Molar Kerr constants and molecular conformations of four lactones

Abstract

The molar Kerr constants (× 10¹²) in carbon tetrachloride solution of four lactones [β-propiolactone (182), γ-butyrolactone (200), γ-valerolactone (178), and phthalide (1077)] are discussed in terms of their conformations and the appropriate value of the longitudinal polarisability of the carbonyl bond in cyclic esters. It is found that acceptable conformations of these molecules are best formulated with 10²³b_L^CO= 0·180 (derived from ethylene carbonate) and not with the value 0·230 drawn from acetone.