NMR Studies of Drugs: Antipyrine and Analogs. I. Use of Achiral and Chiral Lanthanide Shift Reagents to Examine Hindered Rotation.

The 200 MHz ¹H NMR spectra of the analgesic, antipyrine, 1, have been studied in CDC1₃ solution at ambient temperatures with the achiral lanthanide shift reagent (LSR) tris (6, 6, 7, 7, 8, 8, 8-heptafluoro-2, 2-dimethyl-3, 5-octanedionato) europium (III), Eu(FOD)₃, 2, and with the chiral LSR, tris[3-(heptafluoropropylhydroxymethylene)-(+)-camphorato]europium(III), Eu(HFC)₃, 3., Lanthanide-induced shift (LIS) magnitudes and broadening of selected signals are consistent with predominant LSR binding at the carbonyl oxygen with either 2 or 3. Of the different possible conformational regimes for the N-phenyl group of 1, our results appear to rule out a slow exchange limit (SEL) system with the N-phenyl coplanar with the heterocyclic ring. Perpendicular rings in an SEL regime can not be ruled out. A rapidly-rotating N-phenyl (fast exchange limit, FEL system) would also be consistent with observed results. Accurate chemical shifts for the aryl protons (overlapped in the 200 MHz spectrum of unshifted 1) are determined from spectra with added LSR by extrapolation to zero molar ratios of [LSR]:[1]. Relative slopes in the plots of chemical shift versus [LSR]:[1] molar ratios are calculated for each proton signal of 1.     

NMR Studies Of Drugs. Chiral Solvating Agents for Direct Determination of Enantiomeric Excess of the Cardiac Antiarrhythmic,Mexiletine

The 400 MHz ¹H NMR spectra of the cardiac antiarrhythmic, mexiletine, 1, have been studied with different chiral solvating agents (CSA) to obtain a very promising method for direct determination of enantiomeric excess (e.e.) with limited amounts of 1. The methods included the use of β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD), α-methoxy-α-(trifluoromethyl)phenylacetic acid (MTPA), and 2,2,2-trifluoro-1-(9-anthryl)ethanol (TFAE). Use of TFAE in CDCl₃ with the free base of 1 appeared to give the best results, with enantiomeric shift differences observed for the signals of the sidechain methyl, CH ₃CH, and the aryl methyls.     

Kinematical and Dynamical Inelastic Light Scattering in Conducting Crystals

Fundamentals of the kinematical quantum theory of inelastic light scattering from electronic excitations in conducting crystals are reviewed. Keeping both the →Δ and →p·→A terms in the photon-electron interaction the general expression for the differential scattering cross-section is obtained. Emphasizing opacity effects and anisotropies arising from the Doppler shift the scattering kinematics is analyzed. The scattering from free-carrier density fluctuations is considered briefly. The basic concepts of a recently established phenomenological theory of dynamical light diffraction in opaque crystals are discussed, and some aspects of a predicted phonon induced anomalous transmission of light below the plasma edge in semiconductors are studied.     

NMR Studies in the Heterocyclic Series. XXIII. - 13C Spectra of Indazole and 3-Azido-Indazole in Acidified Dimethylsulfoxid Solutions

We reported previously the ¹³C NMR spectra of indazole 1 ² and 3-azido-indazole 2 ³.     

Infrared Study of the Interaction of Tetramethylthiourea and Dimethylthioformamide with Phenol Derivatives

Abstract

The hydrogen bonded complexes between hydroxylic bonds and oxygen or nitrogen bases have been extensively studied by infrared spectrometry. However, meager experimental results are available for sulfur participation in hydrogen bond formation. There seems little doubt that in thioamides - hydroxylic complexes, the donor site for hydrogen bonding is sulfur, particularly in view of the blue shift of the n → π? transition of the thiocarbonyl group in proton donor solvents ¹. This paper reports on a study of the equilibrium constants (K) and on the frequency shifts of the 1 v _OH stretching vibration of hydrogen bonded complexes between tetramethylthiourea (TMTU) or dimethyltnioformamide (DMTF) and some phenol derivatives.     

