优质失水山梨醇单硬脂酸酯的合成

Synthesis of high quality sorbitan monostearate

以山梨醇和硬脂酸为原料,采用先醚化后酯化的二步法合成失水山梨醇单硬脂酸酯。研究了各主要影响因素对目标产物的色泽和三项指标(酸值、羟值、皂化值)的影响,研究发现醚化催化剂的种类影响目标产物的色泽;产物的皂化值随硬脂酸与山梨醇物质的量比的减小而减小;产物的羟值随醚化脱水增多而下降。研究得到了适宜的反应条件,即醚化反应条件:温度165℃、时间70min、WH3PO4+KH2PO4=0.60％;酯化反应条件:温度195～200℃、WNa2CO3=0.70％～0.80％、时间180min。经分析,实验得到的目标产物和扩试产物三项指标均合格,产物为乳白色。单酯和双酯的质量分数大于国内同类产物。

Sorbitan monostearate (Span 60) is synthesized from sorbitol and stearic acid by two-step method (etherification followed by esterification), and the influences of main factors on the product color and three quality indexes (acid value, hydroxyl value and sa-ponification value) are investigated. It is found that the kind of catalyst of etherification is an important factor to gain qualified product with a light color, the saponification value of the products decrease with decreasing of the molar ratio of stearic acid to sorbitol,and the hydroxyl value of products reduces as the improvement of the dehydration in etherification. The suitable reaction conditions are obtained, i. e. , for etherification, reaction temperature is 165℃, reaction time is 70 min and w(H3PO4+KH2PO1 )=0. 60% ; for esterification, reaction temperature is 195-200℃,w(Na2CO3) = 0. 70% -0. 80%, and reaction time is 180 min. Analytical results show that the three quality indexes of all samples from laboratory and pilot plant tests are eligible, the color of product is ivory and the mass fractions of monoester and diester are higher than that of the domestic similar products.