Study On The Catalytic Synthesis Of N-alkylated Aniline And Triacetonamine

N-alkylated anilines are important fine chemical intermediates and widely appliedin dye, agricultural chemicals and pharmaceuticals. Reductive N-alkylation ofnitroarenes with alcohols is one of the promising methods for the preparation of thesekinds of compounds. The synthesis of N-alkylated anilines is systematicallyinvestigated and a continuous process for the synthesis of N-alkylated aniline isestablished in this paper.1、The synthesis of N-benzylaniline from reductive N-alkylation of nitrobenzenewith benzyl alcohol was taken as a model for the investigation into the reductiveN-alkylation of nitrobenzenes with alcohols. A series of Cu-based catalysts wereprepared and examined, and Cu30Cr5/γ-Al2O3was chosen as the best catalyst. Thus,the reaction parameters were optimized. A90.6％selectivity of N-benzylaniline wereobtained from nitrobenzene complete conversion under the optimum reactionconditions (200℃reaction temperature，3MPa hydrogen pressure,0.3ml/min feedrate). The catalyst exhibited good catalytic performance within100hours. Thegenerality of the present Cu30Cr5/γ-Al2O3catalyzed system with regard tonitrobenzene derivatives and alcohols was examined and the corresponding productswere obtained in yield more than90％.2、The catalysts were catalyzed by XRD、XPS、BET and H2-TPR. It was foundthat Cu0was believed to be the active sites of the catalysts. The addition of Cr intoCu30/γ-Al2O3led to highly dispersion of Cu0particles, which inhibited theaggregation and sintering of copper and improved the lifetime of the catalyst.Triacetoneamine is the sole precursor for the synthesis of hindered amine lightstabilizer and is the foundation of hindered amine light stabilizer industry. Up to now,the synthesis of triacetoneamine with an intermittent process in the autoclave has beenwidely employed at home and abroad in the presence of ammonium nitrate as catalyst.The use of large amounts of sodium hydroxide had negative influence on environment.We established a process for the continuous synthesis of triacetoneamine usingzeolites and cation exchange resins as catalysts in a fixed-bed reactor.1、The synthesis of triacetoneamine from acetone and ammonia was studied. HYzeolite was selected, and the mechanism for the preparation of triacetoneamine wasproposed. The conversion of acetone reached49.1％with a selectivity oftriacetoneamine of41.25％under the optimized reaction conditions (60℃reaction temperature，6:1acetone to ammonia molar ratio and0.26ml/min feed rate).2、A series of cation exchange resins were examined and NKC-9resin wasselected as the best catalyst. Thus, when NKC-9resin was employed as catalyst, theconversion of acetone reached up to59.5％and the selectivity of triacetoneaminewas63.8％under the optimized reaction conditions.