Method of production of vinylidene fluoride.

摘要

Method comprises: (a) heating a gaseous mixt. of 1-chloro-1,1-difluoro-ethane (1426) and HCl at 200-700 deg.C. i the presence of a catalyst selected from a gas contg. O2, a metallic salt or both, the metal is Al-Ni or Cr and the salt being a nitrate chloride sulphate or fluoride formed. USE/ADVANTAGE - Vinylidene fluoride is used in the prodn. of fluorocarbon polymers which are very stable to atmos. conditions and chemical agents. It has been found that mixts. of 142b and HCl, obtd. from the reaction of methyl chloroform and HF, can be pyrolysed in the vapour stae to give good yields of vinylidine fluoride. Pyrolysis effected in the presence or O2 contg. gas such as air - gives good selectivity. The O2 prolongs the life of the metallic salt catalyst (if used) and good yields of vinyldine fluoride are obtd.. The process is pref. carried out continuously in the co-prods. generally formed are 1,1,1-trifluoro-ethane (143a), 1-chloro-1-fluoro-ethylene (VClF), and 1,1-dichloro-1-fluoroethane (141b) can be recycled.