The balanced chemical equation for the preparation of phenylalanine from benzyl chloride and ammonia is:C6H5CH2Cl + 2 NH3 C6H5CH2NH2 + NH4ClTo calculate the theoretical yield of phenylalanine, we first need to determine the moles of benzyl chloride:Moles of benzyl chloride = mass g / molar mass g/mol Molar mass of benzyl chloride = 12.01 C * 7 + 1.01 H * 5 + 35.45 Cl = 126.58 g/molMoles of benzyl chloride = 50 g / 126.58 g/mol = 0.395 molesSince the stoichiometry of the reaction is 1:1, the moles of phenylalanine produced will be equal to the moles of benzyl chloride:Moles of phenylalanine = 0.395 molesNow, we can calculate the mass of phenylalanine produced:Mass of phenylalanine = moles * molar massMolar mass of phenylalanine = 12.01 C * 9 + 1.01 H * 11 + 14.01 N * 1 + 16.00 O * 1 = 165.19 g/molMass of phenylalanine = 0.395 moles * 165.19 g/mol = 65.20 gThe theoretical yield of phenylalanine that can be obtained from 50 g of benzyl chloride and an excess of ammonia is 65.20 g.