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61.
Gary M. Coppola 《Journal of heterocyclic chemistry》1986,23(1):223-224
Isatoic anhydrides 1 are easily reduced with sodium borohydride to o-(substituted-amino)benzyl alcohols 3 in good yield. Sequential reduction of N-(2-nitrobenzyl)isatoic anhydride ( 5 ) with sodium borohydride followed by catalytic hydrogenation of the nitro group affords the naturally occurring 2-(2′-aminobenzylamino)-benzyl alcohol ( 4 ) in 72% yield. 相似文献
62.
Gary W. Schnuelle S. Swaminathan David L. Beveridge 《Theoretical chemistry accounts》1978,48(1):17-27
A theoretical study of ion hydration using the statistical thermodynamic supermolecule-continuum method is described. The cell and shell methods are used for configurational averaging. Enthalpies, free energies and entropies are calculated for Li+, Na+, K+, F– and Cl– each four coordinated with water. The results are in reasonable accord with experiment. A comparison of the site method, cell method and shell method results is presented. The supermolecule-continuum approach to solvent effects seems to be capable of accommodating essential features for the calculation of solvation energy and solvent effects on structure and properties. 相似文献
63.
Liu L John VT McPherson G Maskos K Bose A 《Langmuir : the ACS journal of surfaces and colloids》2005,21(9):3795-3801
A viscous reverse hexagonal surfactant mesophase containing bis(2-ethylhexyl) sodium sulfosuccinate (AOT) and alpha-phosphatidylcholine (lecithin), with comparable volume fractions of isooctane and water, was characterized by Fourier transform (31)P and (1)H NMR spectroscopy. Shear alignment was reflected through both (31)P NMR and (1)H NMR spectra. A complicated (31)P spectrum was observed as a result of superposition of chemical shifts according to the distribution of crystalline domains prior to shear. The initially disordered samples with polydomain structures become macroscopically aligned after Couette shear. (31)P NMR chemical shift anisotropy characteristics are used to elucidate orientation of the hexagonal phase. Interestingly, (1)H NMR spectra exhibit spectral changes upon shear alignment closely corresponding with that of (31)P NMR spectra. These observations complement the findings of mesophase alignment obtained using SANS and imply that (31)P and (1)H NMR spectroscopy can be used as probes to define microstructure and monitor orientation changes in this binary surfactant system. This is especially beneficial if these mesophases are used as templates for materials synthesis. 相似文献
64.
Brett Ammundsen Gary R. Burns Ali Amran Stig E. Friberg 《Journal of Sol-Gel Science and Technology》1995,4(1):23-29
The effects of thermal treatment on composite materials prepared by the gelation of sols comprising large concentrations of metal oxide precursor salts have been investigated, in order to determine the compositional and thermal requirements for forming spinel magnesium manganates in such systems. The preparative technique has been found to give rise to derived gel materials in which the metal oxide phase, in the form of regular spherical particles, is dispersed throughout a continuous silica matrix. Silica-supported mixed magnesium and manganese spinel oxide phases were obtained for systems comprising at least 30 wt% metal nitrate after heating to temperatures between 700 and 850°C, but not without concomitant formation of Mn2O3 and modification of the silica network by magnesium. 相似文献
65.
Gary W Caldwell John A Masucci Mary Evangelisto Robert White 《Journal of chromatography. A》1998,800(2):1071-169
Chromatographic retention factors (k′) of a series of eight β-adrenoceptor antagonist compounds (β-adrenolytic drugs) were determined employing an immobilized artificial membrane column (IAM.PC.DD). The influence of mobile phase pH, ionic strength, and organic modifier composition was studied in order to examine column performance. After the IAM.PC.DD columns were exposed to approximately 7000 column volumes of a 0.01 M PBS mobile phase, five out of six columns tested showed significant peak broadening and decreased k′ values indicative of premature column failure. The data suggested that the immobilized phospholipids stationary phase was removed by the 0.01 M PBS mobile phase. The β-adrenolytic drug's log k′IAM values obtained with an IAM.PC.DD column were compared to an esterIAM.PC.MG column for predicting drug membrane interactions. For the linear regression analysis between log k′IAM and the logarithm of the n-octanol–water partition coefficients (rIAM.PC.DD=0.8710 vs. rIAM.PC.MG=0.9538), the C18 HPLC retention factors (rIAM.PC.DD=0.8408 vs. rIAM.PC.MG=0.9380), the liposome partition coefficients (rIAM.PC.DD=0.8887 vs. rIAM.PC.MG=0.9187), and various pharmacokinetic parameters, significantly better correlations were obtained with the esterIAM.PC.MG column than the IAM.PC.DD column. 相似文献
66.
