共查询到20条相似文献,搜索用时 15 毫秒
1.
N.C. Marziano L. Ronchin C. Tortato A. Vavasori M. Bortoluzzi 《Journal of molecular catalysis. A, Chemical》2008,290(1-2):79-87
The influence of some transition metal oxide promoters in the catalyzed Beckmann rearrangement of cyclohexanone oxime was studied by preparing several heterogeneous H2SO4/M/SiO2 catalysts using SiO2 as support and H2SO4 as acid source. A definite effect of each metal has been observed and the best results have been obtained with Cr-, Zr- and Zn-oxides based promoter, which have shown an improved selectivity towards -caprolactam formation if compared to the H2SO4/SiO2 catalytic system. Moreover, the influence of some organic promoters on the reaction pathway was investigated. Acetic and trifluoroacetic anhydrides gave the best results, even if only the latter allowed the rearrangement even without solid acid catalysts. The transacetylation of the cyclohexanone oxime by using the acetyl caprolactam, which is the product of rearrangement of the acetyl cyclohexanone oxime, was studied for developing a step wise catalytic cycle. Finally, some preliminary results on a homogeneous organic catalyzed process are reported. 相似文献
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A novel catalyst, boria supported on titania-zirconia mixed oxide, exhibits very high catalytic activity and selectivity in vapor-phase Beckmann rearrangement of cyclohexanone oxime to e-caprolactam. It gives 99.7% oxime conversion and 97.0% lactam selectivity at 300°C. 相似文献
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Yongjie Zhang Yaquan Wang Yifeng Bu Li Wang Zhentao Mi Wei Wu Enze Min Songbao Fu Zehua Zhu Fei He Sen Han 《Reaction Kinetics and Catalysis Letters》2007,90(2):365-372
A series of Ti-Hβ zeolites were synthesized by liquid-solid isomorphous substitution. Hβ and Ti-Hβ zeolites were characterized
by BET, XPS, IR, etc., and studied in the vapor phase Beckmann rearrangement of cyclohexanone oxime. In comparison with pure
Hβ, the incorporation of Ti in the Hβ framework leads to larger BET surface area and weaker Br?nsted acid sites. The incorporation
of Ti in the Hβ framework increases the conversion of cyclohexanone oxime and its stability. It is inferred that for the catalysts
having the structure of a β zeolite, the suitable acid sites for the vapor phase Beckman rearrangement might be the weak Br?nsted
acid sites. 相似文献
4.
Bi(OTf)3 and SiO2-Bi(OTf)3 are found to effectively catalyze the Ferrier rearrangement of tri-O-acetyl glycals with different alcohols providing an effective route to 2,3-unsaturated O-glycosides with good anomeric selectivity and good to excellent yields after short reaction times. 相似文献
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Dongsen Mao Guanzhong Lu Qingling Chen 《Journal of molecular catalysis. A, Chemical》2005,240(1-2):164-171
The deactivation and regeneration of B2O3/TiO2-ZrO2 catalyst for the vapor phase Beckmann rearrangement of cyclohexanone oxime to -caprolactam were studied. The fresh, deactivated and regenerated catalysts were characterized by using adsorption of nitrogen, X-ray diffraction (XRD), thermogravimetry (TG) and NH3-temperature-programmed desorption (NH3-TPD) techniques. The crystal structure and pore size distribution of the catalyst were retained after reaction, but the number of acid sites decreased significantly. There was a relationship between the amount of coke deposited on the catalyst and the decline in catalytic activity. These results suggest that the coke deposition on the surface of catalyst is mainly responsible for the catalyst deactivation. The catalytic activity can be recovered completely after calcining the deactivated catalyst in air flow at 600 °C for 8 h. 相似文献
8.
