The best reaction conditions for the preparation of phenylalanine using benzyl chloride and ammonia are as follows:1. Use an excess of ammonia to ensure complete reaction of the benzyl chloride. Typically, a 5-10 fold molar excess of ammonia is used.2. The reaction should be carried out in a polar, aprotic solvent such as dimethylformamide DMF or dimethyl sulfoxide DMSO to facilitate the nucleophilic substitution reaction.3. The reaction temperature should be maintained between 0C and 5C to minimize side reactions and decomposition of the reactants.4. The reaction should be carried out under an inert atmosphere e.g., nitrogen or argon to prevent oxidation of the reactants and products.5. The reaction should be stirred continuously to ensure proper mixing and to maximize the reaction rate.6. After the reaction is complete, the mixture can be quenched with water to remove excess ammonia and any unreacted benzyl chloride. The product can then be extracted using an organic solvent e.g., ethyl acetate and purified using standard techniques such as recrystallization or chromatography.7. The yield and purity of the product can be determined using techniques such as NMR spectroscopy, mass spectrometry, and elemental analysis.