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Hooshang Pirelahi Yahyo Abdoh Manoochehr Tavassoli 《Journal of heterocyclic chemistry》1977,14(2):199-201
The reactions of p-trifluoromethylphenyllithium with 2,4,6-triarylthiopyrylium perehlorates (Ar = Ph, p-CH3OC6H4, p-NMe2C6H4) have been studied. The initially formed thiabenzenes were not slable enough to he isolated and rearranged readily to their corresponding 4-(p-tri-fluoromethylphenyl)-2,4,6-triarylthiopyrans. The instability of the intermediate thiabenzenes reveals that, in contrast to the stabilization effect of the electron-withdrawing p-chloro- and pentalluorophcnyl groups attached to carbon atoms in sulfur ring, the electron-withdrawing p-lrilluoromethyl group on subsliluenls attached to sulfur decreases the stability of thiabenzenes. 相似文献
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A simple, fast and sensitive square-wave voltammetric (SWV) method for the determination of trace amounts of Captopril in pharmaceutical formulation and reconstituted serum is reported. A three-electrode system containing the static mercury drop electrode (SMDE) working electrode, Pt auxiliary electrode and Ag/AgCl reference electrode was used throughout. Sodium sulfite was used as both supporting electrolyte and oxygen removing agent. No nitrogen purging is needed for oxygen removal from sample solution. Calibration graph showed good linearity in the concentration range of 0.5-50.0 μg mL−1 of Captopril and regression coefficient of 0.9957 is obtained. R.S.D. for eight replicate measurements and LOD of the proposed method are 1.2% and 6.28 × 10−3 μg mL−1, respectively. The effect of various parameters (equilibration time, scan increment, pulse height, drop size, frequency and sodium sulfite concentration) on the determination were investigated. The procedure was successfully applied to the determination of Captopril in pharmaceutical formulation and reconstituted serum. 相似文献
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New derivatives of 5(4H)-quinazolinone containing 2-imidazolin-5-one rings have been prepared from 5(4H)-oxazolone derivatives. 相似文献
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Syntheses and photoisomerization of the new sulfone derivatives, 4,4‐di (p‐trifluoromethylphenyl)‐2,6‐diphenyl‐4H‐thiopyran‐1, 1‐dioxide and 4‐(p‐trifluoromethylphenyl)‐2,4,6‐triphenyl‐4H‐thiopyran‐1,1‐dioxide, have been investigated. The relative molar ratios of the photoproducts are compared with those of 2,4,4,6‐tetraphenyl‐4H‐thiopyran‐1,1‐dioxide as well as electron‐donating substituted 4‐methyl‐2,4,6‐triaryl‐4H‐thiopyran‐1,1‐dioxides as model compounds under identical experimental conditions using 1H NMR spectroscopy. The results observed are discussed on the basis of a triplet excited state di‐π‐methane rearrangement. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:557–561, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20455 相似文献
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Hooshang Pirelahi Assieh Atarodiekashani Seyyedmajid Seyyedmoossavi Hossein Daryanavardedargahani 《Monatshefte für Chemie / Chemical Monthly》2004,135(8):973-978
Summary. The photoisomerization of 4,4-dialkyl-2,6-diphenyl-4H-thiopyrans and 4-benzyl-2,4,6-triphenyl-4H-thiopyran was investigated and compared with those of the 2,4,4,6-tetraaryl- and 4-alkyl-2,4,6-triaryl-4H-thiopyran analogues reported earlier. Obviously, the alkyl groups at the 4-positions of the 4H-thiopyrans strongly diminish the efficiency of the di--methane rearrangement and, contrastingly, a four-electron suprafacial [1,3]-sigmatropic rearrangement is found to be highly efficient. 相似文献
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Arash Mouradzadegun Hooshang Pirelahi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):193-199
Abstract The effects of phenyl and methyl groups at 3,5-positions of tetrasubstituted 4H-thiopyrans 1a and 1b on photoisomerization are investigated from a kinetic point of view using 1H-NMR spectroscopy. On irradiation of 1a-1d in benzene-d6 solution the hexasubstituted 4H-thi-opyrans 1c and 1d, unlike those of the tetrasubstituted analogues 1a and 1b, give the isomeric 2H-thiopyrans 3c and 3d with no detectable signals for intermediates in 1H-NMR spectra. The photoisomerization of hexasubstituted 4H-thiopyrans 1c and 1d occur with relative rate constants lower than the corresponding tetrasubstituted model compounds 1a and 1b. Moreover, the kinetic comparison of 1a with 1b reveal that the presence of two phenyl groups at 4-position of tetrasubstituted 4H-thiopyran increases the relative rate constant of photoisomerization. 相似文献
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Novel sulfate ion-selective polymeric membrane electrode based on a derivative of pyrilium perchlorate 总被引:1,自引:0,他引:1
Ganjali MR Naji L Poursaberi T Taghizadeh M Pirelahi H Yousefi M Yeganeh-Faal A Shamsipur M 《Talanta》2002,58(2):359-366
A sulfate ion-selective PVC membrane sensor based on 4-(4-bromophenyl)-2,6-diphenylpyrilium perchlorate (BDPP) as a novel sensing material is successfully developed. The electrode shows a good selectivity for sulfate ion with respect to common organic and inorganic anions. The sensor exhibits a good linear response with slope of -28.9+/-0.5 mV per decade over the concentration range of 1.0x10(-6)-1.0x10(-2) M, and a detection limit of 8.0x10(-7) M of SO(4)(2-) ions. The electrode response is independent of pH in the range of 4.0-9.0. The proposed sensor was applied as an indicator electrode in potentiometric titration of sulfate and barium ions, and to the determination of zinc in zinc sulfate tablets. 相似文献