6853-87-8

1187-84-4

6853-87-8

General procedure for the synthesis of S-methyl-L-cysteine sulfoxide (MCSO) from S-methyl-L-cysteine (MCS): (1) The purified MCS (0.2 mol) was dissolved in 300 mL of distilled water, and 0.25 mol of 30% hydrogen peroxide solution was slowly added under magnetic stirring with continuous stirring for 12 h at room temperature to obtain a crude MCSO solution. (2) After filtration to remove insoluble impurities, 2 L of anhydrous ethanol was added to the solution and allowed to stand at 4 °C for 12 h. MCSO crystals were precipitated. The crystals were collected by filtration and dried at 50 °C to obtain 28 g of MCSO. (3) Dissolve the MCSO crystals obtained in step (2) in 120 mL of distilled water, heat to 50°C, add preheated dilute acetone solution (77 mL of distilled water mixed with 394 mL of acetone), and cool to room temperature. (4) The solution was allowed to crystallize at 4°C for 6-12 hours, dried and filtered to yield 6.9 g of crystals. (5) The resulting crystals were dissolved in 23 mL of distilled water, a preheated second dilute acetone solution (19 mL of distilled water mixed with 95 mL of acetone) was added, hot-filtered and cooled to room temperature. (6) Crystallize by standing at 4°C for 6-12 h. Filter and dry to yield 3.5 g of crystals. (7) Dissolve the crystals in 11.5 mL of distilled water, add preheated third dilute acetone solution (10 mL of distilled water mixed with 45 mL of acetone), hot filter and cool to room temperature. (8) Crystallization was allowed to stand at 4°C for 6-12 hours, resulting in about 2.82 g of pure (+)-MCSO. [0050] The MCSO sample was dried to constant weight, accurately weighed and dissolved in distilled water to prepare a 1 mg/mL solution. Spectrophotometry was determined in a WXG-4 disk spinner at 20°C and 589.3 nm using a 10 mm microtube.