What compound is formed when methyloxirane is reacted with ethylmagnesium bromide followed by treatment with aqueous acid?

A) 1-pentanol
B) 2-pentanol
C) 2-methyl-1-butanol
D) 2-methyl-2-butanol
E) 3-methyl-1-butanol

The reaction between methyloxirane (a three-membered epoxy ring with a methyl group attached) and ethylmagnesium bromide (a Grignard reagent) involves the nucleophilic attack of the ethyl group on the less hindered carbon atom of the oxirane ring, leading to ring opening. This results in a primary alcohol after the addition of the ethyl group to the carbon atom next to the methyl group. Upon subsequent treatment with aqueous acid, protonation occurs, yielding the alcohol. The product is 2-pentanol, as the ethyl group attaches to the second carbon in the chain, counting from the end nearest the original methyl group, making a five-carbon chain with the hydroxyl group on the second carbon.