Influence of conformation on transmission of electronic effects of substituents. Correlation of infrared carbonyl stretching frequencies of 4-substituted α-naphthyl styryl ketones

Abstract

The s-cis and s-trans carbonyl stretching frequencies of several 4-substituted α-naphthyl styryl ketones have been measured in carbon tetrachloride and chloroform. The carbonyl stretching frequencies correlate very well with σ⁺ constants. The low ρ_cis/ρ_trans ratio obtained for the present system compared with benzylideneacetones and chalcones shows that for effective transmission of the electronic effects of the substituents, the styryl group and the carbonyl group must be coplanar. Comparison of the attenuation factors, π_y and π_R, for different α,β-unsaturated ketones also supports this idea.