PRODUCTION OF 2,2',4,4',5,5'-HEXAARYLBIIMIDAZOLE

摘要

PROBLEM TO BE SOLVED: To suppress the formation of by-products and obtain the subject compound useful as a photochromic material or a photoinitiator by using an alkali metal alcoholate as an alkali in a reaction for oxidative coupling of a specified triarylimidazole. SOLUTION: A 2,4,5-triarylimidazole of formula I (R1 to R10 are each a 1-6C lower alcohol or a 1-6C lower alkoxyl or the like) is subjected to an oxidative coupling in the presence of a halogen as an oxidizing agent in an alcohol-based solvent by using an alkali metal alcoholate (e.g. sodium ethylate) as an alkali to obtain a compound of formula II. One or more kinds of solvents selected from <=4C lower aliphatic alcohols are preferably used as the above alcohol-based solvent and the above halogen is preferably bromine. The above alcoholate is used in an amount of preferably 0.8-1.5 equivalents based on the raw material or about an equivalent based on the halogen.