Reactive intermediates in the reactions of aryl halides with bases

Abstract

The reaction of a series of 2,6-dimethylaryl halides with strong base has been investigated. Debromination to give polymethylbenzenes has been found to occur in all the systems studied and varying amounts of higher-boiling products, mainly polymethyl-bibenzyls, have also been obtained. Various mechanisms for these new reactions are discussed and the participation of an unusual triplet carbene intermediate is suggested. The related thermal decomposition of sodium o-halophenates has also been investigated. The participation of a similar carbene intermediate in this reaction appears to be unlikely. Possible mechanisms for the formation of diphenylmethanes obtained in the decomposition of sodium pentachlorophenate in methylbenzenes, are discussed.