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. C6F5– 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.