Answer :
A Grignard reagent reacts with ketones or esters to form alcohols through a nucleophilic attack, and it is formed by the reaction of an alkyl halide with magnesium metal, showing oxidation and reduction states during its synthesis. Grignard reagents are generally stabilized in an ether solvent and exhibit a covalent character.
The reaction of a Grignard reagent with a ketone or ester results in the formation of an alcohol. The mechanistic steps involve the nucleophilic attack by the carbon anion of the Grignard reagent on the electrophilic carbonyl carbon of the ketone or ester, followed by the collapse of the tetrahedral intermediate that reforms the carbonyl, leading to the expulsion of the leaving group.
In the case of esters, this process occurs twice, resulting in a tertiary alcohol. The formation of the Grignard reagent itself is an example of an oxidation-reduction reaction. During its preparation, the alkyl halide is reduced while the magnesium metal is oxidized.
Grignard reagents exist in solution as complex equilibria between the organic magnesium halide and dialkylmagnesium. These organomagnesium compounds are prepared by reacting an alkyl halide with magnesium in the presence of an ether solvent, such as diethyl ether or tetrahydrofuran (THF), which stabilizes the reactive species.
Despite their ionic appearance, Grignard reagents have significant covalent character due to the polarization of the carbon-magnesium bond, where the carbon has a partial negative charge and the magnesium has a partial positive charge.
