离子液体催化甘油合成三醋酸甘油酯

采用两步法合成离子液体——正-丙基磺酸-三乙基对甲苯磺酸铵,并用FT-IR,¹H NMR和¹³C NMR对其结构进行表征.以该离子液体为催化剂,考察反应时间、反应温度、物料配比和离子液体用量对纯甘油与醋酐合成三醋酸甘油酯的产率的影响规律.结果表明:当反应温度为100 ℃,反应时间为3 h,n(甘油)∶n(醋酐)∶n(离子液体)=1.0∶4.0∶0.1时,三醋酸甘油酯的产率最高可达到96%.用甲苯萃取三醋酸甘油酯,回收得到的离子液体循环使用3次,三醋酸甘油酯的产率没有明显下降,说明离子液体的稳定性和循环使用性较好,且催化合成生物柴油时,离子液体的用量正好适用于继续催化副产物甘油与醋酐发生酰化反应生成三醋酸甘油酯.

Synthesis of Triacetin Catalyzed by Ionic Liquid With Glycerol

Ionic liquid ［Et₃N(CH₂)₃SO₃H］-［p-CH₃(C₆H₄)SO₃］ was prepared by two-step method, and its structure was characterized by FT-IR, ¹H NMR and ¹³C NMR. The effects of reaction time, reaction temperature, molar ratio of acetic anhydride to glycerol, and catalyst dosage on the yield of triacetin were investigated using this ionic liquid as catalyst. The results showed that, the yield of triacetin could reach 96% under the conditions of molar ratio of n(glycerol)∶n(acetic anhydride)∶n(ionic liquid)=1.0∶4.0∶0.1, reaction temperature 100 ℃, and reaction time 3 h. The triacetin was extracted by toluene, and the yield had no obvious reduction when the catalyst recovered and reused for 3 times. The results indicate that the ionic liquid is stable and reusable well, and the dosage used in biodiesel synthesis is just suitable to catalyze by product glycerol, with acetic anhydride to generate triacetin.