| 摘要 |
<p>Benzopinacols represented by the formula: wherein R1 is hydrogen, alkyl or aryl; R2 and R6 independently are selected from the group consisting of hydrogen, halogen or trifluoromethyl; R3 and R5 independently are selected from the group consisting Or hydrogen, halogen and alkyl or, when taken together with R4, represent a tetramethylene group; and R4 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 at which R2 and R6 are attached are substituted, the substituent is fluorine. These and other 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.</p> |
