Purification Of D-α-Tocopherol Nicotinate

This study mainly focuses on the purification of d-α-tocopherol nicotinate using adsorption resin column chromatography and crystalization.The synthetic process of d-α-tocopherol nicotinate was a "one pot " process with p-toluene sulfonyl chloride,nicotinic acid,and d-α-tocopherol as raw material,pyridine as catalyst,and toluene as solvent.The purity of crude product was not less than 80%. The side reaction was also studied.Taking into account that the adsorption resin could easily be regenerated and reusable in industry,we studied the effects of flow rate,temperature,and load of sample while choosing No.9 macroporous adsorption resin as solid phase,and the mixture of methanol and hexane as mobile phase.The optimum conditions of resin column chromatography were as follows:with column dimensionΦ20 350 mm,the flow rate 1.5 ml/min,temperature 40℃,the load of sample 3 g/90 ml resin.The purity of d-α-tocopherol nicotinate increased to 93%from about 85%with recovery 95%,or increased to 95%with recovery about 84%.The solubilities of dl-α-tocopherol nicotinate with temperature in methanol, ethanol,propyl alcohol and isopropyl alcohol was studied,then established the index curves of solubility which provide a theoretical basis for the process of crystallization. Therefore the cooling crystallization as the purification method of d-α-tocopherol nicotinate was chosen.By examining crystallization solvents and liquid ratio,the optimum conditions of crystallization for d-α-tocopherol nicotinate were as follows:ethanol as solvent,the ratio of nicotinate to solvent was 80-90 mg / ml,cooling to -16℃,then remained for about 24 hours,drying the crystal by nitrogen,the purity of the samples were more than 99%.