Study On Synthesis Of Cycloalkanemethanamine

This paper mainly studied the cycloalkylation and hydrogenation in the synthesis of cycloalkanemethanamine. The traditional method of cycloalkylation was use sodium ethylate as catalyst and ethanol as solvent, this method with the disadvantage of long reaction period and low yield. The cycloalkylation of diethyl malonate and ethyl cyanoacetate with alkyl dihalide was investigated by using comminuted potassium carbonate as a base and toluene as solvent in the presence of phase-transfer catalyst (PTC), which provided a conventional procedure with the advantage of short reaction period and high product yield. PTCs were essential to cycloalkylation of diethyl malonate and ethyl cyanoacetate, quaternary ammonium compound and polyethyleneglycol were used selectively. Nevertheless, the mixtures of them were more active because of "synergistic interactions". The reaction was not suitable conducted under solvent-free condition, water formed during the reaction was removed by azeotropic distillation with toluene throughout the reaction. The factors influencing the product yield were discussed and the mechanism and kinetic of the reaction were also studied on the basis of the experimental data, the reaction can be described by the pseudo-second-order kinetics, and then calculated the cycloalkylation activation energy. Pilot-plant of cycloalkylation was investigated in 1000 L reaction equipment, the yield of the optimum technique show stable performance and the pilot-plant test provides the basic infromations for industrial production.The cycloalkylation was investigated using microwave irradiation in the presence of PTC. As we known, solvents were very important to the reaction, the comprehensive study showed some less polar aromatic solvent (toluene) had better effect, comparing to dipolar solvents in cycloalkylation under microwave irradiation. The applications of ionic liquids were also studied, indicating the reactions with added ionic liquids into the solvent were more efficient. Since the early days of microwave synthesis, the observed rate accelerations compared to oil-bath experiments have led to speculation on the existence of so-called "thermal" and "non-thermal" effect, this article analyzed the affection on cycloalkylation on the basis of the experiment data.In comparison with noncrystalline Ni-B nanoparticales and Raney Ni catalysts, the noncrystalline Ni-B nanotubes exhibited higher activity and better selectivity in the hydrogenation of cycloalkanecarbonitrile. The higher catalytic activity of the nanotubes can be partially ascribed to their larger surface area and good hydrogen storage properties. Especially, the negative curvature of the nanotube's inner surface can enhance the coordination of reaction molecules by the multiple active centers, which should affect the reaction equilibrium and result in an increase in the yield of cycloalkanemethanamine. Transmission electron microscopy (TEM) was used to determine the characterization and stability of the nanotubes. Noncrystalline Ni-B nanotubes exhibited higher activity and better selectivity in the hydrogenation of chloronitrobenzene compared wtih noncrystalline Ni-B nanoparticales and Raney Ni catalysts.The effect of the preultrasonication on the catalytic performance of noncrystalline Ni-B nanotubes was investigated in selcetive hydrogenation of cycloalkanecarbonitrile to cycloalkanemethanamine. The results demonstrated that employment of ultrasonic wave had benefit on the maintenance of catalyst activity. The mechanic of ultrasonic hydrogenation of cycloalkanecarbonitrile under normal pressure was discussed on the basis of the "cavitation effect". The activation energy of the reaction was calculated, which had no obvious changed under ultrasonic compared with traditional hydrogenation. The noncrystalline Ni-B nanotubes also exhibited good activity for hydrogenation of nitrobeneze under ultrasonic irradition at atmospheric pressure.