Calcium Carbonate → L-Rhamnitol

24 g of Raney-nickel obtained by the method described above was added to 300 g of an aqueous solution containing 100 g of 6-deoxy L-mannose in a 1-L glass autoclave with an agitator and a thermometer, to which water was added to a final reaction volume of 600 g. So as to adjust the reaction mixture to pH 7, then, calcium carbonate was added. Reaction was progressed while the temperature was retained at 50° C.; the hydrogen pressure was retained at 12 kg/cm2 (gauge pressure); the agitation speed was retained at 700 rpm. The reaction mixture was analyzed by HPLC. Consequently, 6-deoxy L-mannose was decreased to 1% in the 8-hour reaction, to produce 6-deoxy L-mannitol.