Aromatic polyfluoro-compounds. Part XLVII. The reactions of pentafluorophenyl-lithium with halogeno-olefins

Abstract

Pentafluorophenyl-lithium has been treated with a number of halogeno-olefins of the type CXYCFZ (X, Y, Z, being F, Cl, Br or H). When the olefins were CF₂CFCl and CF₂CCl₂ the products isolated were C₆F₅CFCFCl and C₆F₅CFCCl₂ together with derivatives formed by nucleophilic attack of C₆F₅Li on the polyfluoroaryl ring. The orientation of this attack was shown by chemical and spectroscopic methods to be in the 4-position. However, if the olefins were CFClCFCl or CF₂CHCl, chloropentafluorophenylacetylene was formed. When CF₂CFH or CF₂CFBr were the olefins C₆F₅CCC₆F₅ and its further pentafluorophenyl substituted derivatives e.g. C₆F_5– C₆F₄CCC₆F₅ were isolated. A mechanism has been proposed to explain these results. The effects of solvent and lithium halides on the course of the reactions are also described.