Polyfluoroaryl organometallic compounds. Part XV. Synthesis and rearrangement of polyhalogenoaryl α-diketones

Abstract

Decafluoro- and decachloro-benzil have been obtained by reactions of the corresponding aryl-lithiums with dimethyl oxalate in a process shown to involve the intermediacy of adducts. The unsymmetrical benzils C₆F₅·CO·-CO·C₆H₅ and C₆H₅·CO·CO·C₆Cl₅ have been obtained by sequential additions of different aryl-lithiums to dimethyl or diethyl oxalate. Decafluorobenzil undergoes fast base-catalysed rearrangement to the benzilic acid or ester and it is proposed that the transition-state in the process has considerable benzenide character. Attempts to synthesise perfluorophenanthrene-9,10-quinone. by an analogous route, led only to products of rearrangement.