The Gabriel synthesis method is typically used for the preparation of primary amines. However, to prepare phenylalanine from benzyl chloride and ammonia, a modified approach can be used. The optimum conditions for this reaction are as follows:1. Concentration: - Benzyl chloride: 1.0 M - Ammonia: 5.0 M excess to drive the reaction to completion 2. Temperature: The reaction should be carried out at a temperature of 0C to minimize side reactions and improve the yield of phenylalanine.3. Reaction time: The reaction time can vary depending on the scale of the reaction and the efficiency of stirring. Generally, the reaction should be allowed to proceed for 24 hours to ensure complete conversion of benzyl chloride to the desired product.After the reaction is complete, the mixture can be neutralized with an acid such as hydrochloric acid to form the phenylalanine hydrochloride salt, which can then be isolated and purified. The free amino acid can be obtained by treating the salt with a base such as sodium hydroxide and extracting the phenylalanine using an organic solvent.