The synthesis of phenylalanine from benzyl chloride and ammonia can be carried out through the following steps:1. Nucleophilic substitution of benzyl chloride with ammonia to form benzylamine2. Protection of the amine group in benzylamine3. Reaction with a protected form of alanine4. Deprotection of the amine and carboxylic acid groups to obtain phenylalanineFor the first step, the optimal reaction conditions for the nucleophilic substitution of benzyl chloride with ammonia are as follows:Temperature: The reaction should be carried out at low temperatures, preferably between 0C and 5C, to minimize the formation of by-products.Pressure: The reaction can be performed under atmospheric pressure.Concentration: The reaction should be carried out in a solvent that can dissolve both reactants, such as a mixture of water and an organic solvent like ethanol. The concentration of ammonia should be in excess e.g., 2-3 equivalents to ensure complete conversion of benzyl chloride to benzylamine.For the subsequent steps, the optimal reaction conditions will depend on the specific protecting groups and coupling reagents used. Generally, these reactions are carried out at room temperature or slightly elevated temperatures e.g., 40-60C and under an inert atmosphere e.g., nitrogen or argon to prevent oxidation or hydrolysis of sensitive functional groups.It is important to note that the overall yield of phenylalanine will depend on the efficiency of each step in the synthetic sequence. To achieve the highest yield, it is crucial to optimize the reaction conditions for each step and to carefully purify the intermediates to minimize the formation of by-products and side reactions.