Zhen Li Chengtao Fang Yannan Zheng Guanyinsheng Qiu Xiaofang Li Hongwei Zhou 《Tetrahedron letters》2018,59(44):3934-3937
A switchable synthesis route is developed for benzo[d]oxazole derivatives and (2-hydroxylaryl)benzamide from 2-hydroxylbenzeneketoxime using organomolecules (BOP-Cl, and CNC) and Lewis acid cocatalyzed Beckmann rearrangement (BR) reaction. Further, this reaction is switched using different organocatalysts. 相似文献
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Weiss ME Fischer DF Xin ZQ Jautze S Schweizer WB Peters R 《Angewandte Chemie (International ed. in English)》2006,45(34):5694-5698
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G. N. Dorofeenko G. P. Safaryan T. I. Polyakova 《Chemistry of Heterocyclic Compounds》1972,8(11):1318-1320
2-Aryl-3,4,5,6-bis(trimethylene)pyrylium perchlorates were obtained by acylation of cyclopentylidenecyclopentanone with aromatic acid chlorides in the presence of anhydrous aluminum chloride with subsequent treatment with 70% perchloric acid. The synthesized salts were converted to the corresponding pyridine bases.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1461–1463, November, 1972. 相似文献
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Antonio García Martínez Santiago de la Moya Cerero Beatriz Lora Maroto 《Tetrahedron》2004,60(42):9447-9451
The competitive pathway timing for the previously described unexpected bromo-assisted Beckmann fragmentation of 7-anti-bromo-3,3-dimethyl-2-oxonorbornane-1-carboxamide has been investigated. It is concluded that this unusual process is activated by a synergic effect exerted by both the C(7)-anti-bromo and C(1)-aminocarbonyl groups. The effect consists in a specific intramolecular activation of the bromo-assistance by the bridgehead aminocarbonyl group. 相似文献
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J. Nyitrai J. Fetter Gy. Hornyák K. Zauer K. Lempert I. Koczka I. Sági Cs. Rétháti 《Tetrahedron》1978,34(7):1031-1035
5,6-Dihydro-2H-1,3-thiazin-4(3H)-ones 2–10 related to the natural antituberculytic Mycobacidine 1, have been synthesised. Some of the compounds of types 2,3 and 5 proved highly active in vitro against Mycobacterium tuberculosis typ. humanus (H37Rv), but the in vitro activities are diminished or suspended in the presence of biotine. 相似文献
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Choji Kashima Akira Katoh Nobutoshi Yoshiwara Yoshimori Omote 《Journal of heterocyclic chemistry》1981,18(8):1595-1596
1-Aryl-3,4,5,6-tetrahydro-2-(1H)pyrimidinones (I) underwent reductive ring opening reaction with lithium aluminum hydride to afford N-aryl-2,4-diaminopentanes (II) in good yields. On the other hand, 3,4,5,6-tetrahydro-3,4,6-trimethyl-1-phenyl-2-(1H)-pyrimidinone (V) gave only cyclic diamine, 3,4,6-trimethyl-1-phenylhexahydropyrimidine (VI), in 60% yield. 相似文献
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Mohammad Ali Zolfigol Vahid Khakyzadeh Ahmad Reza Moosavi-Zare Abdolkarim Zare Seyedeh Bahareh Azimi Zhila Asgari Alireza Hasaninejad 《Comptes Rendus Chimie》2012,15(8):719-736
In this work, some novel sulfonic acid functionalized imidazolium salts (SAFIS), as a new category of ionic liquids, are synthesized by eco-friendly and simple procedures, and used as highly efficient and reusable catalysts to promote the following one-pot multicomponent organic transformations under solvent-free conditions: (i) the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes from β-naphthol (2 eq.) and arylaldehydes (1 eq.), (ii) the preparation of tetrahydrobenzo[a]xanthene-11-ones from β-naphthol, arylaldehydes and dimedone, and (iii) the synthesis of 1,8-dioxo-octahydroxanthenes from dimedone (2 eq.) and aromatic aldehydes (1 eq.). Environmentally benign, simple methodologies, easy workup procedure, clean reaction, short reaction time, high yield and easy preparation of the catalysts are some advantages of this work. 相似文献
19.
Phosphonium ionic liquids exchanged with bicarbonate and methylcarbonate anions (CILs) exhibit catalytic performances comparable to those of sterically hindered (non nucleophilic) organosuperbases such as DBU. At 25-50 °C, under solventless conditions, CILs efficiently catalyze the Henry addition of different aldehydes and ketones to nitroalkanes: not only they allow the selective formation of nitroaldols but they unlock a novel high-yielding access to dinitromethyl derivatives of ketones. 相似文献
20.
John S. Kiely Edgardo Laborde Lawrence E. Lesheski Ruth A. Bucsh 《Journal of heterocyclic chemistry》1991,28(6):1581-1585
A series of 1-cyclopropyl-1,4-dihydro-4-oxoquinolines was prepared in which the C-7 position is substituted with a vinyl, a 1-cyclopentenyl, or a 1,2,3,6-tetrahydro-4-pyridinyl group. These quinolones were synthesized via a palladium-catalyzed cross coupling of a 7-quinolyltriflate with an appropriately functionalized vinylstannane. 相似文献