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It is obtained by the dehydration of sorbitol into anhydride and the esterification of anhydride and excessive stearic acid, or by direct heating and esterification of sorbitol and stearic acid in the presence of catalyst. Put 1mol sorbitol into the reactor, vacuumize it and heat it for dehydration. After dehydration, press 3mol of melted stearic acid and 1kg of sodium hydroxide catalyst into the reactor. Then increase the temperature slowly under the reduced pressure condition, raise it to 180℃ within 2h, then increase 10℃ per 1h, so that raise temperature to 210℃ after 3h, then hold the temperature at 210℃ for 5h, then raise temperature to 220℃ for reaction for 1h, and then take samples and measure the acid value. When the acid value reached 13 to 15, stop the process of esterification. Let it stand and cool it overnight. Then remove the coking substance at the lower layer, decolorize the upper layer with an appropriate amount of hydrogen peroxide, and finally heat up to 100℃ for hot pressing molding, finally finished product will be produced after cooling and packaging.
Identification test:
1. Solubility: It si insoluble in toluene, ether, carbon tetrachloride and ethyl acetate; It can be dispersed in petroleum ether, mineral oil, vegetable oil, acetone and dichewy alkane. Insoluble in water, methanol and ethanol.
2. Freezing point: An+ L to 50℃, which is measured by conventional method.
Content analysis:
First, accurately weigh about 25g sample and move it into a 500ml round-bottom flask. 250ml ethanol and 7.5g potassium hydroxide will be added and mixed up. Connected with the condenser, conduct the process of heating reflux for 1 to 2h, and then move it into an 800rnl beaker, wash the flask with 100ml water, which is also incorporated into the beaker. The ethanol is vaporized by heating it in a steam bath, and water is added at the right time to replace the ethanol until the ethanol smell cannot be detected for a long time. Add hot water to the total volume of about 250ml, neutralize the saponification solution with 1:2 dilute sulfuric acid, and add 10% more, heat and stir it up until the fatty acid layer is precipitated. The fatty acids then are transferred into a 500ml separator funnel, and the polyols are washed out with hot water for 3 to 4 times (20ml each time). The solution is combined with the original saponified polyols water layer. The combined water layer obtained by petroleum ether extraction for three times at a time of 20ml is added to the fatty acid layer and transferred to a weighed evaporator for evaporation until it is dry, and then cool and weigh the product, which is the content of the fatty acid. In addition, the polyols are neutralized with 1:10 potassium hydroxide solution to pH7 (measured with pH meter). The solution is vaporized into wet slag, and the polyols are separated from the salts for several times with hot ethanol: the ethanol extract (held in a weighed evaporator) is evaporated to dry in a steam bath, then cool and weigh it. Excessive drying and heating should be avoided. Another 25g sample are taken to determine the content of sorbitan anhydride.
