14P - Organic Chemistry (Mcmurry)

Question

Question: Which of the following compounds cannot be prepared by an acetoacetic ester synthesis? Explain.

(a) Phenylacetone

(b) Acetophenone 

(c) 3,3-Dimethyl-2-butanone

 

Step-by-Step Solution

Answer

All the provided ketones in (a), (b), and (c) cannot be prepared  

Step 1: Introduction

The common ketone group that is formed due to acetoacetic ester synthesis is .The R-group comes from alkyl halide.

Step 2: (a) Phenylacetone

To prepare Phenylacetone, chlorobenzene is required for the alkyl halide part. The chlorobenzene cannot take part in S_N² substitution. For this reason, Phenylacetone cannot be prepared by an acetoacetic ester synthesis.

(b) For Acetophenone

The acetoacetic ester provides $-C{H}_{2}COC{H}_3$  group to the product. As Acetophenone does not have this group, so Acetophenone cannot be prepared by an acetoacetic ester synthesis.

(c) For 3,3-dimethyl-2-butanone

The acetoacetic ester provides –CH₂COCH₃ group to the product. As 3,3-dimethyl-2-butanone does not have this group, 3,3-dimethyl-2-butanone cannot be prepared by an acetoacetic ester synthesis.