The Vibrational Spectra and Normal Coordinate Analysis of Semiconducting Y2BaCuO5

Both infrared (FTIR) and Raman spectra have been measured for the green semiconducting Y₂BaCuO₅ (2:1:1) in the Y-Ba-Cu-O system. Factor group analysis and normal-coordinate-analysis calculations have been conducted for this phase in order to determine the symmetries, the wavenumber locations and the eigenvector nature of its first-order modes of vibration along with the appropriate set of modified GVF force constants. The predicted vibrational spectral results are in good agreement with the experimentally observed FTIR and Raman spectral data. The generated force constants are interpreted along with those for related phases on the basis of structure.     

NMR Studies of Drugs. 5-Methyl-5-phenylhydantoin. Applications of Lanthanide Shift Reagents in Polar Solvents to a Non-Chelating Substrate

The 200.1 MHz ¹H NMR spectra of 5-methyl-5-phenylhydantoin, 1, have been studied in CD₃CN solution at ambient temperatures with the achiral shift reagent, tris (6, 6, 7, 7, 8, 8, 8-heptafluoro-2,2-dimethyl-3,5-octanedionato) europium (III), 2, and the chiral reagent, tris[3-(heptafluoropropylhydroxymethylene)-(+)-camphorato] europium (III), 3. Although 1 cannot chelate the LSRs, use of sufficiently high LSR:1 molar ratios served to compensate for competitive binding of LSR by the polar solvent, and permitted substantial lanthanide-induced shifts to be observed with 2 or 3. With 3, significant enantiomeric shift differences were produced for the ortho aryl protons and for the CH₃ signals. The ortho proton signal appears to offer excellent potential for direct determination of enantiomeric excess of 1. These results demonstrate the utility of LSRs 2 or 3 even in a polar solvent with a nonchelating substrate.     

A Modified Version of the Grimm's Glow Discharge Lamp for Use as a Demountable Hollow Cathode Emission Source. V. Determination of Minor Constitutents and Trace Elements in Steel

The applicability of the modified hollow cathode emission source to the determination of some elements usually contained in steel was tested in the case of chromium (0.144 – 3.07%), copper (0.090 – 0.49%), manganese (0.016 – 1.42%), molybdenum (0.007 – 1.41%), nickel (0.048 – 5.15%, silicon (0.013 – 0.81%), and vanadium (0.034 – 0.64%). The linearity of the calibration curves was found to be highly satisfactory, the Bravais - Pearson correlation coefficient ranging from 0.97 to 0.99. Moreover, results showed that background intensity is negligible and that blackening values can be plotted without resorting to internal standards or other preliminary corrections.     

ITER校正场超导馈线系统地震分析

通过ANSYS建立校正场磁体馈线动力学分析有限元模型,利用反应谱法对馈线进行地震分析,获取馈线在地震载荷下的动力响应情况。分析结果表明,现有馈线结构设计可满足馈线地震要求。同时研究了支撑间隙对地震分析的影响,结果表明,馈线地震分析需要充分考虑支承间隙的影响。     

产业关联分析动态网络模型

投入产出关联效应分析模型应用完全经济关联关系的概念,较为全面的反映了产业部门间的关联关系.然而,传统的投入产出关联效应分析对产业部门间的关联关系做了简化处理,并没有考虑经济活动的传导时滞因素所产生的动态影响,这种处理方式使模型的应用受到较多限制.利用有向加权网络工具,考虑经济活动的传导时滞,构建了产业关联分析动态网络模型.该模型与传统投入产出模型相比具有以下三个特点:一是考虑了产业部门间及部门内部传导时滞的作用,对部门间关联效应及传导过程作了动态描述,使其关联关系更加符合实际;二是可计算任意时点上一个部门产量的变化对系统中各部门关联效应的大小;三是该模型经济含义直观,易于理解,且易于利用计算机仿真模拟.