engleski

Photodehydration in 4-[(hydroxymethyl)naphthyl]phenol derivatives

Quinone methides (QM) are commonly encountered reactive intermediates in chemistry and photochemistry of phenols [1]. One method for the photochemical generation of QMs is by photoelimination of H2O from hydroxymethyl-substituted phenols [2]. The mechanism of the reaction involves excited state intramolecular proton transfer (ESIPT) that is coupled with dehydration. The scope of the photoreaction can be extended to larger chromophoric systems wherein the phenol and the benzyl alcohols are not in proximity, such as in phenyl-phenols [3] or naphthols [4]. However, in these examples, transfer of the proton from the phenol to the distal basic site requires mediation by a protic solvent. Herein we report on the investigation of photodehydration reactions in a series of 4-[(hydroxymethyl)naphthyl]phenols 1-3. The compounds are designed to investigate the optimal substitution pattern of the naphthalene chromophore for the formal transfer of the phenolic OH proton to the benzyl alcohol and dehydration reaction. The photodehydration was investigated by irradiations in CH3OH, wherein photomethanolysis product indicate intermediacy of QMs. In addition, we performed fluorescence and laser flash photolysis study.

ESIPT; quinone methides; photochemistry

nije evidentirano