The maximum yield of addition product from n-butyllithium and representative aldehydes and ketones is obtained by adding a hexane or ether solution of the carbonyl compound to the lithium reagent at -78°. In most cases under these conditions, products resulting from reduction or condensation of the aldehyde or ketone are insignificant, while enolization gives rise to moderate amounts of the starting carbonyl reagent upon hydrolysis. In the case of nonenolizable aldehydes and ketones, quantitative yields of alcohols are obtained. ierl-Butyllithium reacts similarly to ro-butyllithium, but because of increased amounts of enolization, somewhat lower yields of secondary and tertiary alcohols are obtained.
In addition to magnesium 2-methylbenzophenone ketyl ([Ph(Ph')CO]zMg; Ph' = 2-methylphenyl, Ph = phenyl), the bromomagnesium [BrMgOC(Ph)Ph'], methylmagnesium [CH3MgOC(Ph)Ph'], and 1 -(2-methylphenyl)-l-phenylethoxy magnesium [Ph(Ph')(CH,)COMgOC(Ph)Ph'] ketyls of 2-methylbenzophenone have been prepared in diethyl ether and studied by uv and ESR spectroscopy. The ketyl produced during reaction of 2-methylbenzophenone with excess methylmagnesium bromide has been identified as the bromomagnesium ketyl of 2-methylbenzophenone associated with methylmagnesium bromide. In reactions of methylmagnesium bromide with excess 2-methylbenzophenone, the ketyl produced is the bromomagnesium ketyl of 2-methylbenzophenone associated with the 1,2-addition product [Ph( Ph')(CH3)0MgBr]. ';K.-*' .'K-N;lf KF: , e ' K7 = ketyl The purpose of the present study was to prepare by unequivocal methods all of the ketyls that could possibly result from the reaction of methylmagnesium bromide with 2methylbenzophenone. These ketyls were to be observed and Journal of the American Chemical Society / 97.17 / August 20, 1975 (IO) The extent of reaction was followed by monitoring the decrease in absorbance at 410 nm due to the complex between Grignard reagent and ketone."(1 1) E
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