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以价格低廉的苯并噻唑为原料,合成了4种新型功能化布朗斯特酸性离子液体:苯并噻唑硫酸氢盐([HBth]-HSO_4)、苯并噻唑磷酸二氢盐([HBth]H_2PO_4)、苯并噻唑高氯酸盐([HBth]ClO_4)、苯并噻唑硝酸盐([HBth]NO_3),其结构经FT-IR、HRMS、NMR表征得到确认.考察了4种酸性离子液体在蓖麻油酸和乙二醇丁醚(EGBE)酯化反应中的催化活性,并与以浓硫酸为催化剂的催化体系相对照.结果表明:当n(蓖麻油酸)∶n(乙二醇丁醚)=1∶1.15,离子液体催化剂用量为蓖麻油酸重量的2%,反应温度90℃,反应时间5 h,酯化率可达98.8%,离子液体催化剂经真空干燥重复使用10次后,仍具有较高的催化活性.还考察了以苯并噻唑硫酸氢盐为催化剂催化合成系列蓖麻油酸二元醇醚酯和短链脂肪酸酯,也获得了较高的酯化率,且离子液体均能与酯产物自动分相.与传统硫酸催化酯化相比,此类离子液体催化酯化具有生产成本低、过程清洁、使用周期长等优点,完全可以替代传统浓硫酸催化蓖麻油酸酯化反应.
Four new functionalized Bronsted acidic ionic liquids were synthesized with cheap benzothiazole as the starting material: benzothiazole bisulfate ([HBth] -HSO_4), benzothiazole dihydrogen phosphate ([HBth] H_2PO_4 ), Benzothiazole perchlorate ([HBth] ClO_4) and benzothiazole nitrate ([HBth] NO_3) were synthesized and characterized by FT-IR, HRMS and NMR.The effects of four acidic ionic liquids on Ricinoleic acid and ethylene glycol butyl ether (EGBE) esterification reaction, and with concentrated sulfuric acid as a catalyst in the catalytic system.Results show that: when n (ricinoleic acid): n Ether) = 1: 1.15, the dosage of ionic liquid catalyst is 2% by weight of ricinoleic acid, the reaction temperature is 90 ℃, the reaction time is 5 h, the esterification rate can reach 98.8%. After the ionic liquid catalyst is vacuum dried for 10 times, Still has a higher catalytic activity.We also investigated the use of benzothiazole bisulfate as a catalyst for the synthesis of a series of ricinoleic acid glycol esters and short-chain fatty acid esters, also obtained a higher esterification rate, and the ion Liquid can be automatically separated from the ester product.Compared with the traditional sulfuric acid esterification, such ionic liquid catalytic esterification has a production cost Low, clean process, long life cycle, etc., can replace traditional concentrated sulfuric acid catalyzed acidification of ricinoleate.