High School

What ester and what Grignard reagent(s) might you start with to prepare the following alcohol? Remember that Ph represents a phenyl group.

(a) Reaction: \(\rightarrow\) (2. \(H_3O^+\)) (1. 2PhMgBr)

(b) Reaction: \(\rightarrow\) (2. \(H_3O^+\)) (1. 2CH\(_3\)CH\(_2\)MgBr)

(c) Provide the corresponding ester and Grignard reagent for this synthesis.

Answer :

Final answer:

The Esther is PhCH2COOH (Phenylacetic acid) - This ester has a two-carbon chain required for the target alcohol. Grignard reagent: Not required (Target molecule is already an alcohol) The answer is option (c).

Explanation:

Here's the breakdown for each option:

(a) PhMgBr (phenylmagnesium bromide)

  • Reacting with PhMgBr would lead to a secondary alcohol after hydrolysis due to the carbonyl group (C=O) in the ester being converted.

  • However, the target molecule in option (c) is a primary alcohol. So, option (a) is not suitable.

(b) CH3CH2CH2MgBr (propylmagnesium bromide)

  • Using propylmagnesium bromide would create a 4-carbon chain alcohol (Ph-CH2-CH2-CH2-OH).

  • This doesn't match the target structure in option (c) which has a 2-carbon chain. Therefore, option (b) is not viable.

(c) CH2-CH2-Ph-OH

  • This option directly represents the target molecule itself (phenylethanol).

  • Since it's already an alcohol, there's no need for a Grignard reagent for its preparation.

Out of the options provided, you won't need a Grignard reagent for option (c)