Multiple substituent effects on ¹³C chemical shifts in phenylstyryl ketones: Applicability of interactive free energy relationship

Abstract

¹³C chemical shifts for 23 mono- and di-substituted phenyl styryl ketones have been determined. The shieldings and deshieldings are compared with previous results for other aromatic derivatives. Correlations of the ¹³C chemical shifts of

vinyl carbons with Hammett σ parameters has been determined to provide a consistent picture of electronic effects transmitted through the carbon framework of the compounds studied. Slopes obtained from such Hammett's plots are termed as ρ, and using these 'ρ' values applicability of interactive free energy relationship to chemical shift values has been tested. The cross- interaction constants q_x and q_y values for C-α are found to be - 1.02 and -1.20 and for C-β are -1.46 and -1.19.