Sodium Hydroxide → L-Methionine

A mixture of 13.1 g of 98% sodium hydroxide pellets (0.32 mole) and 17.4 g (0.10 mole) of 5-(beta-methylmercaptoethyl)-hydantoin in 100 ml of water-saturated n-hexanol was heated to boiling over 25 minutes and refluxed with stirring for 26 minutes, after which the reaction mixture was quenched. The cold reaction mixture was stirred with 75 ml water for 1/4 hour, and the aqueous phase was separated. The organic phase (n-hexanol) was washed with four 25 ml portions of water. The combined, filtered, aqueous phases were neutralized to pH of 6 with concentrated hydrochloric acid, stirred at room temperature for the crystallization of methionine, and stored at 5° C. The reaction product was collected, washed with water, and dried to give 3.2 g of methionine, m.p. 268° C. decomposition. The combined mother-liquor and washings were concentrated to about 80 ml during which methionine crystallized. After the mixture had been chilled at 5° C., the reaction product was collected, washed with water, and dried to obtain 3.5 g of methionine, m.p. 268° C. decomposition.