| In this study the skeleton copper (S-Cu) catalyst was applied to the catalytic hydrogenation system of p-chloride nitrobenzene (p-CNB) and the preparation of N.N-dimethylaniline derivatives from nitroaromatics in "one pot ". The microstructure of S-Cu was characterized by XRD, SEM, XPS and BET.At first, the S-Cu catalyst was used in the catalytic hydrogenation system of p-chloride nitrobenzene. Effects of various reaction conditions on the conversion of raw material and the selectivity of target product were investigated in detail. Under the optimized reaction conditions:m (p-CNB)=7mmol, m (S-Cu)=0.5g, V(CH3OH)=20mL,333K, and1.0MPa H2pressure. The conversion of p-CNB was100%and the selectivity of p-chloroaniline was up to97.9%in120minutes. Then the reaction mechanism was obtained according to the concentration-time plots.On the basis of catalytic hydrogenation system of p-CNB catalyzed by S-Cu, S-Cu was used in the preparation of4-chloro-N,N-dimethyl-benzenamine from p-CNB in "one pot". In this system p-CNB was used for substrate,37%formaldehyde solution was used for alkylation reagents, H2was used for reducing agent, and methanol was used for solution. Under the optimized reaction conditions:m (p-CNB)=6mmol, V (HCHO)=1.8mL, m (S-Cu)=0.5g, V (CH3OH)=20mL,373K, and1.3MPa H2pressure. The conversion of p-CNB was100%and the selectivity of4-chloro-N,N-dimethyl-benzenamine aniline was up to99.4%in60minutes. Then a possible reaction mechanism of hydro-dimethylation of p-CNB was put forward by investigating the relationships of component concentration versus reaction time.Inspired by these results, we investigated a series of nitroaromatics with different substituents. Under the experimental conditions, both of the conversion of raw material and the selectivity of target product were satisfactory. As expected, the substituent types and relative positions of nitroaromatics had important impact on the selectivity of target products. |
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