N-trifluoromethyl azomethine prepn from - isocyanide dichlorides and excess sodium fluoride

摘要

N-trifluoromethyl-azomethines of formula CF3N=CR1R2 (where R1 is H, F, Cl and R2 is lower opt. Cl-substd. alkyl or opt. substd. aryl), are prepd. by reacting cpds. of formula R1R2CCl-N=CCl2 with at least the stoichiometric proportion of NaF, per Cl atom to be exchanged, in an aprotic org. solvent. Pref. cpds. prepd. are CF3N=CHF, Cl3C-CF=NCF3, CF3N=CH2 (present as trimer, N,N'-N"-tri-CF3-hexahydrotriazine), Ph-CF=NCF3, Ph-CH=NCF3, ClCH2-CF=N-CF3. Both Cl atoms of isocyanide dichloride function as well as alpha-Cl are substd. by F, followed by isomerisation; dimerisation is suppressed.