instance, an antihalation layer of a photographic element, such as a photothermographic element.