Synthesis of 4,4鈥?Methylenedianiline Catalyzed by SO3H-Functionalized Ionic Liquids

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• 作者：Jinping Tian ; Hualiang An ; Xiaomeng Cheng ; Xinqiang Zhao ; Yanji Wang
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2015
• 出版时间：August 12, 2015
• 年：2015
• 卷：54
• 期：31
• 页码：7571-7579
• 全文大小：483K
• ISSN：1520-5045

文摘

4,4鈥?Methylenedianiline (4,4鈥?MDA) is a key intermediate for the production of polyurethanes. A series of SO₃H-functionalized ionic liquids (SFILs) were synthesized, and their catalytic performance was evaluated in the condensation reaction of aniline with formaldehyde for the synthesis of 4,4鈥?MDA. The result showed that SFILs had excellent catalytic activity, and their catalytic activity was consistent with their acid strength. [HSO₃-bmim]CF₃SO₃ (SImTf) with the highest acid strength showed the best catalytic activity. Then, the influence of reaction conditions on the condensation reaction of aniline with formaldehyde to 4,4鈥?MDA was investigated using SImTf as the catalyst, and suitable reaction conditions were obtained as follows: molar ratio of aniline to formaldehyde = 5, mass ratio of SImTf to formaldehyde = 3.5, reaction temperature of 80 掳C, and reaction time of 8 h. Under the above reaction conditions, the conversion of aniline was 36.3%, and the yield and selectivity of 4,4鈥?MDA were 79.4% and 87.9%, respectively. However, the catalytic activity of the recovered SImTf declined dramatically. The results of UV鈥搗is and FT-IR spectroscopy analyses showed that there was a chemical interaction between SImTf and aniline. The deactivated SImTf could be regenerated by acidization with trifluoromethanesulfonic acid, and the acidized SImTf could be reused four times with a tolerable loss of its catalytic activity. Meanwhile, a plausible catalytic reaction mechanism for the synthesis of 4,4鈥?MDA was proposed.