To prepare phenylalanine from benzyl chloride and ammonia, a chemistry student can follow the Strecker synthesis method. Here's the step-by-step process:1. First, prepare benzaldehyde from benzyl chloride. To do this, react benzyl chloride with an oxidizing agent like potassium permanganate KMnO4 or chromic acid H2CrO4 in an aqueous solution. This will convert benzyl chloride to benzaldehyde.2. Next, react benzaldehyde with ammonia NH3 to form an imine intermediate. This reaction is called an imine formation. Mix benzaldehyde and ammonia in a round-bottom flask and stir the mixture at room temperature for several hours. The imine will form as a precipitate.3. To convert the imine intermediate to an -amino nitrile, add hydrogen cyanide HCN to the reaction mixture. This step is called a cyanide addition. Be cautious when handling HCN, as it is highly toxic. Stir the mixture for several hours at room temperature.4. Finally, hydrolyze the -amino nitrile to obtain phenylalanine. To do this, add a strong acid like hydrochloric acid HCl or sulfuric acid H2SO4 to the reaction mixture. Heat the mixture under reflux for several hours. The -amino nitrile will be hydrolyzed to phenylalanine.5. To isolate the phenylalanine, cool the reaction mixture and filter the precipitate. Wash the precipitate with cold water and dry it to obtain the crude phenylalanine.6. To purify the obtained phenylalanine, recrystallize it from a suitable solvent, such as water or ethanol.To determine the purity of the obtained phenylalanine, you can use various analytical techniques, such as:1. Thin-layer chromatography TLC : This technique can be used to check the purity of the sample by comparing it with a known standard of phenylalanine.2. Melting point determination: Compare the melting point of the obtained phenylalanine with the known melting point of pure phenylalanine.3. High-performance liquid chromatography HPLC or gas chromatography GC : These techniques can provide quantitative information about the purity of the sample.Potential sources of error in the experiment include:1. Incomplete reactions: Each step in the synthesis may not go to completion, leading to impurities in the final product.2. Side reactions: Unwanted side reactions may occur, leading to the formation of by-products.3. Loss of product during isolation and purification: Some phenylalanine may be lost during the filtration, washing, and recrystallization steps.4. Contamination: The reagents, glassware, or solvents used in the experiment may introduce impurities into the final product.To minimize these errors, ensure that the reactions are carried out under the appropriate conditions, use high-quality reagents and clean glassware, and perform the isolation and purification steps carefully.