Separately, a 1.0 liter mixing vessel equipped with a calcium chloride-containing tube was charged with 402.7 g (1.50 moles) of 1,2-epoxyoctadecane. While the charged 1,2-epoxyoctadecane was stirred at room temperature, a concentrated sulfuric acid was gradually dropped in an amount of 2.7 g (0.027 mole) into 1,2-epoxyoctadecane. After stirring for 15 minutes, the resultant mixture was placed into the dropping apparatus attached to the reaction vessel and was dropped into the 1,2-propanediol contained in the reaction vessel and maintained at a temperature of 70 to 75° C. over a time of 2 hours. Then the reaction of the mixture was carried out at a temperature of 70 to 75° C. for one hour. After the exhaustion of the starting material, namely 1,2-epoxydodecane was confirmed by a thin-layer chromatography, the reaction was stopped. A powdered sodium hydrogen carbonate was mixed in an amount of 2.5 g (0.03 mole) into the resultant reaction liquid in the reaction vessel, the resultant mixture was stirred for 30 minutes to neutralize the reaction liquid. From the reaction liquid, the precipitated crystals were separated by filtration. A 1,2-propanediol monohydroxyoctadecyl ether mixture was obtained in an amount of 510.9 g (yield: 96.7%).
