Correlation of the Rate of Solvolysis of Neopentyl Fluoroformate and a Consideration of Alkyl Haloformates in Solvolytic Reactions

Abstract

The specific rates of solvolysis of neopentyl fluoroformate (NeopOCOF, 1) have been measured at 45.0 oC in pure and binary solvent mixtures. These results correlated well with the extended Grunwald-Winstein equation in all of the solvents except the four TFE-ethanol binary solvents. Leaving group effects (kF/kCl values) and sensitivity (l and m values) to changes in solvent nucleophilicity and solvent ionizing power are appreciably similar to those observed previously for the solvolyses of primary and secondary alky haloformates. This is consistent with the addition-elimination pathway as rate-determining. The kinetic solvent isotope effects (KSIEs, kMeOH/kMeOD) and activation parameters for the solvolyses of 1 were also determined. The results are compared with those reported earlier for neopentyl chloroformate (NeopOCOCl, 2) and other alkyl haloroformate esters.