Effect of Substituents and Amines on the Photo-cleavage of the Ether Bond in ω -Phenoxyacetophenones

Abstract

On the photolysis of ω-phenoxyacetophenone (PAP) in benzene solution containing triethylamine, the substituent effect was investigated.
In the case of PhCOCH2OC6H4-X(X=H, OCH3, Cl), the substituent effect on the conversion of PAP was generally small, except for 2- or 3-Cl substituted PAP. But the yield of phenols was affected by the character or position of X. In the case of Y-C6H4COCH2OPh (Y=H, OCH3, Cl), the Photolysis of PAP was accelerated by the substitution of OCH3 or l, and phenol was produced in a good yield.
Next the effect of added amines was examined. When aliphatic amines (di-n-butylamine, cyclohexylamines) were added, the photolysis of PAP was remarkably accelerated and phenol was obtained in a good yield. But, this accelerating effect on the photolysisof PAP was not observed by the addition of the primary, or secondary aromatic amine (aniline, N-methylaniline). N, N-dimethylaniline promoted exceptionally this photo-reaction, although the phenol formation was in low yield.