The Grignard reaction is an organometallic chemical reaction in which an organomagnesium halide (also known as a Grignard reagent) adds to the carbonyl group of an aldehyde or ketone to form an alcohol. The Grignard reaction is one of the most important synthetic methods for forming carbon-carbon bonds.
Being extremely good nucleophiles, Grignard reagents are highly reactive compounds. This means that in the lab we would prepare these freshly in situ just before we carry out our Grignard reaction. It also means we need to keep any trace of moisture out of our reaction. All glassware and solvents must be anhydrous (dry) and the reaction kept in a closed system where water and air cannot get in.
Figure 1: Grignard reagent formation reaction scheme
Once the Grignard reagent has been prepared, we can add a solution of our carbonyl compound (aldehyde or ketone) to the reagent to perform the Grignard addition reaction.
Figure 2: Grignard addition reaction scheme
The final work-up step involves pouring the reaction mixture into a mixture of sulfuric acid and ice to break down the Grignard transition complex and produce our alcohol product.