THEORETICAL STUDIES ON THE ELIMINATION OF HYDROGEN FLUORIDE FROM ALKYL FLUORIDE AND ITS SUBSTITUENT EFFECT

摘要

The reaction mechanism of the alpha, alpha and alpha, beta elimination of hydrogen fluorides from alkyl fluorides has been studied theoretically. For fluoroethane as a reactant, the transition state (TS) optimized at the level of the 6-31G** basis set shows that the alpha, beta elimination proceeds via a four membered-ring TS with a barrier height 64.6 kcal/mol, while the alpha, alpha elimination, via a three-membered ring TS with a 83.7 kcal/mol barrier. Four substituents, CH3, CN, F, and NH2, were used to investigate the substituent effect of elimination by using the 3-21G basis set. The calculated barriers show that NH2-substituted alkyl fluorides favor both the alpha, alpha and alpha, beta elimination and these two reactions would be expected to proceed simultaneously. (C) 1996 John Wiley & Sons, Inc. [References: 8]