Chapter 6, Problem 6.75P

Interpretation Introduction

Interpretation:

It is to be explained why ${\text{NaOC(CH}}_{\text{3}}{\text{)}}_{\text{3}}$ is used instead of NaOH to deprotonate alkyl-substituted diethyl malonate.

Concept introduction:

The proton of the $-{\text{CH}}_{\text{2}}-$ group situated between the two carbonyl groups of diethyl malonate is relatively acidic due to the presence of the two electron-withdrawing carbonyl groups. A strong base such as the hydroxide ion $-{\text{OH}}^{\text{-}}$ can extract this proton.

The ease of this deprotonation also depends on the presence of a substituent on this carbon. An alkyl substituent reduces the acidity of this proton because the electron-donating character of an alkyl substituent reduces the electron-withdrawing effect of the carbonyl groups.