May/June 2026 Paper 42

Alanine, CH${}_3$CH(NH${}_2$)COOH, is an amino acid that contains a chiral centre. Different synthetic routes to produce alanine can lead to the formation of an optically active sample or a racemic mixture. Describe what is meant by optically active.

Describe what is meant by racemic mixture.

Alanine has an isoelectric point of 6.11. Explain what is meant by isoelectric point.

Draw the structure of alanine at pH 10.

Alanine molecules can react together to form the tripeptide Ala–Ala–Ala. Draw the structure for this tripeptide. The functional groups formed should be displayed.

Compound $J$ can be synthesised from alanine in three steps, as shown in Figure 7.1.

Draw the structures of compounds $G$ and $H$ in the boxes in Figure 7.1.

Compound $J$ can be synthesised from alanine in three steps, as shown in Figure 7.1.

Suggest reagents and conditions for steps 1 to 3 in Figure 7.1.