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排序方式: 共有123条查询结果,搜索用时 62 毫秒
1.
Ten bis(4-aryloxy-3-nitrophenyl) sulfones were synthesized via a phase-transfer catalyzed, nucleophilic displacement reaction involving phenoxides and bis(4-chloro-3-nitrophenyl) sulfone. 相似文献
2.
Kevin Tienda Zhenning Yu Fadwa Constandinidis Andria Fortney William A. Feld Eric Fossum 《Journal of polymer science. Part A, Polymer chemistry》2011,49(13):2908-2915
A series of poly(arylene ether)s, (PAEs), carrying a pendant diphenyl phosphoryl group were prepared via the nucleophilic aromatic substitution (NAS) reactions of 3,5‐difluorotriphenylphosphine oxide, 6 . The difluoro monomer 6 was synthesized via two‐step reaction sequence and subsequently characterized by 1H, 13C, 19F, and 31P NMR spectroscopy, GC/MS, and elemental analysis. The reactivity of the electrophilic sites in 6 , activated by only a diphenylphosphoryl group located in the meta‐position, in 6 was probed via NMR spectroscopy and model reactions and was determined to be sufficient to undergo typical NAS reactions. High molecular weight, amorphous, organic soluble poly(arylene ether)s, bearing a pendant diphenylphosphoryl group, were prepared via the reaction of 6 with a variety of bis‐phenols under typical NAS conditions. The poly(arylene ether)s were characterized for structure via the use of 1H, 13C, and 31P NMR spectroscopy while their thermal properties were evaluated using DSC and TGA analysis. The glass transition temperatures (Tg) of the synthesized PAEs ranged from 143 to 175 °C, while their 5% weight loss temperatures ranged from 467 to 510 °C under nitrogen and from 470 to 526 °C in air. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
3.
Keng Lung Lee Joey Feld Dr. Paul Hume Prof. Tilo Söhnel Dr. Erin Leitao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(2):815-824
A series of ammonium monosubstituted H-phosphonate salts were synthesized by combining H-phosphonate diesters with amines in the absence of solvent at 80 °C. Variation of the ester substituent and amine produced a range of ionic liquids with low melting points. The products and by-products were analyzed by spectroscopic and spectrometric techniques in order to get a better mechanistic picture of the dealkylation and formal dearylation observed. For dialkyl H-phosphonate diesters, (RO)2P(O)H (R=alkyl), the reaction proceeds via direct dealkylation with the reactivity increasing in the order R=iPr<Et<Me corresponding to DFT calculated activation enthalpies of 22.6, 20.8, and 17.9 kcal mol−1. For the diphenyl H-phosphonate diesters, (PhO)2P(O)H, the dearylation was found to proceed via phenol-assisted formation of a 5-coordinate intermediate, (PhO)3PH(OH), from which P(OPh)3 and water were eliminated. The presence of an equivalent of water then facilitated the formation of P(OH)2OPh and the amine, R'NH2, subsequently abstracted a proton from it to yield [(PhO)PH(O)O]-[R'NH3]+. 相似文献
4.
Ohne Zusammenfassung 相似文献
5.
A. Kurtenacker A. Fritsch F. Raschig E. H. Riesenfeld G. W. Feld und R. Willst?tter 《Fresenius' Journal of Analytical Chemistry》1925,67(1-2):64-67
Ohne Zusammenfassung 相似文献
6.
7.
F. Krauss E. H. Riesenfeld F. Feld J. Kendall A. W. Davidson und W. Böttger 《Fresenius' Journal of Analytical Chemistry》1926,69(4):178-179
Ohne Zusammenfassung 相似文献
8.
Laser-induced nuclear orientation has been used to make sub-Doppler-resolution measurements of a nuclear isomer85mRb that has a lifetime of only a microsecond. The technique succeeds because the sampled atoms remove themselves before equilibrating.
This paper describes two cases in which pre-equilibrium removal of atoms can prevent thermal equilibrium from obscuring information
about the weak interaction that is present in the velocity profile of atoms as they recoil following beta decay. It should
be possible to measure electron-antineutrino angular correlations in the beta decay of85Kr, and to look for beta decay of tritium into an atomic bound state of3He-a fundamental effect predicted by weak interaction theory but never observed. 相似文献
9.
Fred R. Beyette Patrick J. Stanko Eric M. Hayes Rick D. Snyder Stewart A. Feld Pericles A. Mitkas Carl Wilmsen 《Optical Review》1996,3(6):A373-A375
The architecture of an optoelectronic recirculating sorter based on the hybrid integration of CMOS logic circuitry, silicon detector/receivers and vertical cavity surface emitting lasers is presented along with the demonstration of the system. 相似文献
10.
CM Thaker S Rayaprol Krushna Mavani DS Rana MS Sahasrabudhe SI Patil DG Kuberkar 《Pramana》2002,58(5-6):1035-1039
The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO3 perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good
example of these properties is (La1−2x
Pr
x
Ca
x
)MnO3 (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T
c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using
X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for
understanding the structural, transport and magnetic properties are discussed in detail. 相似文献