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22.
Thierry Boulanger Daniel P. Vercauteren Guy Evrard François Durant 《Journal of chemical crystallography》1987,17(5):561-573
The crystal structure of 2-(carboxy-3-propyl)-3-amino-6-cyclohexylpyridazinium bromide has been determined by single-crystal X-ray diffraction techniques and refined by full-matrix least squares. The compound crystallized in the tri-clinic space groupP ¯1 witha=10.275(1),b=11.215(1),c=7.082(1) Å,=91.84(1),=102.21(1), =106.77(1)°, andZ=2. FinalR-factor is 0.045. The main structural results are very similar to the ones observed for the 6-phenyl analog. These two compounds are GABA-A antagonists.Ab initio molecular orbital calculations, with STO-3G and 4-31G basis sets, suggest that the exocyclic nitrogen accurately mimics the nitrogen atom of GABA. 相似文献
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24.
Cox DL 《Physical review letters》1987,59(11):1240-1243
25.
A steady-state system involving photolysis of HONO as a source of OH was used to investigate the reaction of OH with CS2 at 1 atm and 295 K. In the presence of O2 ( > 40 Torr) a rapid reaction of OH with CS2 occurs giving OCS. At lower O2 concentrations, OCS formation ceases. In air the overall rate constant for OH + CS2 → OCS was (1.7 ± 0.9) × 10?12 cm3 molecule?1 s?1. 相似文献
26.
Pham-Tran NN Bouchoux G Delaere D Nguyen MT 《The journal of physical chemistry. A》2005,109(12):2957-2963
We have investigated the basicity of phosphinine (C5H5P, phosphabenzene) in reevaluating its proton affinity (PA) and gas-phase basicity (GB) and the pK(a) value of its protonated form. As a necessary step, we have first determined its gas-phase proton affinity. Using both mass spectrometric and quantum chemical methods, we have obtained the values PA(C5H5P) = 195.8 +/- 1.0 kcal mol(-1) and GB(298)(C5H5P) = 188.1 +/- 1.0 kcal mol(-1), in good agreement with previous results. We then derived a value of pK(a)(C5H6P+) = -16.1 +/- 1.0 in aqueous solution using three different approaches: the latter markedly differs from the currently available value of -10. The reason for such a discrepancy in the pK(a) of protonated phosphinine in solution is discussed. In the theoretical determination of PAs, evaluation of the basis set superposition error (BSSE) showed that this effect is quite small, being 0.1-0.2 kcal mol(-1) for phosphinine, when a density functional theory (DFT) method in conjunction with a large basis set were used. 相似文献
27.
The electrolytic sensor described is based on the oxidation of nitrite at a platinum electrode modified with chemisorbed iodine and coated with a thin layer of quaternized poly(4-vinylpyridine), qPVP. The sealed sensor uses an anion-exchange membrane to separate Donnan transport of nitrite across the membrane and controlled potential electrolysis at the Pt/qPVP indicator electrode. The sensor has a linear response to nitrate concentration in aqueous samples over the range 4 × 10?6?2 × 10?3 M nitrite. The detection limit is 2 × 10?6 M nitrite. The sensor is free of interference by nitrate, dissolved oxygen, cations, and many neutral species. Anions that are electroactive at 0.7 V vs. Ag/ AgCl would interfere, but they are uncommon in most samples. Initial tests with lake water samples suggest that this sensor is unaffected by this matrix. The system was also evaluated for monitoring nitrite levels in spiked meat extracts. 相似文献
28.
Neil G. Connelly John G. Crossley A. Guy Orpen Henrietta Salter 《Journal of organometallic chemistry》1994,480(1-2):c12-c13
The reaction of [NBu4n]2Cu(mnt)2] with [Pt(CNMe)4][PF6]2 gives [Pt(mnt)(CNMe)2]·(NC)2C2S2CNMe, an X-ray study of which reveals co-stacking of neutral planar metal and organic molecules. 相似文献
29.
Cooper SM Laosripaiboon W Rahman AS Hothersall J El-Sayed AK Winfield C Crosby J Cox RJ Simpson TJ Thomas CM 《Chemistry & biology》2005,12(7):825-833
Mupirocin, a polyketide-derived antibiotic from Pseudomonas fluorescens NCIMB10586, is a mixture of pseudomonic acids (PA) that target isoleucyl-tRNA synthase. The mup gene cluster encodes both type I polyketide synthases and monofunctional enzymes that should play a role during the conversion of the product of the polyketide synthase into the active antibiotic (tailoring). By in-frame deletion analysis of selected tailoring open-reading frames we show that mupQ, mupS, mupT, and mupW are essential for mupirocin production, whereas mupO, mupU, mupV, and macpE are essential for production of PA-A but not PA-B. Therefore, PA-B is not simply produced by hydroxylation of PA-A but is either a precursor of PA-A or a shunt product. In the mupW mutant, a new metabolite lacking the tetrahydropyran ring is produced, implicating mupW in oxidation of the 16-methyl group. 相似文献
30.
A large‐scale synthetic route to a variety of phosphaformamidines and phosphaformamidinates, a type of derivative that was not accessible by the methods previously known for preparing phosphaamidines and phosphaamidinates, is reported. Thermally stable ethyl N‐arylformimidates 1 (ArN?CH(OEt), Ar=2,4,6‐(Me)3Ph or 2,6‐(iPr)2Ph) readily reacted with lithium dialkyl‐ and diarylphosphanides to afford the corresponding N‐aryl phosphaformamidines in 80 and 60 % yield, respectively, whereas with lithium (aryl)(silyl)phosphanide, the N‐aryl‐N‐silylphosphaformamidine (60 % yield) was obtained. Addition of primary lithium arylphosphanides to 1 followed by addition of a stoichiometric amount of nBuLi gave rise to the respective phosphaformamidinates (70–88 % yield). Methanolysis of the products afforded the N‐aryl‐N‐hydrogenophosphaformamidines (90–95 % yield). The solid‐state structure of one of the phosphaformamidinates is also presented. 相似文献