The spin-delocalization substituent parameter σ ·JJ. 9. Cyclodimerization rates of para-methylsulfinyl and para-methylsulfonyl α,β,β-trifluorostyrenes

Abstract

19F NMR data and rate constants for the thermal cyclodimerization of para-methylsulfinyl α,β,β-trifluorostyrene ( 1) and para-methylsulfonyl α,β,β-trifluorostyrene ( 2) have been measured. On the basis of these data, the σ mb and σ · JJ values for p-MeSO and p-MeSO 2 groups have been evaluated. Three methods for the calculation of the σ · JJ scale yielded the same set of σ · JJ constants.