The most efficient method for preparing phenylalanine from benzyl chloride and ammonia is through the Strecker synthesis. The Strecker synthesis is a three-step process that involves the following steps:1. Formation of imine: Benzyl chloride is first converted to benzaldehyde by hydrolysis. The benzaldehyde is then reacted with ammonia to form an imine intermediate.2. Cyanohydrin formation: The imine is reacted with hydrogen cyanide HCN to form a cyanohydrin.3. Hydrolysis: The cyanohydrin is hydrolyzed under acidic conditions to yield phenylalanine.Here's the detailed procedure:1. Hydrolysis of benzyl chloride: Heat benzyl chloride with water and a catalytic amount of sulfuric acid. The reaction will produce benzaldehyde and hydrochloric acid.2. Formation of imine: Add ammonia to the benzaldehyde solution and stir the mixture at room temperature for several hours. The reaction will produce an imine intermediate.3. Cyanohydrin formation: Slowly add hydrogen cyanide HCN to the imine solution while maintaining the temperature below 10C. The reaction will produce a cyanohydrin.4. Hydrolysis: Add the cyanohydrin to a solution of hydrochloric acid and heat the mixture under reflux for several hours. The reaction will produce phenylalanine and ammonium chloride.To ensure the purity of the product, the following steps can be taken:1. Purification by recrystallization: Dissolve the crude phenylalanine in hot water and allow it to cool slowly. The phenylalanine will crystallize out of the solution, leaving impurities behind.2. Chromatography: Use column chromatography to separate phenylalanine from any remaining impurities. A suitable stationary phase is silica gel, and a suitable mobile phase is a mixture of ethyl acetate and hexane.3. Confirm purity using analytical techniques: Analyze the purified phenylalanine using techniques such as infrared spectroscopy IR , nuclear magnetic resonance NMR , and mass spectrometry MS to confirm its purity and identity.Remember to follow safety precautions when working with hazardous chemicals such as hydrogen cyanide, and work in a well-ventilated area or a fume hood.