Syntheses of diphenylmethane derivatives on solid acid catalysts with controlled hydrophobicity, acidity, and reaction space

点击翻译按钮获取中文摘要

Catalyst heterogenization in syntheses of chemicals by homogeneous catalyses is important from the viewpoint of green chemistry. The purpose of this study is to find suitable solid acid catalysts for the following three reactions in which homogeneous catalysts are used in practical processes:(1) Synthesis of bisphenol F from formaldehyde and phenol, (2) Synthesis of bis(4-hydroxy-3, 5-dimethylphenyl)methane from formaldehyde and 2, 6-dimethylphenol, (3) Synthesis of bis(4-aminophenyl)methane from formaldehyde and aniline. The catalysts examined were various types of zeolite and mesoporous aluminosilicate molecular sieves(Al-MCM-41). All the reactions were carried out in liquid phase at atmospheric pressure. Commercial phenol, 2, 6-dimethylphenol, aniline, and formalin were used as reactants without purification. It is clarified in this study that weak acid sites are responsible for three reactions because of a high reactivity of formaldehyde and the following catalysts and reaction conditions for each reaction are suitable. That is, for reaction (1) the suitable catalysts are high silica H-beta zeolite and Al-MCM-41 and a high phenol/formaldehyde ratio is required to attain a high selectivity, for reaction (2) the suitable catalyst is Al-MCM-41 and the selectivity is almost 100% at any reactant ratios, and for reaction (3) the active catalysts are Al-MCM-41 and H-beta and USY zeolites, the selectivity is affected by reaction spaces, and USY exhibits the highest selectivity.