Answer :
Final answer:
The mechanism for the addition of Grignard reagents to carbonyls involves the formation of an acid-base complex between the Grignard reagent and the carbonyl oxygen.
Explanation:
The process by which Grignard reagents are added to carbonyls begins with the carbonyl oxygen and *MgX (the Grignard reagent) forming an acid-base complex. This complex is formed because the *MgX acts as a Lewis acid, accepting a lone pair of electrons from the carbonyl oxygen.
The positive charge on the oxygen increases the partial positive charge on the carbonyl carbon, making it susceptible to nucleophilic attack. The carbanion nucleophile from the Grignard reagent adds to the electrophilic carbon of the acid-base complex, forming a C-C bond. The electrons from the C=O bond are pushed toward the oxygen, forming a tetrahedral magnesium alkoxide intermediate. This intermediate is then converted to an alcohol through the addition of an acidic aqueous solution.
