tThe acid-catalyzed condensation of acetone and ammonia to directly produce 2,2,6,6-tetramethy-4-piperidone (triacetonamine) was studied under both homogeneous and heterogeneous catalysis. Theselectivity to the desired product was affected by the presence of a complex reaction network involvingseveral kinetically parallel and consecutive reactions, leading to by-products such as diacetonealcohol,diacetoneamine, mesityl oxide, acetonine, and 2,2,4,6-tetramethyl-2,5-dihydropyridine. The latter wasthe most undesired by-product, since its formation was irreversible. Key elements in achieving high selec-tivity in the direct synthesis of triacetonamine were the molar feed ratio between acetone and ammonia,and the amount of water in the reaction medium; in fact, water was found to play an important rolein the transformation of the intermediate acetonine into triacetonamine. Compared with homogeneouscatalysis, the selectivity achieved by the use of the heterogeneous H-Y zeolites was controlled by meansof a proper selection of the zeolite features. In fact, the use of a highly hydrophilic H-Y zeolite made it pos-sible to achieve the same selectivity as that obtained under homogeneous catalysis conditions, with theadditional advantage of using an easily separable and reusable catalyst, which showed no deactivation.

Towards a more sustainable production of triacetoneamine with heterogeneous catalysis

GLIOZZI, GHERARDO;RIGHI, PAOLO;CAVANI, FABRIZIO
2014

Abstract

tThe acid-catalyzed condensation of acetone and ammonia to directly produce 2,2,6,6-tetramethy-4-piperidone (triacetonamine) was studied under both homogeneous and heterogeneous catalysis. Theselectivity to the desired product was affected by the presence of a complex reaction network involvingseveral kinetically parallel and consecutive reactions, leading to by-products such as diacetonealcohol,diacetoneamine, mesityl oxide, acetonine, and 2,2,4,6-tetramethyl-2,5-dihydropyridine. The latter wasthe most undesired by-product, since its formation was irreversible. Key elements in achieving high selec-tivity in the direct synthesis of triacetonamine were the molar feed ratio between acetone and ammonia,and the amount of water in the reaction medium; in fact, water was found to play an important rolein the transformation of the intermediate acetonine into triacetonamine. Compared with homogeneouscatalysis, the selectivity achieved by the use of the heterogeneous H-Y zeolites was controlled by meansof a proper selection of the zeolite features. In fact, the use of a highly hydrophilic H-Y zeolite made it pos-sible to achieve the same selectivity as that obtained under homogeneous catalysis conditions, with theadditional advantage of using an easily separable and reusable catalyst, which showed no deactivation.
2014
Gliozzi, G.; Frattini, L.; Righi, P.; Cavani, F.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/519801
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