Study on the Synthesis of Di(3,4-methyl) Benzylidene Sorbitol

Di (3,4-methyl) benzylidene sorbitol (briefly referred as “ DMDBS ”), used as transparency nucleating agent in crystallinity polyolefin kind resin, can dramaticly reduce the haze of plastic products, improving their quality in transparency, resin’s rigidity, heat resistant temperature and modulus of bending. DMDBS, having these characteristics, has been widely used as polyolefin processing auxiliary. With the presence of hydrophobicity organic solvent and lower alcohol, the nucleating ag…

Study on the Synthesis of Di(3,4-methyl) Benzylidene Sorbitol

Di (3,4-methyl) benzylidene sorbitol (briefly referred as" DMDBS "), used as transparency nucleating agent in crystallinity polyolefin kind resin, can dramaticly reduce the haze of plastic products, improving their quality in transparency, resin's rigidity, heat resistant temperature and modulus of bending. DMDBS, having these characteristics, has been widely used as polyolefin processing auxiliary.With the presence of hydrophobicity organic solvent and lower alcohol, the nucleating agent of DMDBS can be synthesized by one mole sorbitol and two mole 3,4-dimethyl benzaldehyde, during which the aldehyde and six hydroxyl of sorbitol condensate. The chemical reaction equation can be expressed as:To thoroughly inspect the characters of the reaction, a series of experiments is carried out in 14 liter agitator, with temperature at 75 ℃, and agitation velocity at 375r/min. From the result of the experiments, it can be concluded:The 3,4-dimethyl benzaldehyde/sorbitol(B/S) has influence on the reaction. When B/S is 2, the target product's yield can reach 98.79%. However the product's yield will descend definitely, if B/S is reduced or increased.Catalyst is the second effective element. When the acid catalyst is little, the reaction is slow.Increasing the use level of the acid catalyst can accelerate the reaction. However, we find overdose of the acid catalyst will yield more by-product tri-condensation. So there is an optimal use level range of the acid catalyst. From the experiments, we find the use level of the acid catalyst between 1.2% and 1.5% is acceptable, and we choose 1.3%.The third effective affecting element is reaction time. With the reaction temperature at 75℃, B/S at 2, the use level of the acid catalyst at 1.3%, when the reaction time reaches 2 hours, the product's yield is below 80%, as the reaction time increases to 6 hours, the product's yield peaks to 98.79%. If we keep increasing reaction time, however, the product's yield will not increase further, indicating the condensate reaction is finished.This reaction is a liquid-liquid non-homogeneous process. The quantity of lower alcohol, which can validly improve the liquid-liquid miscibility state, has an remarkable effect on the reaction.When adding nothing, the reaction is slow, if we add lower alcohol, the product's yield and selectivity will all be improved. However, to some point if we keep increasing the dose of lower alcohol, the product's yield and selectivity will not rise further. From the experiments, we find the optimal dose of lower alcohol is 15%.Conclusion, the optimal condition for the reaction is reaction temperature at 75 ℃, B/S at 2, the use level of the acid catalyst at 1.3%, reaction time at 6 hours, lower alcohol at 15%.