Treatment of Grignard reagents with esters

Tertiary alcohols are also formed by treatment of carboxylic esters with Grignard reagents  

Fewer synthetic variations are possible than with ketones because the two groups introduced by the Grignard reagent must be identical, but the method is nevertheless sometimes preferable as esters are often cheaper and more accessible than ketones or aldehydes. Side reactions seldom occur and yields tend to be satisfactory. 

Bachmann and Hetzner191 obtained triphenylmethanol, m.p. 161-162°, in 90% yield by adding ethyl benzoate in dry benzene during 1 h to phenylmagnesium bromide in anhydrous ether, cooled in water, in such a way that the mixture boils gently. After a final 1 hour s heating on a steam-bath the solution is cooled and hydrolysed by ice and sulfuric acid. 

With formic esters, but only with these esters, the reaction can be stopped at the first stage. Hydrolysis of the adducts then leads to aldehydes, e.g.  

Orthoesters react very smoothly with Grignard reagents, yielding ketones  

---