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1.
Fluoride effect on the palladium–phenanthroline catalyzed carbonylation of nitroarenes to carbamates
Michela Gasperini Fabio Ragaini Sergio Cenini Emma Gallo Simone Fantauzzi 《应用有机金属化学》2007,21(9):782-787
Fluorides promote the palladium–phenanthroline catalyzed carbonylation of nitroarenes to carbamates. The effect is more evident on the rate of the reaction at short reaction times, but a positive effect on selectivity is also observed under certain conditions. The effect is observed even under conditions under which chloride inhibits the reaction. Tetraethylammonium is a better countercation than sodium. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
2.
In photochemical vapor deposition of aluminum film on silicon using dimethylaluminum hydride, (CH3)2AlH, a surface reaction dominated below a (CH3)2AlH pressure of 0.3 m Torr at 200°C, which was induced only with the 160 nm band emitted from a deuterium lamp. A gas-phase reaction occurred above 0.3 mTorr at 200°C, which could be induced by both 160 nm and 240 nm emission bands from the lamp. To distinguish between surface ad gas-phase reactions, a thickness profile was used. At 240°C the surface reaction could be induced even by the 240 nm band, while the deposits formed under illumination of the two bands were thinner than those obtained with only the 240 nm band, indicating occurrence of vacuum ultraviolet (VUV)-enhanced desorption. The mechanism responsible for the observed wavelength dependence in unclear. The electrical resistivity of the films deposited at 200°C was 4.5 μΩ cm, which did not change with wavelength. 相似文献
3.
S.V. Kini 《Tetrahedron letters》2004,45(21):4171-4173
Hofmann degradation of 1-arylmethyl-1,2,3,4-tetrahydro-2,2-dimethylisoquinolinium iodides with methanolic KOH gave stilbene derivatives, for example, (E)-N-2{2-[2-(phenyl)ethenyl]-4,5-dimethoxyphenyl}ethyl-N,N-dimethylamine. Photochemical electrocyclization of these stilbenes afforded the corresponding phenanthrene alkaloids/phenanthrene derivatives. 相似文献
4.
Tandem intramolecular silylformylation-allyl(crotyl)silylation reactions have been developed that allow the highly efficient synthesis of polyketide fragments. The substrates are subjected to Rh(I)-catalyzed silylformylation to afford β-(diallyl)silyl aldehydes which undergo spontaneous uncatalyzed allylsilylation. This unusual spontaneous allylsilylation reaction is driven by strain release Lewis acidity, which arises from the ∼95° O-Si-C bond angle in the oxasilacyclopentane product of the silylformylation reaction. The methodology has been developed both for alkene and alkyne substrates, may be used to establish as many as three stereocenters, and has been shown to be amenable to use in an iterative fashion. 相似文献
5.
A. L. Lapidus S. D. Pirozhkov A. R. Tumanova T. G. Koksharova N. V. Volkova V. A. Bakulev V. S. Mokrushin 《Russian Chemical Bulletin》1992,41(1):178-180
A new method has been developed for the synthesis of the ethyl ester of the mononitrile of malonic acid by the carbonylation of benzenesulfonyloxyacetonitrile in absolute ethanol in the presence of cobalt carbonyl. The yield of the desired product was 30% with 60–90% conversion of the starting compound. The effects of temperature, pressure, and reaction time were studied.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. S. M. Kirov Urals Polytechnical Institute, Ekaterinburg. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 215–216, January, 1992. 相似文献
6.
一种甲醇直接气相羰基化新催化剂 总被引:12,自引:0,他引:12
本世纪70年代Monsanto公司成功开发了甲醇液相羰化RhI催化体系,使甲醇羰化生产醋酸成为重要的工业过程.然而,由于此工艺产物与催化剂分离复杂、铑资源紧缺以及体系中还必须加大量的碘甲烷(或氢碘酸)作促进剂,设备腐蚀严重.80年代以来,甲醇气相羰... 相似文献
7.
1,2-二乙炔基四苯基乙硅烷与1,2-二乙炔基四甲基乙硅烷在催化剂铑(Ⅰ)络合物[氯化三-(三苯基膦)铑]的作用下得到一种新的含硅共聚物。实验证明此共聚物的主链是有规交替结构。研究了固体薄膜及其溶液的光解作用,并测定了SbF_5蒸气处理后的共聚物薄膜的导电性。 相似文献
8.
A novel type of heterogenized CuCl2 catalysts was designed for the oxidative carbonylation of methanol to dimethyl carbonate (DMC) taking account of the plausible reaction mechanism and intermediates. To prevent severe corrosion of the reaction equipment materials due to Cl– while keeping the catalytic activity of the homogeneous CuCl2 catalyst, we adopted, as supports (or ligands) of CuCl2, four polymers, bearing a 2,2-bipyridine (bpy) or pyridine (py) unit, namely, poly(2,2-bipyridine-5,5-diyl) (Pbpy), poly(pyridine-2,5-diyl) (Ppy), poly(N,N-bisphenylene-2,2-bipyridine-4,4-dicarboxylic amide) (Bpya), and poly(4-methyl-4-vinyl-2,2-bipyridine) (Pvbpy), together with one chelate compound, 8-quinolinol. The catalytic activity, stability of heterogenized CuCl2 and their corrosivities to stainless steels were examined in the liquid-phase reaction of the oxidative carbonylation of methanol. These polymer-supported catalysts showed considerable catalytic activity and stability for the DMC synthesis. In particular, the Pbpy-CuCl2 and Ppy-CuCl2 catalysts exhibited high DMC yields and selectivity comparable to those of the homogeneous CuCl2 catalyst. This high activity appears to be associated with the presence of the -conjugated system in the polymers, which affect the redox reactions of Cu involved in the catalytic reaction. All of the polymer-supported CuCl2 catalysts could be easily recycled after filtration, and the initial catalytic activity was maintained after three times of use. The corrosive characters of the catalysts were closely related to CuCl2 leaching from the supports, which reflects the ability of supports to coordinate Cu. These experimental results suggest that both the electronic structure and the coordination ability of the polymer supports are key factors for the development of an effective catalytic system. 相似文献
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