Answer :
In the context of organic chemistry, an acid workup is often used after a reaction involving a Grignard reagent. The primary purpose of this step is to stabilize and finalize the product.
Grignard reagents are highly reactive organomagnesium compounds used to form carbon-carbon bonds in reactions. These reagents, however, need to be handled carefully due to their reactivity with water and other protic solvents, which can destroy them. More importantly, the reaction products formed from Grignard reagents usually possess an alkoxide ion, which is a deprotonated alcohol.
The specific purpose of an acid workup in a Grignard reaction is to:
(C) To protonate the alcohol.
Here's why:
Reaction Completion: After the Grignard reagent has reacted with a carbonyl compound (like an aldehyde or ketone) to form an alcohol product, the alkoxide ion (the deprotonated form of the alcohol) is not in its final stable form.
Protonation: The acid workup typically involves adding a dilute acid, such as hydrochloric acid (HCl) or sulfuric acid (H2SO4), to the reaction mixture. This protonates the alkoxide ion, converting it into the desired alcohol.
Stabilization: By protonating the alkoxide, you stabilize the alcohol product and prevent any further unwanted side reactions that could happen due to the basic nature of the alkoxide ion.
Product Isolation: This step also helps in the purification and isolation of the alcohol product from the reaction mixture by converting all intermediates or side products into their final, neutral forms, making them easier to separate.
In summary, the acid workup step is a crucial part of completing Grignard reactions smoothly and successfully converting the reaction product into a stable alcohol form.
