Acta Phys. -Chim. Sin. ›› 1994, Vol. 10 ›› Issue (05): 434-437.doi: 10.3866/PKU.WHXB19940512

• ARTICLE • Previous Articles     Next Articles

Theoretical Studies on the Elimination Reaction of Alkyl Fluorides-1

Li Qing-Ming, Fang De-Cai, Fu Xiao-Yuan   

  1. Chemistry Department, Beijing Normal University, Beijing 100875
  • Received:1993-01-12 Revised:1993-05-28 Published:1994-05-15
  • Contact: Fu Xiao-Yuan

Abstract:

At the level of 3-21G basis set, the transition states of the titled reactions have been optimized by using the energy gradient method with GAUSSIAN 80 program.On this basis, a vibrational analysis has been performed with GAUSSIAN 86 program to make the transition states further confirmed.
It has been found that the substitution of -F, -CN, -NH_2 and -CH_3 at α or β carbon leads to the change of the structures of the transition states of the titled reactions. The charge distribution of the transition states shows that all of them are polarized fourmember ring structures.
It is shown that the substitution of -F at α or β carbon leads to a rising of the reaction arrier height and the barrier of the former is higher than that of the later. However, the substitution of -CN at α and β carbons lead to a rising and a lowering of the reaction barrier respectively. As for the -NH_2 and -CH_3 cases, α substitution always increases the barrier height, while β substitution decreases it, and the substitution effect of -NH_2 is stronger than that of -CH_3. These results are in accord with the conclusions derived from experiments.

Key words: Alkyl fluoride, Elimination reaction, Substitution effect, Transition state