Kritsana Jitmanee Jaroon Jakmunee Somchai Lapanantnoppakhun Sunanta Wangkarn Norio Teshima Tadao Sakai Gary D. Christian Kate Grudpan 《Microchemical Journal》2007,86(2):195-203
Derivative techniques for analytical signal processing are useful for solving some noise and signal resolution problems in various fields of study such as titrimetry, spectrophotometry, chromatography and electrochemistry. The broad use of these techniques, however, is often limited by costly inflexible built-in software packages in commercial analytical instruments. We propose here the application of commercial simple software packages such as Microsoft® Excel and Microcal Origin for signal smoothing and fitting, and for obtaining derivative analytical signals in batch and flow-based analyses, including potentiometric titration, spectrophotometry, chromatography, voltammetry and sequential injection analysis (SIA). The worldwide (especially Excel) software packages are easy-to-use for less experienced users and have also capabilities for advanced users, and therefore employing such packages can result in expansion of useful derivative techniques. We demonstrate application of the available package-aided derivative capabilities for enhancing some chemical analyses, including potentiometric acid–base titration, Bradford assay of protein, chromatographic separation of ajmaline and reserpine and anodic stripping voltammetry of copper. The derivative signals from smoothed and fitted curves offer better accuracy and precision, even for non-resolving peaks and tailing peaks. In some cases, the optimization of experimental conditions is not further required, which can lead to fast method development. 相似文献
67.
Jiann-Kuan Luo Andrew S. Zektzer Raymond N. Castle Ronald C. Crouch John P. Shockcor Gary E. Martin 《Journal of heterocyclic chemistry》1993,30(2):453-460
Two novel heterocyclic ring systems, namely, [1]benzothieno[2,3-c]naphtho[1,2-f]quinoline and [1]benzothieno[2,3-c]naphtho[2,1-g]quinoline have been synthesized and characterized by inverse detected two-dimensional nmr methods. Unequivocal total assignments of the proton and carbon nmr spectra were made through the concerted utilization of HMQC (Heteronuclear Multiple Quantum Correlation) and a combination of HMBC (Heteronuclear Multiple Bond Correlation) and HMQC-TOCSY (HMQC with proton TOtal Correlation Spectroscopy). 相似文献
68.
A new photoelectron spectroscopic method is described directed towards the measurement of the photoelectron spectra of trapped ions. An electrostatic retarding field electron energy analyser incorporating a channel plate is included with an ion trap in a strong magnetic field. The form of photoelectron spectrum is shown to be strongly influenced by a elastic scattering effects which can be enhanced by using an electron trapping potential well. The resultant spectra then have a particularly simple and useful form. 相似文献
69.
Using a modified photoelectron spectrometer the radiative lifetimes of some electronically excited diatomic and triatomic molecular ions have been determined. The method is based on measuring the time delay between the ejection of a photoelectron from a molecule and the emission of a photon from the resulting ion. 相似文献
70.
M. J. Musmar M. Robert Willcott Gary E. Martin Robert T. Gampe Masatomo Iwao Milton L. Lee Ralph E. Hurd Leroy F. Johnson Raymond N. Castle 《Journal of heterocyclic chemistry》1983,20(6):1661-1669
Development of successively higher field nmr spectrometers has facilitated the study of increasingly more complex molecules, although smaller molecules such as phenanthro[3,4-b]thiophene still offer very substantial assignment problems because of the highly congested nature of their 1H- and 13C-nmr spectra. Assignments of such spectra, if they are to be unequivocal, frequently require the utilization of two-dimensional nmr spectroscopic techniques. Total assignments of the 1H- and 13C-nmr spectra of phenanthro[3,4-b]thiophene are reported. Assignments were based on a conventional high resolution 500 MHz 1H-nmr spectrum, autocorrelated two-dimensional 1H-nmr spectra (COSY), two-dimensional 1H-13C chemical shift correlation spectra and a modified version of autocorrelated 13C-13C double quantum coherence two-dimensional nmr spectroscopy. From NOE measurements, a separation of 1.99 Å between H1 and H11 was computed, suggesting that phenanthro[3,4-b]thiophene has a pronounced helical conformation in solution. 相似文献