THE SPIN-DELOCALIZATION SUBSTITUENT PARAMETER SIGMA(.)(JJ) .10. THE SPIN-DELOCALIZING ABILITIES OF THE PARA-TRIFLUOROVINYL AND PARA-ACETOXYGROUPS - SYNTHESIS OF A-TRIFLUOROVINYL-ALPHA,BETA,BETA-TRIFLUOROSTYRENE, PARA-VINYL-ALPHA,BETA,BETA-TRIFLUOROSTYRENE AND PARA-ACETOXY-ALPHA,BETA,BETA-TRIFLUOROSTYRENE

para-Trifluorovinyl alpha,beta,beta-trifluorostyrene (1-CF=CF2), p-ace toxy alpha,beta,beta-trifluorostyrene (1-AcO) and p-vinyl alpha,beta,b eta-trifluorostyrene (1-CH=CH2) have been synthesized. The rate consta nts (k) for the thermal cyclodimerization of 1-CF=CF2 and 1-AcO have b een measured over the temperature range 90-130 degrees C for 1-CP=CF2 and 110-160 degrees C for 1-AcO. The sigma(mb) polar substituent const ants of the p-CF=CF2, p-CH=CH2 and p-AcO groups calculated from the F- 19 NMR chemical shifts are: for p-CF=CF2, 0.40; for p-CH=CH2, 0.03; an d for p-AcO, -0.14, and the sigma(jj) spin-delocalization substituent constants of the p-CF=CF2 and p-AcO groups are 0.86 and 0.35, respecti vely, i.e., the former is a highly effective spin-stabilizer while the latter is moderately effective. Owing to the occurrence of a small am ount of side-reaction, the sigma(jj) value of the pCH=CH2 group could not be accurately measured, but it was very roughly estimated to be in the range of 0.50-0.66.