- Towards a more sustainable production of triacetoneamine with heterogeneous catalysis
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The 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. The selectivity to the desired product was affected by the presence of a complex reaction network involving several 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 was the most undesired by-product, since its formation was irreversible. Key elements in achieving high selectivity 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 role in the transformation of the intermediate acetonine into triacetonamine. Compared with homogeneous catalysis, the selectivity achieved by the use of the heterogeneous H-Y zeolites was controlled by means of a proper selection of the zeolite features. In fact, the use of a highly hydrophilic H-Y zeolite made it possible to achieve the same selectivity as that obtained under homogeneous catalysis conditions, with the additional advantage of using an easily separable and reusable catalyst, which showed no deactivation.
- Gliozzi, Gherardo,Frattini, Lucia,Righi, Paolo,Cavani, Fabrizio
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- Synthesis of the first complex with acetonine as ligand: The first crystal structure of an acetonine derivative
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The complex [Au(acetonine)2]ClO4 (3·ClO4) (acetonine = 2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropydrimidine) is obtained by bubbling NH3 through an acetone solution containing equimolar amounts of NaClO4 and [AuCl(tht)] (tht = tetrahydrothiophene); the crystal structure of 3·ClO4 was determined by X-ray crystallography.
- Vicente, Jose,Chicote, Maria Teresa,Guerrero, Rita,Ramirez De Arellano, M. Carmen
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- HETEROGENEOUS CATALYZED PROCESS FOR THE PRODUCTION OF 2,2,6,6-TETRAMETHYL-4-PIPERIDONE
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The present invention relates to a process for the production of 2,2,6,6-tetramethyl-4-piperidone particularly comprising (i) providing a reactor containing a catalyst comprising a zeolitic material having a framework structure of FAU, wherein the zeolitic material comprises YO2 and X2O3 in its framework structure, wherein Y is a tetravalent element and X is a trivalent element, wherein the zeolitic material has an YO2 to X2O3 molar ratio of 16 to 175; (ii) preparing a reaction mixture comprising acetone and ammonia; (iii) contacting the catalyst in the reactor with the reaction mixture prepared in (ii) at a temperature in the range of from 40 to 250 °C for obtaining a reaction product comprising 2,2,6,6-tetramethyl-4-piperidone; wherein the mixture prepared in (ii) and contacted with the catalyst in (iii) contains less than 10 weight-% of water based on 100 weight-% of the reaction mixture.
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Page/Page column 22
(2020/12/11)
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- Effect of Alkali Treatment of HY Zeolite on Continuous Synthesis of Triacetonamine
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The continuous synthesis of triacetonamine from acetone and ammonia over HY was realized. Meanwhile, alkali-treated HY with different structure and acidities were prepared and examined. The results indicated that the acid sites, especially Br?nsted acid sites, played a vital role on the selectivity of triacetonamine and the conversion of acetone. It was further confirmed by X-ray diffraction (XRD), N2 adsorption and desorption experiments, IR spectra of adsorbed pyridine, and NH3 temperature-programmed desorption. Meanwhile, the generation mechanisms of triacetonamine and impurities were speculated.
- Tian, Jun,Chen, Ligong,Zhang, Chao,Yan, Xilong,Li, Yang
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p. 1377 - 1381
(2015/02/19)
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- Continuous synthesis of triacetonamine over sulfonic acid-functionalized mesoporous silicas
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The continuous synthesis of triacetonamine from acetone and ammonia was realized over sulfonic acid-functionalized mesoporous silicas. These catalysts were characterized by TG, XPS, BET, elemental analysis and acid-base titration. The results indicated th
- Tian, Jun,Chen, Ligong,Zhang, Chao,Yan, Xilong,Li, Yang
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p. 17860 - 17865
(2014/05/06)
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- Oxoammonium Salts. 5. A New Synthesis of Hindered Piperidines Leading to Unsymmetrical TEMPO-Type Nitroxides. Synthesis and Enantioselective Oxidations with Chiral Nitroxides and Chiral Oxoammonium Salts
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A new synthesis of unsymmetrical 2,2,6,6-tetraalkyl-4-piperidones from acetonin (2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine) and several ketones is described.When the ketone was a naturally occurring optically active ketone, the piperidones were optically active.The piperidones were converted to unsymmetrical TEMPO-type nitroxides and chiral nitroxides.The optically active nitroxides were used as catalysts for oxidations or converted to chiral oxoammonium salts.The structures of the chiral compounds were determined by 2D (1)H and (13)C NMR, and the cyclic voltammetric properties of the various nitroxides were measured.Several other pyrrolidine oxoammonium salts were prepared, and both types were used as oxidizing agents.Preliminary results of chiral oxidations are presented.
- Ma, Zhenkun,Huang, Qingtao,Bobbitt, James M.
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p. 4837 - 4843
(2007/10/02)
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- Catalytic carhonylation of acetone oxime at bisoximatodiruthenium complexes: A simple access to anhydrous acetonine. Isolation and molecular structure of [Ru2(CO)5(Me2CNO)2 (Me2CNOH)]
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In the presence of catalytic amounts of [Ru2(CO) 4(Me2CNO)2(Me2CNOH)2](1), a cetone oxime reacts with carbon monoxide to give 2,3,4,5-tetrahydro-2,2,4,4, 6-pentamethylpyrimidine ('a cetonine'), CO2, and NH3. The reaction proceeds presumably via carbonylation of Me2C=NOH to the unstable intermediate Me2C=N-OCHO which undergoes decarboxylation to give the corresponding imine Me2C=NH. The final product is assumed to result from the cyclotrimerisation of Me2C=NH with elimination of NH3. Evidence for the intermediacy of the imine comes from the analogous reaction of acetophenone oxime, PhMeC=NOH, which gives the corresponding imine PhMeC=NH as a stable product. The isolation of the complex [RU2(CO)5(Me2CNO)2(Me 2CNOH)] (2) suggests the carbonylation to take place at the bridging oximato ligand of 1.
- Langenbahn, Meinhard,Stoeckli-Evans, Helen,Suess-Fink, Georg
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p. 549 - 553
(2007/10/02)
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- REACTIONS RETRODIENIQUES-IX. SYNTHESE PAR THERMOLYSE ECLAIR ET ETUDE D'ENAMINES PRIMAIRES INSTABLES
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Etheneamine 1 and its methyl derivatives 2-7 have been synthesized from the adducts 8-14 by a retro-Diels-Alder reaction under flash thermolytic conditions.The primary enamines 1-4 have been identified (IR, (1)H and (13)C NMR in a pure state at -80 deg C; at the same temperature, the enamines 5-7, less stable, are already accompanied by their tautomeric imines 33 or 34.When warmed up to room temperature, the enamines 1-7 lead, following to their substitution, either to nitrogen heterocycles (30, 42) or to acyclic azadienes (35-37, 39, 40).
- Ripoll, J. L.,Lebrun, H.,Thuillier, A.
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p. 2497 - 2504
(2007/10/02)
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- Process for the preparation of 2,2,6,6-tetramethyl-4-oxopiperidine
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2,2,6,6-Tetramethyl-4-oxopiperidine is prepared from 2,2,4,4,6-pentamethyl-2,3,4,5-tetramethylpyrimidine (acetonine) by heating in the presence of acetone, diacetone alcohol or water. These regents may be used in excess or an organic solvent is added. The preferred modification is the heating of acetonine hydrate in an excess of acetone or in an acetone-methanol mixture to about 40° to 65°C for several hours. The use of diacetone alcohol permits higher reaction temperatures leading to shorter reaction times.
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