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排序方式: 共有115条查询结果,搜索用时 15 毫秒
81.
The effect of heterogeneous solvent systems on sonochemical reactions: accelerated degradation of alkyl thiols in emulsion 总被引:1,自引:0,他引:1
Sonochemical reactions of alkyl and aryl thiols in water–organic mixed solvent systems were kinetically investigated. The reaction in the liquid–liquid interface apparently depends on the polarities, surface activities, vapor pressures and hydrophobicities of organic solvents and thiols. Interestingly, the rate jump in sonochemical disappearance of alkyl thiols was observed under emulsified conditions. 相似文献
82.
Takahide Nishiyama Fumihiro Endo Hiroko Eguchi Tatsuro Nakagama Nobuko Seino Masaki Shinoda Takuya Shimosaka Toshiyuki Hobo Katsumi Uchiyama 《Analytical sciences》2007,23(4):389-393
An ultra-micro sample injector for gas chromatography (GC) was developed. An ink-jet microchip, originally used for industrial recorder, was modified at the edge near to an orifice, and fixed into the GC. In order to evaluate the characteristics of this injector, a sample injector and a thermal conductive detector (TCD) were connected directly, while water was used as the test sample. The volume of the droplet, the interval time and the back-pressure to the ink-jet microchip were investigated. Within the range of 1 - 5 nL volume injected sample, the TCD response according to the amount of the sample volume (the volume of one droplet from the ink-jet microchip was about 1 nL) was obtained. A good reproducibility of the peak area was obtained to be about 1.0% of the RSD value. In order to compare the injection method of the ink-jet chip with that using a micro-syringe, the method using the ink-jet chip could introduce 1/1000 of the amount of the sample and gave reproducible results. 相似文献
83.
Selective 6-endo cyclization of the acyl radicals onto the nitrogen of imine and oxazoline C-N bonds
Tojino M Otsuka N Fukuyama T Matsubara H Ryu I 《Journal of the American Chemical Society》2006,128(24):7712-7713
Acyl radicals generated by the addition of alkyl or vinyl radicals to carbon monoxide cyclized onto the C-N bonds of imines and oxazoline with perfect 6-endo selectivity, driven by a preference for attack at nitrogen. 相似文献
84.
Uji S Terashima T Nishimura M Takahide Y Konoike T Enomoto K Cui H Kobayashi H Kobayashi A Tanaka H Tokumoto M Choi ES Tokumoto T Graf D Brooks JS 《Physical review letters》2006,97(15):157001
Under special conditions, a superconducting state where the order parameter oscillates in real space, the so-called FFLO state, is theoretically predicted to exist near the upper critical field, as first proposed by Fulde and Ferrell, and Larkin and Ovchinnikov. We report systematic measurements of the interlayer resistance in high magnetic fields to 45 T in the two-dimensional magnetic-field-induced organic superconductor lambda-(BETS)2FeCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene. The resistance is found to show characteristic dip structures in the superconducting state. The results are consistent with pinning interactions between the vortices penetrating the insulating layers and the order parameter of the FFLO state. This gives strong evidence for an oscillating order parameter in real space. 相似文献
85.
Iodination of unactivated aliphatic hydrocarbons with iodoform (CHI3) and solid NaOH were greatly accelerated under ultrasonic irradiation. The mechanism of the sonochemical acceleration was studied. 相似文献
86.
Kimura T Harada H Ando T Fujita M Levêque JM Luche JL 《Chemical communications (Cambridge, England)》2002,(11):1174-1175
Among the sonolysis products of acetic acid, oxidizing intermediates can play a direct role in reactions run in this solvent, illustrating the fact that organic sonochemistry can originate in organic solvents as aqueous sonochemistry can in water. 相似文献
87.
The samarium(II) iodide mediated reaction of N,N-dibenzyl-protected (S)-alpha-amino aldehydes with (1S,2R)-N-methylephedrinyl acrylate gave the (4R,1'S)-gamma-(aminoalkyl)-gamma-butyrolactones in good yields with high diastereoselectivities (up to 80% de); (4R,1'S)-gamma-amino-(2-phenylethyl)-gamma-butyrolactone (6a), which should be a potent precursor for gamma-secretase inhibitors, was obtained with high de value. 相似文献
88.
Asaumi T Matsuo T Fukuyama T Ie Y Kakiuchi F Chatani N 《The Journal of organic chemistry》2004,69(13):4433-4440
The direct carbonylation of C-H bonds in the benzene ring of N-phenylpyrazoles via catalysis by ruthenium or rhodium complexes is described. The reaction of N-phenylpyrazoles with carbon monoxide and ethylene in the presence of Ru(3)(CO)(12) or Rh(4)(CO)(12) resulted in the site-selective carbonylation of the ortho C-H bonds in the benzene ring to give the corresponding ethyl ketones. A variety of functional groups on the benzene ring can be tolerated. N-Phenylpyrazoles have higher reactivities than would be expected, based on the pK(a) values of the conjugate acid of pyrazole. The choice of solvent for this reaction is significant, and N, N-dimethylacetamide (DMA) gives the best result. 相似文献
89.
Tojino M Otsuka N Fukuyama T Matsubara H Schiesser CH Kuriyama H Miyazato H Minakata S Komatsu M Ryu I 《Organic & biomolecular chemistry》2003,1(23):4262-4267
Free-radical mediated cyclizative carbonylations of azaenynes were carried out using TTMSS as a radical mediator to compare the efficiency and the stereochemistry with those using tributyltin hydride. Using a substrate concentration of 0.1 M, the reactions gave good yields of alpha-silylmethylene lactams having four to seven-membered rings. The observed E-diastereoselectivity of the resulting vinylsilane moiety is in sharp contrast to the Z-selectivity observed during the analogous carbonylation using tributyltin hydride. When hexanethiol was used as the radical mediator, alpha-thiomethylene lactams were formed with E-favoring stereoselectivity again. Ab initio and DFT molecular orbital calculations on the stability of E and Z products were carried out for a set of five-membered methylene lactams bearing SnH3, SiH3, and SMe groups. The distinct thermodynamic preference for the Z-isomer was only predicted for the Sn-bearing lactam. A steric effect due to the bulky (TMS)3Si group is proposed for the E-selectivity observed in the TTMSS-mediated reaction. 相似文献
90.
Rahman AF Bhattacharya S Peng X Kimura T Komatsu N 《Chemical communications (Cambridge, England)》2008,(10):1196-1198
In spite of having small pi-conjugation systems, azulenes show large binding constants (10(4)-10(5)) to C(60) and C(70), which are larger than those of monoporphyrins and alternant aromatic hydrocarbons. 相似文献