The most efficient and effective method to prepare phenylalanine from benzyl chloride and ammonia is through the Strecker synthesis. The Strecker synthesis is a well-established method for the preparation of -amino acids, including phenylalanine. Here's the step-by-step process to achieve the highest yield possible:1. Formation of imine: First, benzyl chloride is reacted with ammonia to form an intermediate imine compound. To achieve a high yield, use an excess of ammonia and ensure that the reaction is carried out at a low temperature around 0C . This will minimize side reactions and promote the formation of the imine.2. Cyanide addition: Next, the imine is reacted with a cyanide source, such as potassium cyanide KCN or sodium cyanide NaCN , to form a nitrile. This step should also be carried out at a low temperature to minimize side reactions and maximize the yield of the nitrile.3. Hydrolysis: The nitrile is then hydrolyzed to form the corresponding -amino acid, phenylalanine. This can be achieved by refluxing the nitrile with a strong acid, such as hydrochloric acid HCl , or a strong base, such as sodium hydroxide NaOH . The choice of acid or base will depend on the desired final form of the amino acid i.e., as a free acid or a salt . To achieve a high yield, ensure that the hydrolysis is carried out to completion by monitoring the reaction progress using techniques such as thin-layer chromatography TLC or nuclear magnetic resonance NMR spectroscopy.4. Purification: Finally, the crude phenylalanine product can be purified using techniques such as recrystallization, chromatography, or ion exchange. The choice of purification method will depend on the specific impurities present in the crude product and the desired level of purity for the final phenylalanine product.By carefully controlling the reaction conditions and using an excess of ammonia, it is possible to achieve a high yield of phenylalanine from benzyl chloride and ammonia using the Strecker synthesis.