level of impurities conforming to drug regulatory specifications the addition of an alcohol after concentration of the reaction mixture makes the product free flowing and constitutes an inbuilt purification step as it selectively dissolves associated impurities which are then removed during filtration the process is convenient and cost effective for commercial scale because the process obviates the need for an additional purification step in one embodiment of the present invention the reaction of 4 bis 2 chloroethyl amino l phenylalanine with hydrochloric acid in water is followed by concentration in presence of an organic solvent stirring of the concentrated mixture with an alcohol and separating the obtained solid to yield 4 bis 2 chloroethyl amino l phenylalanine hydrochloride i of desired purity in some embodiments aqueous hydrochloric acid is added to melphalan free base iv suspended in water at a temperature of about 15 u00b0 c to about 20 u00b0 c the mixture is stirred at about 15 u00b0 c to about 45 u00b0 c for 2 to 3 hours to give a clear solution containing 4 bis 2 chloroethyl amino l phenylalanine hydrochloride i in other embodiments the acid addition salt formation reaction may be carried out between about 25 u00b0 c and about 30 u00b0 c the isolation of the compound of formula i may be carried out by removing water azeotropically by addition of one or more organic solvents to the reaction mixture and concentrating the mixture under reduced pressure.