Phenylmagnesium bromide 2-butanone

Another side reaction, caused by changes in the solvent composition, was studied in 1980 (in the former USSR) and, unfortunately, was also published in rather inaccessible journals [37]. The reactions of phenylmagnesium bromide with the aliphatic ketones, 2-butanone and 3,3-dimethyl-2-butanone (methyl-fcrt-butyl ketone), were studied. Besides the carbonyl addition reaction, leading to a tertiary alcohol, enolization also takes place with this type of ketones. The enolate, on hydrolysis, yields the starting ketone however, before hydrolysis, in the reaction mixture of the Grignard reagent and the ketone, the enolate can react further with the ketone to form a condensation product (Scheme 16). 

The rates /Cenoi/ add " re 7 and 8, respectively, for the reactions of phenylmagnesium bromide with 2-butanone and 3,3-dimethyl-2-butanone, but on the addition of large amounts of triethylamine (150 and 90%, respectively, for the two reactions) these rates were almost doubled from 7 to 16 and from 8 to 14. The general conclusion from this work was that triethylamine did not change the rate of the addition reaction, but doubled the rate of the enolization reaction. Still, the influence of the amine on the rates of reactions were much smaller than for the reactions with 1-hexyne, as listed in Table 7. 

Solution 2-Phenyl-2-butanol has a methyl group, an ethyl group, and a phenyl group (-C6IT5) attached to the alcohol carbon atom. Thus, the possibilities are addition of ethylmagnesium bromide to acetophenone, addition of methylmagnesium bromide to propiophenone, and addition of phenylmagnesium bromide to 2-butanone. 

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