Study On The Synthesis Of 1, 7-heptaediol By Strong Acidic Functional Ionic Liquid

1,7-heptaediol is an important intermediates in fine organic synthesis, commonly used in polyester, petrochemicals, flavors and fragrances, cosmetics and other industries. It is also used in the pharmaceutical industry for manufacturing various types of ointments, softeners, solvents and other pills and can be used as additives in materials synthesis. In recent years, the increasing market demand for 1,7-heptaediol is attracting attentions at home and abroad. In this paper,1,7-heptaediol was prepared by two-step esterification and reduction reaction of 1,7-pimelic acid.A acidic ionic liquid was prepared and used as solvent and catalyst in the esterification reaction of 1,7-pimelic acid and ethanol. The esterification products can be easily separated from the reaction system. The effects of the reaction conditions on the reaction results, such as the amount of catalyst, molar ratio of acid and alcohol, reaction time, were examined and the optimal conditions were obtained through orthogonal design based on single-factor experiments. The optimal conditions are as follows:n(C2H5OH):n(C7H12O4)=3:1,1.00 g of catalyst, reaction time for 5.5 h at 108℃. Under the optimal reaction conditions, the yield can be 97.8%. Separated from the products, ionic liquids can be reused 5 times and the yield can reach 96.6%. Compared with the traditional catalyst of concentrated sulfuric acid, the ionic liquids have the advantages of good chemical stability, non pollution, less side reaction, good repeatability and not using organic solvent as hydrated solvent etc.The new ionic liquid with strong acid binuclear cationic is characterized by elemental analysis, IR, H NMR and other methods to verify the structure and purity. Its NMR spectrum signals are assigned to provide an important basis for identification of its structure.NaBH4/ZnCl2 system is used for the reduction of 1,7-diethyl pimelate and it is proved that this method is feasible. The effects of the reaction conditions on the reaction results, such as the feeding methods, the amount of catalyst, reaction time and reaction temperature, were examined and the optimal conditions were obtained. It shows that the feeding method plays a key role in the reaction. The yield of the ester can reach 79.2% when the molar ratio of sodium borohydride, zinc chloride and 1,7-diethyl pimelate is 3:3:1 and time of refluxing is 8 h. This method has the advantages of simple process, less side effects, mild reaction condition and high selectivity etc.