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Multiple Choice

Grignard reaction with formaldehyde followed by acid workup yields what type of product?

Grignard reagents add to carbonyl compounds and the carbon attached to the Grignard becomes part of a new alkyl–carbon bond, with the oxygen ending up as an alkoxide that is then protonated in acidic workup to give an alcohol. When formaldehyde is the carbonyl partner, the Grignard adds to the carbonyl carbon to form R–CH2–O–MgX. After hydrolysis, this alkoxide becomes the primary alcohol, giving R–CH2OH. This is in contrast to reactions with other aldehydes that already have an alkyl substituent on the carbonyl carbon, which would produce secondary alcohols (R–CH(OH)–R). Therefore the product is a primary alcohol after hydrolysis.

Grignard reagents add to carbonyl compounds and the carbon attached to the Grignard becomes part of a new alkyl–carbon bond, with the oxygen ending up as an alkoxide that is then protonated in acidic workup to give an alcohol. When formaldehyde is the carbonyl partner, the Grignard adds to the carbonyl carbon to form R–CH2–O–MgX. After hydrolysis, this alkoxide becomes the primary alcohol, giving R–CH2OH. This is in contrast to reactions with other aldehydes that already have an alkyl substituent on the carbonyl carbon, which would produce secondary alcohols (R–CH(OH)–R). Therefore the product is a primary alcohol after hydrolysis.