261760-97-8

The invention discloses a method for synthesizing 4 -halo -1, 1 and 2 -trifluoro -1 -butene. , Polyhaloethane is synthesized by reaction of chlorotrifluoroethylene with halogen, and then polyhalogenated ethane is reacted with ethylene under the action of a catalyst to synthesize polyhalogenated butane, and finally, 4 - halogenated -1, 1 and 2 -trifluoro -1 -butene are dehalogenated under the action of a reducing agent. The method has the characteristics of simple synthesis method, high product purity and low preparation cost. (by machine translation)

(Chemical Equation Presented) Reactions of chlorine (Cl2) with 4-halo-1,1,2-trifluorobut-1-enes (1, 2, or 3) give open-ion intermediates A and E that are in equilibrium. The open-chloronium ions (E) rearrange to a five-membered-ring halonium ion during ionic chlorination of 3 when the number-4 halo-substituent is iodine. Three-membered-ring bromonium and iodonium ions from alkenes 1, 2, or 3 are rather symmetrical and similar in structure. Quantum chemical calculations show that five-membered-ring halonium ion intermediates are 11 to 27 kcal/mol more stable than the three-membered-ring halonium ions or the open-ions A and E. The five-membered-ring intermediates lead to rearranged products. Rearranged products increase as the number-4 halogen (Z) becomes more nucleophilic (Z: Cl Br I). Open chloronium ions from ionic chlorination of terminal fluorovinyl alkenes are compared to the open ions generated by protons to similar alkenes.