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Lin X.,Zhejiang University | Zhao Y.,Zhejiang University | Zhang S.,Zhejiang University | Wang L.,Jiangsu Qingquan Chemical Co. | And 2 more authors.
Catalysis Communications | Year: 2014

Synthesis of 3,3′-dimethyl-4,4′-diaminodiphenylmethane (MDT) from o-tolylamine and formaldehyde over zeolites was investigated. Among the three tested zeolites, Hβ showed higher catalytic activity than HY and HZSM-5 for MDT synthesis. In the case of Hβ as a catalyst, the effects of feed composition, reaction time and temperature on the yield and selectivity of product MDT were further examined to optimize process conditions. In an o-tolylamine:formaldehyde = 8:1 molar ratio, the two-step reaction running at 413 K for 0.5 h and then 433 K for 0.5 h gave the MDT yield of 87.5%. © 2013 Elsevier B.V.

Yang Y.,Zhejiang University | Zhao Y.,Zhejiang University | Shao J.,Jiangsu Qingquan Chemical Co. | Zhang S.,Zhejiang University | Yang R.,Jiangsu Qingquan Chemical Co.
Journal of Molecular Catalysis A: Chemical | Year: 2015

Heterogeneous synthesis of 3,3′-dimethyl-4,4′-diaminodiphenylmethane (MDT) from o-tolylamine and formaldehyde on acidic zeolites HY, HZSM-5, Hβ and TS-1 was investigated. Hβ zeolite with strong Bronsted acidity and proper textural property demonstrated better catalytic performance than other three zeolites for this synthetic reaction. Yield and selectivity of product MDT from the catalytic reaction over Hβ strongly depended on temperature, and optimal reaction temperature appeared to be about 433 K. Based on analyses of LC/MS and 1H NMR for reaction intermediates, it was suggested that the synthetic process went through multiple steps involving intermediates o-tolylamino-methanol, methylene-o-tolylamine, N,N′-di-o-tolyl-methanediamine and 2-methyl-4-(o-tolylamino- methyl)-phenylamine. Interpretation to the mechanism of various intermediates formation and conversion was presented. © 2014 Elsevier B.V. All rights reserved.

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