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The synthesis of derivatives of 3-amino-3-deoxy-L-erythrose by LAH or LAD reduction of the oxime of 1,2-O-isopropylidene α-L -glycero-tetros-3-ulofuranose is described. 相似文献
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γγγ-Trifluorocarbonyl compounds are easily obtained in a good yield by introduction of the 1,1,1-trifluoroethyl moiety (CF3-CH2-) on the -methylene group of a ketone. 相似文献
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Thin films of methylammonium lead halides, CH3NH3PbI3 and CH3NH3PbI3-xClx, were deposited onto symmetrical microstructured electrode arrays of gold or platinum on Si/SiO2 wafers. Polarization studies were carried out on perovskite films under vacuum in the dark. For poling, a constant voltage was applied to the samples while the temperature was cycled between 295 K and 4 K. The measured current densities depending on the temperature showed distinct characteristics relating strongly to the crystal phase and the dielectric properties of the perovskite films. Voltage sweeps were carried out at different scan rates at specific temperature intervals after poling. The polarization of the films due to the migration of iodide vacancies in direction of the blocking perovskite/metal interface was frozen almost up to room temperature. Charge carriers were only able to cross the blocking barrier and contribute to the current where the ions have accumulated during poling. All J-V curves showed hysteresis: inverted and regular hysteresis at room temperature and below, respectively. Inverted hysteresis originates from the slow accumulation of ions at the blocking barrier, while regular hysteresis arises from a distortion in the adjacent crystals which will be discussed. 相似文献
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Recent computational studies on the addition of ammonia (NH3) to the Al3O3- cluster anion [A. Guevara-Garcia, A. Martinez, and J. V. Ortiz, J. Chem. Phys. 122, 214309 (2005)] have motivated experimental and additional computational studies, reported here. Al3O3- is observed to react with a single NH3 molecule to form the Al3O3NH3- ion in mass spectrometric studies. This is in contrast to similarly performed studies with water, in which the Al3O5H4- product was highly favored. However, the anion PE spectrum of the ammoniated species is very similar to that of Al3O4H2-. The adiabatic electron affinity of Al3O3NH3 is determined to be 2.35(5) eV. Based on comparison between the spectra and calculated electron affinities, it appears that NH3 adds dissociatively to Al3O3-, suggesting that the time for the Al3O3-NH3 complex to either overcome or tunnel through the barrier to proton transfer (which is higher for NH3 than for water) is short relative to the time for collisional cooling in the experiment. 相似文献
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Sonja Stanković Matthias D’hooghe Kourosch Abbaspour Tehrani Norbert De Kimpe 《Tetrahedron letters》2012,53(2):107-110
1-t-Butyl- and 1-(4-methylbenzyl)-3-bromo-3-methylazetidines were prepared from the corresponding N-(2,3-dibromo-2-methylpropylidene)alkylamines and their propensity to undergo nucleophilic substitution at the 3-position by different nucleophiles was assessed, providing a convenient access to novel 3-alkoxy-, 3-aryloxy-, 3-hydroxy-, 3-cyano-, 3-carboxy-, 3-(aminomethyl)- and 3-(hydroxymethyl)azetidines. 相似文献
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The thermal behaviors of clusters [Ag3WS3Br](PPh3)3 and [Cu3WS3Br](PPh3)3 (PPh3=triphenyl phosphine) in a nitrogen atmosphere were studied under the non-isothermal conditions by simultaneous TG-DTG-DSC and EDS techniques. The results showed that the evolution of PPh3 generally proceeded before the release of the other moiety in one or two step-mode. The mechanisms, the kinetic and the thermodynamic parameters for decomposition of PPh3 of both clusters were determined and calculated by jointly using several methods, which showed that its evolution was controlled by Avrami-Erofeev equation. The results also showed that there was no new stable phase composed of W-Ag(Cu)-S-Br after release of organic moiety PPh3 and that CVD method was not applicable to their further processing. 相似文献
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3-(3'-乙酰基-5'-芳基-1',3',4'-二氢噁二唑-2'-)色酮的微波促进合成 总被引:2,自引:0,他引:2
将微波应用于促进有机合成是近年来兴起的新技术,已受到极大注意,我们采用简单的微波反应装置,成功地合成了3-杂环基取代的色酮,杂环基取代的色酮因其显著的生理活性,而成为近年来的研究特点,以3-甲酰基色酮为原料,与芳酰肼反应得到相应的芳酰腙,再用乙酸酐关环,合成了一系列3位为1,3,4-二氢恶二唑基取代的色酮(3),为在合适的母体上引入杂环提供了一系新思路,合成路线如下。 相似文献
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E. Träbert N. Reistad I. Martinson R. Hutton 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1989,11(3):207-211
In the EUV spectrum of foil-excited 24 MeV Ni ions the decays of the 3s 3p 3 and 3s 2 3p 3d levels to the 3s 2 3p 2 levels of the ground configuration have been observed. For most of the levels decay curves have been obtained. The lifetime results compare well with predictions from semi-empirically scaled HXR calculations. Some problems with cascade repopulations will be discussed. 相似文献
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The title reaction has been investigated in a diaphragmless shock tube by laser schlieren densitometry over the temperature range 1163-1629 K and pressures of 60, 120, and 240 Torr. Methyl radicals were produced by dissociation of 2,3-butanedione in the presence of an excess of dimethyl ether. Rate coefficients for CH(3) + CH(3)OCH(3) were obtained from simulations of the experimental data yielding the following expression which is valid over the range 1100-1700 K: k = (10.19 ± 3.0)T(3.78)?exp((-4878/T)) cm(3) mol(-1)s(-1). The experimental results are in good agreement with estimates by Curran and co-workers [Fischer, S. L.; Dryer, F. L.; Curran, H. J. Int. J. Chem. Kinet.2000, 32 (12), 713-740. Curran, H. J.; Fischer, S. L.; Dryer, F. L. Int. J. Chem. Kinet.2000, 32 (12), 741-759] but about a factor of 2.6 lower than those of Zhao et al. [Zhao, Z.; Chaos, M.; Kazakov, A.; Dryer, F. L. Int. J. Chem. Kinet.2008, 40 (1), 1-18]. 相似文献
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N. A. Anisimova V. M. Berestovitskaya G. A. Berkova N. G. Makarova 《Russian Journal of Organic Chemistry》2007,43(5):652-655
Reactions of 3-nitro-and 3-bromo-3-nitroacrylates with sodium azide proceed as 1,3-dipolar cycloaddition and lead to the formation of triazolyl-and nitrotriazolylcarboxylates, and also of azido-and azidonitropropenoates. 相似文献
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This paper reports for the first time that under ammonia atmosphere, ammonia borane (AB) reversibly absorbs up to at least 6 equiv of NH(3), forming liquid AB(NH(3))(n) (n = 1-6) complexes at 0 °C. Reasonable structures for AB(NH(3))(n) were identified via density functional theory calculations, which indicate that the strong classical hydrogen bond formed between the lone pair of NH(3) and the -NH(3) of AB is the driving force for the absorption of ammonia by AB. By use of the van't Hoff equation, the enthalpy change (ΔH) for AB to absorb one NH(3) was determined to be -2.24 kcal/mol, which is in good agreement with the theoretical calculations. Other organic amines were screened to further confirm the role of the N lone pair; only 1,4-diazabicyclo[2.2.2]octane (DABCO) formed a stable adduct, which X-ray structural analysis showed was the DABCO-BH(3) species. Finally, Raman spectra of AB(NH(3))(n) were collected, and its unique spectral features are also discussed. 相似文献