Question

Which of the following compounds can form a zwitterion ?

• A. Aniline
• B. Benzoic acid
• C. Acetanilide
• D. Glycine

Answer 1

The Correct Option is D

To determine which of the given compounds can form a zwitterion, we need to understand what a zwitterion is. A zwitterion is a molecule that contains both positive and negative charges, but it is overall electrically neutral. Such structures usually occur in amino acids, where the amino group can accept a proton to become positively charged, and the carboxyl group can donate a proton to become negatively charged.

Let's analyze each compound:

1. Aniline: Aniline is an aromatic amine with the structure C_6H_5NH_2. It does not have carboxylic acid functionality, so it cannot form a zwitterion.
2. Benzoic acid: Benzoic acid has the structure C_6H_5COOH and primarily contains the carboxylic acid group. It lacks an amino group to form a zwitterionic structure.
3. Acetanilide: Acetanilide contains both aromatic and amide functionalities but does not have a free amino and carboxylic group pair that can ionize into a zwitterion.
4. Glycine: Glycine is a simple amino acid with the structure NH_2CH_2COOH. In aqueous solutions, the amino group can accept a hydrogen ion (proton) to become NH_3^+, while the carboxyl group can lose a hydrogen ion to become COO^−, forming the zwitterionic structure.

Given the analysis, Glycine is the compound that can form a zwitterion, as explained with its structural characteristics.