Study On Technology Improvement Of The Preparation Of 10-undecylenic Acid From Castor Oil

10-Undecylenic acid is the intermediate of medicine, perfume, surfactant and nylon-11. The preparation of 10-undecylenic acid from the alcoholysis, pyrolysis, hydrolysis of castor oil, the technology of alcoholysis is incomplete; the pyrolysis of methyl ricinoleate for 10-undecyleic acid methyl ester: it has some disadvantages, such as impure material, the pyrolysis is incomplete, a lot of side reactions, and etc, the yield of 10-undecylenic acid methyl ester is 44.2% and the yield of heptanal is 25.4%; the technology of hydrolysis is incomplete, the yield of product is low. The main work are as follows:The mixture of the alcoholysis of castor oil and methanol, the main ingredient was methyl ricinoleate. The optimum technological conditions were as following: molar ratio of castor oil to methanol was 1:4; catalyst was potassium hydroxide; reaction time was 3 hours; reaction temperature was 35℃; added chelator EDTA. The yield of alcoholysis mixture was 99.0%.Study on purification of methyl ricinoleate by two kinds of extraction. Direct extraction of the raw material: the extractant was the mixture of medium weight petroleum ether and 90% aqueous methanol, extraction temperature was 20~30℃, extraction time was 90 min, the yield of methyl ricinoleate was higher than 86.0%, the purity was higher than 97.0%. The extraction of adding the sunflower oil: the purification of methyl ricinoleate from castor oil methyl esters and refined sunflower oil by liquid-liquid extraction using 90% aqueous methanol, extraction temperature was 20~30℃, extraction time was 20 min, the yield of methyl ricinoleate was higher than 86.0%, the purity was higher than 94.0%.The pyrolysis of methyl ricinoleate for 10-undecylenic acid methyl ester and heptanal, the optimum technological conditions were as following: preheating temperature was 150℃; pressure was 8kPa; condensing temperature was-15℃; 0.5g/min of feeding rate; pyrolysis temperature was 490℃; antioxygen was 4-methoxyphenol. The yield of pyrolysis mixture was 87.91%, The yield of 10-undecylenic acid methyl ester was 50.21%, The yield of heptanal was29.65%.The hydrolysis of 10-undecylenic acid methyl ester for 10-undecylenic acid, the optimum technological conditions were as following: molar ratio of 10-undecylenic acid methyl ester to NaOH was 1:1.02; mass fraction of NaOH solution was 30%; saponification temperature was 80℃; saponification time was 6 hours; dilute sulfuric acid; acidification pH=6. The yield was 99.5%.