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41.
Heng-dao Quan Hui-e Yang Masanori Tamura Akira Sekiya 《Journal of fluorine chemistry》2004,125(7):1169-1172
A novel fluorination reagent and catalyst, SbF5/PAF (porous aluminum fluoride), was prepared by impregnating SbCl5 into PAF and then treating with anhydrous hydrogen fluoride. The prepared reagent had an excellent catalytic activity in halogen-exchange, and also improved the properties of SbF5, such as hydroscopicity, corrosion, and toxicity. SbF5/PAF was successfully used in organic synthesis as a fluorinating reagent, and a fixed bed catalyst for F/Cl exchange. 相似文献
42.
Simons electrochemical fluorination (ECF) of 1,4-dimethyl-1,4-homopiperazine, methyl 4-ethylhomopiperazin-1-ylacetate and 1,4-bis(methoxycarbonylmethyl)-1,4-homopiperazine was studied. For comparison, ECF of three piperazines with a N-(methoxycarbonylmethyl) group(s) was also studied. ECF of 1,4-dimethyl-1,4-homopiperazine gave a low yield of corresponding perfluoro(1,4-dimethyl-1,4-homopiperazine) together with perfluoro(2,6-diaza-2,6-dimethylheptane) as the major product. Corresponding perfluoro(homopiperazines) with mono- and/or di-(fluorocarbonyldifluoromethyl) groups [CF2C(O)F] at the 1- and/or 4-position were formed in low yields from methyl 4-ethylhomopiperazin-1-ylacetate and 1,4-bis(methoxycarbonylmethyl)-1,4-homopiperazine, respectively. These new seven-membered perfluoro(1,4-dialkyl-1,4-homopiperazines) were accompanied by the formation of mono- and/or di-basic linear perfluoroacid fluorides resulting from the CC bond scission at the 2- and 3-positions of the ring. From mono- and/or di-N-(methoxycarbonylmethyl)-substituted piperazines, corresponding perfluoropeperazines having the acid fluoride group(s) were formed in low yields. 相似文献
43.
Evaluating the acute toxic effects of drugs or toxins is based mainly on studies which require the use of light microscopy. Recently, the effects of such substances on biological membranes, such as the nasal membrane, has been studied using the traditional Ussing chambers, which make it possible to study the transepithelial flux of drugs across membranes and to measure some bioelectrical parameters. A model is described, with which the changes in the membrane permeability, for sodium, potassium and chlorine, can be calculated directly, based on values obtained from the Ussing chamber system. Also, an experiment is described for evaluating the toxic effects of the cholera toxin B subunit, by measuring these changes in isolated rabbit nasal mucosa. 相似文献
44.
Densities and sound velocities of binary mixtures of cyclohexanone, 2-butanone, 1,4-dioxane and 1,2-dimethoxyethane were measured
at 298.15 K and also the densities at 303.15 K. Excess volumes were determined from densities. Isentropic compressibilities
were determined from densities and sound velocities, and excess thermal expansion factors were determined from excess volumes
of two temperatures. Excess isothermal compressibilities and excess isochoric heat capacities were then estimated using excess
isobaric heat capacities previously reported. Excess volumes and excess isentropic and isothermal compressibilities were negative
except for cyclohexanone+1,4-dioxane system.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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48.
Kano K Kitagishi H Tamura S Yamada A 《Journal of the American Chemical Society》2004,126(46):15202-15210
5,10,15,20-Tetrakis(4-sulfonatophenyl)porphinato iron(III) (Fe(III)TPPS) forms a very stable 1:2 complex with heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TMe-beta-CD), whose iron(III) center is located at a hydrophobic cleft formed by two face-to-face TMe-beta-CD molecules. Various inorganic anions (X(-)) such as F(-), Cl(-), Br(-), I(-), N(3)(-), and SCN(-) coordinate to Fe(III)TPPS(TMe-beta-CD)(2) to form five-coordinate high-spin Fe(III)TPPS(X)(TMe-beta-CD)(2), while no coordination occurs with ClO(4)(-), H(2)PO(4)(-), NO(3)(-), and HSO(4)(-). Except for F(-), none of the anions investigated coordinate to Fe(III)TPPS in the absence of TMe-beta-CD due to extensive hydration to the anions as well as to Fe(III)TPPS. The present system shows a high selectivity toward the N(3)(-) anion. The thermodynamics suggests that Lewis basicity, hydrophilicity, and shape of an X(-) anion are the main factors to determine the stability of the Fe(III)TPPS(X)(TMe-beta-CD)(2) complex. 相似文献
49.
The mass spectra obtained from ions having excess kinetic energy (named the excess kinetic energy mass spectra) formed by electron impact of several aliphatic amines have been studied. Comparison with the excess kinetic energy mass spectra of the analogous alcohols shows many similarities. For example, the intensity of the [CH2OH]+ ion of an aminoalcohol is about the same as the intensity of the [CH2NH2]+ ion. The excess kinetic energy mass spectra give useful information about the presence or absence of various functional groups, such as CH2NH2, CH2OH, CH3CHNH2 and alkyl groups, and also about rearrangements. The fragmentation mechanisms are straightforward and applicable to a variety of classes of compounds. The molecular weight dependence of excess kinetic energy mass spectra is described. 相似文献
50.
Kitazaki T Tasaka A Tamura N Matsushita Y Hosono H Hayashi R Okonogi K Itoh K 《Chemical & pharmaceutical bulletin》1999,47(3):351-359
New optically active antifungal azoles, 1-[(1R,2R)-2-(2,4-difluoro- and 2-fluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-yl)propyl ]-3-(4- substituted phenyl)-2(1H,3H)-imidazolones (1,2) and 2-imidazolidinones (3,4), were prepared in a stereocontrolled manner from (1S)-1-[(2R)-2-(2,4- difluoro- and 2-fluorophenyl)-2-oxiranyl]ethanols (15, 16). Compounds 1-4 showed potent antifungal activity against Candida albicans in vitro and in vivo, as well as a broad antifungal spectrum for various fungi in vitro. Furthermore, the imidazolidinones, 3b--e and 4d, e, were found to exert extremely strong growth-inhibitory activity against Aspergillus fumigatus. 相似文献