Final answer:
The reaction of butanal with one equivalent of a Grignard reagent yields a secondary alcohol, as a result of nucleophilic addition to the carbonyl group.
Step-by-step explanation:
When butanal reacts with one equivalent of a Grignard reagent, the product formed is a secondary alcohol. This reaction occurs through the nucleophilic addition of the Grignard reagent to the carbonyl group of butanal.
The Grignard reagent adds across the double bond of the aldehyde, resulting in the formation of a new carbon-carbon bond and a metal alkoxide intermediate, which upon protonation gives a secondary alcohol.