Flash photolysis of alpha-diazonaphthoquinones in aqueous solution: determination of rates and equilibria for keto-enol tautomerization of 1-indene-3-carboxylic acid

The alpha-diazonaphthoquiones undergo Wolff rearrangement in acidic aqueous solutions, and the resulting ketene yields indene-3-carboxylic acid on hydrolysis. Benzofulvene-8,8-diol is a major reaction intermediate. Spectrophotometric studies of the carboxylic acid reveal that it has two ionization constants at 4.50 plus or minus 0.03 and 15.2 plus or minus 0.2 for OH and CH respectively. The ketene formations rate constant is 2 times 10 to the power of 10 per second under flash photolytic conditions.