Preparation And Separation Of The Derivatives Of Triacetonamine

The separation process of triacetonamine and the preparation and separation of4-amino-2,2,6,6-tetramethylpiperidine together with the preparation of1,2,2,6,6-pentamethylpiperidin-4-one are studied in this paper.The reaction mixture of triacetonamine is separated by a batch column with a sidestream. The purity of triacetonamine distilled is above 99%. The slop cut oftriacetonamine can be reduced and the recovery of triacetonamine can be increased bydistillation process in the batch column with a side stream, so the recycle recovery oftriacetonamine is above 90%.The preparation and separation of 4-amino-2,2,6,6-tetramethylpiperidine aresystematically studied in this paper. The reaction conditions such as the molar ratio ofammonia to triacetonamine, the type and activation of catalyst, the quantity of catalyst,reaction time, are investigated. The yield and selectivity is higher using the binarycatalyst than ternary catalyst and the recycled binary catalyst is much better. Theoptimal conditions for preparation of 4-amino-2,2,6,6-tetramethylpiperidine in ourexperiments are: the molar ratio of ammonia to triacetonamine is 5.25:1, the amountof catalyst is 12% by weight of triacetonamine and the catalyst is recycled binarycatalyst, water as additives by equal weight of triacetonamine, reaction temperature is100℃, and the pressure is 2Mpa. The reaction mixture was separated by distillationin 1 atm and a vacuum condition, and the purity of4-amino-2,2,6,6-tetramethylpiperidine distilled is above 99%. The saturationpressures of 4-amino-2,2,6,6-tetramethyl piperidine and2,2,6,6-tetramethyl-4-piperidinol were predicted by corresponding state with groupcontribution(CSGC) method. The distillation process is simulated by a constant molarflow model, and the simulation results agrees well with that of experiment.The preparation of 1,2,2,6,6-pentamethylpiperidin-4-one is also studied and theprocess is traced by gas chromatography. The yield of 1,2,2,6,6-pentamethylpiperidin-4-one is about 50-60% generally, and the maximum yield is 81% in ourexperiment.