Study On The Preparation Of High Content Of Natural α-TocopheroI

The main work of this paper is to study how to improve the yield of the natural high content of a-tocopherol on basis of the existing process. Optimization of preparation process conditions of a-tocopherol with method of aminomethylation-extraction, analysis of the product and byproducts of a-tocopherol, a-tocopherol was separated from waste hexane with method of column chromatography, and studying on new technology of preparation of a-tocopherol with method of aminomethylati on-column chromatography were included in this paper.Mixed tocopherols concentrate (MTC) was transformated and enriched with method of aminomethylation-extraction, optimal conditions were determined through the study of factors on every reaction. Aminomethylation reaction:Dosage molar ratio of MTC, formalin (37wt%), and dimethylamine (40wt%) was1:3:3, the reaction at80℃for2.5h under a nitrogen atmosphere with cyclohexane as solvent; Extraction:acetic acid (70wt%) and n-hexane as extractants (1:1, v/v), the reaction was stirred for40min under temperature at45℃; Hydrogenolysis reaction:Weight ratio of Pd/C to tocopherols intermediate1.0g/50g, reaction conducted in in the autoclave for4.0h, with a hydrogen pressure of3.0MPa and temperature of200℃. Ultimately, three different contents of MTC,36.3%,40.9%, and51.7%, was transformed and concentrated to high content of a-tocopherol, and their purity were91.38%,89.73%,92.17%, yield were70.45%,76.40%,65.62%respectively.Analysis results of a-tocopherol and high boiling component showed that high boiling component contained a-tocopherol with content of23%, and other ingredient were tocopherols derivatives. The small amount of a-tocopherol could be obtained by molecular distillation or solvent extraction to increase final yield.Low content of a-tocopherol could be separated from waste hexane with method of column chromatography. Silica gel as the stationary phase, a mixed solvent of methylene chloride-ethyl acetate as eluent to separate a-tocopherol, and the value of membership degree of purity and recovery as evaluation criteria of separation efficiency. When eluent methylene chloride-ethyl acetate (99.5:0.5, v/v), flow rate was1.5mL/min, the sample volume was0.75g, purity of a-tocopherol could be improved from16%to88.75%, and yield was38.84%.With the combination of aminomethylation-extraction and column chromatography, a new process of aminomethylation-column chromatography was explored to prepare natural high content of a-tocopherol. The aminomethylation reaction conditions remain unchanged, the hydrogenolysis reaction was improved, and the separation conditions of column chromatography were optimized based on orthogonal test, including terrible and variance analysis, to obtain the optimal separation conditions. When eluent methylene chloride-ethyl acetate (99:1, v/v), flow rate was1.0mL/min, the sample volume was0.75g, three different contents of MTC,36.3%,40.9%, and51.7%, was transformed and separated to high content of a-tocopherol, and their purity were90.77%,89.84%,93.15%, yield were62.66%,64.08%,76.16%respectively. Comparing two preparation processes, results showed that the former was suitable for low content of MTC and a-tocopherol, while the latter was superior to high content of MTC.