Organic Chemistry MCAT Practice Exam

What characterizes the Gabriel malonic ester synthesis?

1. It is stereoselective

2. It involves deprotonation of phthalimide

3. It requires heat for all steps

4. It can directly yield an amide

The correct answer is: It involves deprotonation of phthalimide

The Gabriel malonic ester synthesis is characterized by the deprotonation of phthalimide, which is essential for generating a nucleophile that can participate in nucleophilic substitution reactions. In the synthesis, phthalimide is first treated with a strong base to deprotonate the amide nitrogen, creating a reactive species that can attack an alkyl halide. This reaction pathway is crucial because it allows for the formation of a carbon chain, extending it through the introduction of an alkyl group. The process makes use of malonic ester as a key component, which undergoes further transformations to ultimately yield a carboxylic acid. However, the pivotal step initiating the synthesis involves the deprotonation of phthalimide to facilitate the nucleophilic attack. In contrast, while stereoselectivity can be a feature of many organic reactions, it's not specifically characteristic of the Gabriel malonic ester synthesis. The requirement for heat is not universal; while some steps may require heat, it is not necessary for the reaction to proceed. Finally, while the overall process can lead to the formation of amides, it does not do so directly; instead, it produces a carboxylic acid that can be further processed