Final answer:
Aldehydes react with organometallic reagents to form primary alcohols. A Grignard or organolithium reagent adds a nucleophilic carbon to the electrophilic carbon of the aldehyde, forming an alkoxide that yields a primary alcohol upon protonation. This includes the reduction of aldehydes like glucose to alditols such as glucitol.
Step-by-step explanation:
When aldehydes react with organometallic reagents, they primarily form primary alcohols. A typical reaction involves the addition of an organometallic reagent, such as a Grignard reagent or an organolithium reagent, to the carbonyl group of the aldehyde. This reaction results in the formation of an alkoxide intermediate, which upon protonation yields a primary alcohol. The process is essentially an addition of a nucleophilic carbon from the organometallic species to the electrophilic carbon of the carbonyl group.
For example, in the reaction of acetaldehyde with an organometallic reagent, the product is ethanol, a primary alcohol. The general formula for this reaction would be R-MgBr (where R is the alkyl or aryl group from the Grignard reagent) added to CH3CHO, followed by acidic work-up to give R-CH2CH2OH.
Moreover, reduction to alditols is another reaction involving aldehydes, in which they are reduced to alcohols using reducing agents. A classic example is the reduction of D-glucose to D-glucitol.