Which of the following tertiary alcohols CANNOT be prepared by the reaction of an ester with an excess of a single Grignard reagent followed by acidic hydrolysis?

Step-by-step solution

The reaction of an ester ( R-COOR ' ) with an excess of a Grignard reagent ( R '' MgX ) involves two equivalents of the Grignard reagent adding to the carbonyl carbon. The general reaction is: R-COOR ' + 2 R '' MgX H ₃ O ^+ R-C(R '')₂ OH + R ' OH This mechanism requires that the resulting tertiary alcohol must have at least two identical alkyl or aryl groups attached to the carbinol carbon (the R '' groups). Analyzing the given options: 2-methylbutan-2-ol has two methyl groups. 3-phenylpentan-3-ol has two ethyl gro