Study On The Synthesis Of Branched Chain Alkyl Stearate By Transesterification

Branched chain alkyl stearate contains a long branched alkyl chain and one ester functional group, which provides it special character, for example, it is liquid in low temperature. Therefore, it can be used as the plasticizer in the PVC, the extension agent in the cosmetics, the additive in the advanced lubricant, the lubricant in the plastics processing, and the releasing agent in the polycarbonate. So the research of synthesis and application on branched chain alkyl stearate has high potential value in practice.This thesis researches the possibility of synthesizing the branched chain alkyl stearate by transesterfication reaction using methyl stearate and 2-ehyl-1-hexanol, 2-hexyl-1-decanol, 2-octyl-1-dodecanol as raw materials catalyzed by organic tin.The influencing effect of raw-materials, amount of catalysts, and reaction temperature, reaction time is discussed in detail.The best experimental conditions for transesterfications are identified. When the molar ratre of 2-ehyl-1-hexanol, 2-hexyl-1-decanol, or 2-octyl-1-dodecanol to methyl stearate is all 1.5, the Bu₂SnO amount was 1.14 mol% of methyl stearate, the reaction temperature is at 140℃, 170℃, 170℃, respectively, the reaction time is 2h, 3h, 3h, respectively, N2 flow velocity is all 30ml/min, the yield of stearate higher alcohol is 92.0mol%, 91.5mol%, 90mol%, respectively.In the process of the synthesis of 2-ethylhexyl stearate by transesterification catalyzed by Bu₂SnO, we researched the regeneration method of Bu₂SnO catalyst, The results show that ethanol and water mixture as precipitating agent is the best regeneration method. The recovery yield of Bu₂SnO was 82.5%.Catalytic performance of Bu₂SnO kept unchanged after three cycles. Catalyst Bu₂SnO before and after reaction is characterized by FTIR and XRD. The structure of regenerated catalyst is the same as initial catalyst.Dibutyltin oxide can react with methylsufonic acid or p-toluenesulfonic acid to give two new dibutyltin(Ⅳ) sulfonates. They were characacterized by UV, FTIR, 1H-NMR, 13C-NMR. When they are used as the transesterification catalysts, their catalytic activities are higher than that of Bu₂SnO because of the strong election-withdrawing effect of sulfonic groups. The stronger the electron-withdrawing effect of the substituent on the sulfonic group is, the greater the Lewis acidity of Sn is and the higher the catalytic activity is.