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31.
K. Lal 《Monatshefte für Chemie / Chemical Monthly》1983,114(1):33-36
Reactions of trimethylchlorosilane (Me 3SiCl) with some nitrogen donors viz. pyridine, 2-, 3- and 4-picolines, quinoline and isoquinoline in nitrobenzene have been studied conductometrically. The conductivities of the solutions during these reactions have been interpreted in terms of the formation of (Me 3Si.D)+, (Me 3SiCl2)? andMe 3SiCl.D (D=N-donor molecule) species. 相似文献
32.
An efficient [4+2] cyclization of N-methylanilines with maleimides to afford tetrahydroquinolines using N-hydroxyphthalimide as a metal-free and cheap organophotoredox catalyst is reported. The protocol involves C(sp3)H activation of N-methylanilines for the formation of α-amino radical without an oxidant at room temperature. The present method describes an easy preparation of tricyclic heterocycles in good to excellent yields under mild reaction conditions. 相似文献
33.
34.
Earlier work by Lindenbaum and Boyd has demonstrated the important role of hydrophobic interactions involving the water solvent in determining the osmotic coefficients and properties of aqueous solutions of the tetraalkylammonium halides. Osmotic coefficients of solutions of tetramethyl-, tetraethyl-, tetrapropyl-, and tetrabutylammonium bromides in the more highly structured solvent D2O have now been determined by the gravimetric isopiestic method, using reference solutions of NaCl in D2O. The data were fitted to the Rush-Johnson and Pitzer equations. Satisfactory agreement with the results for aqueous solutions at comparable concentrations indicates that the solution chemistry of these quaternary ammonium bromides is not highly dependent on the degree of structure of the pure solvents. Supplementary data for mixtures of Me4NBr with Et4NBr, Pr4NBr, or Bu4NBr in both H2O and D2O are consistent with this conclusion.On leave 1980–82 from Banaras Hindu University, India 相似文献
35.
Muhammad Saad Khan Cornelius Borecho Bavoh Khor Siak Foo Azmi Mohd Shariff Zamzila Kassim Nurzatil Aqmar Bt Othman Bhajan Lal Iqbal Ahmed Mohammad Azizur Rahman Sina Rezaei Gomari 《Molecules (Basel, Switzerland)》2021,26(2)
This study evaluates the kinetic hydrate inhibition (KHI) performance of four quaternary ammonium hydroxides (QAH) on mixed CH4 + CO2 hydrate systems. The studied QAHs are; tetraethylammonium hydroxide (TEAOH), tetrabutylammonium hydroxide (TBAOH), tetramethylammonium hydroxide (TMAOH), and tetrapropylammonium hydroxide (TPrAOH). The test was performed in a high-pressure hydrate reactor at temperatures of 274.0 K and 277.0 K, and a concentration of 1 wt.% using the isochoric cooling method. The kinetics results suggest that all the QAHs potentially delayed mixed CH4 + CO2 hydrates formation due to their steric hindrance abilities. The presence of QAHs reduced hydrate formation risk than the conventional hydrate inhibitor, PVP, at higher subcooling conditions. The findings indicate that increasing QAHs alkyl chain lengths increase their kinetic hydrate inhibition efficacies due to better surface adsorption abilities. QAHs with longer chain lengths have lesser amounts of solute particles to prevent hydrate formation. The outcomes of this study contribute significantly to current efforts to control gas hydrate formation in offshore petroleum pipelines. 相似文献
36.
Patel Urvi Girme Aboli Patel Kalpana Ghule Chetana Hingorani Lal Gandhi Tejal 《平面色谱法杂志一现代薄层色谱法》2021,34(3):217-228
JPC – Journal of Planar Chromatography – Modern TLC - The objective of the present work was to develop a simple, specific, and fast high-performance thin-layer chromatographic (HPTLC)... 相似文献
37.
The direct oxidation of chiral amide enolates to optically active mandelic acid using 2-sulfonyloxaziridine is described. The diastereoselectivity is counterion dependent. 相似文献
38.
Masami Kamigaito Tapan K. Lal Robert M. Waymouth 《Journal of polymer science. Part A, Polymer chemistry》2000,38(Z1):4649-4660
A series of Me4Cp–amido complexes {[η5:η1‐(Me4C5)SiMe2NR]TiCl2; R = t‐Bu, 1 ; C6H5, 2 ; C6F5, 3 ; SO2Ph, 4 ; or SO2Me, 5 } were prepared and investigated for olefin polymerization in the presence of methylaluminoxane (MAO). X‐ray crystallography of complexes 3 and 4 revealed very long Ti N bonds relative to the bonds of 1 . These complexes were employed for ethylene–styrene copolymerizations, styrene homopolymerizations, and propylene homopolymerizations in the presence of MAO. The productivities of the catalysts derived from 3 – 5 were much lower than the productivity of the catalyst derived from 1 for the propylene polymerizations and ethylene–styrene copolymerizations, whereas the styrene polymerization activities were much higher for the catalysts derived from 3 – 5 than for the catalyst derived from 1 . The polymerization behavior of the catalysts derived from the metallocenes 3 – 5 were more reminiscent of monocyclopentadienyl titanocene Cp′TiX3/MAO catalysts than of CpATiX2/MAO catalysts such as 1 containing alkylamido ligands. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4649–4660, 2000 相似文献
39.
Kanchan Kothari Ramji Lal M. R. A. Pillai 《Journal of Radioanalytical and Nuclear Chemistry》1995,196(2):331-338
A direct radioimmunoassay for the measurement of progesterone in human serum is described. Progesterone 11-hemisuccinate was conjugated to tyrosine methyl ester (TME) by the mix anhydride method and then iodinated using chloramine-T. The radiochemical purity of different batches of125I-progesterone was greater than 95% and showed 70–75% binding with excess antibody. Progesterone 11-hemisuccinate was coupled with BSA and injected to rabits. Antisera collected after three booster injections and having aK value of 1·1091/M was selected for the assay. Significant reduction in binding with antibody was seen when hormone free serum was used in the assay system. Various blocking agents were tried to reduce the serum effects and none of them were found satisfactory. From a series of optimization experiments, an assay was developed without the use of blocking agents. This assay used a much higher concentration of antibody along with lower amount of serum sample (50 l). The optimized assay has a sensitivity of 0.5 nj/ml and a working range of 0.5 to 100 ng/ml. Serum samples were analyzed analysis showed good correlation between the results obtained from the present system and the DPC kit. (Y=0.93X+0.5,r=0.93, forn=25). 相似文献
40.
An approach has been developed for the quantitative determination of concentrations of centchroman ( I), a nonsteroidal once‐a‐week oral contraceptive, and its major metabolite (7‐desmethyl centchroman, II) using dried blood spots (DBS) on paper, rather than conventional plasma samples. The assay employed simple solvent extraction of the DBS sample circle (6 mm) requiring small blood volumes (30 μL) followed by reversed‐phase HPLC separation, combined with multiple reaction monitoring mass spectrometric detection. The calibration plot in matrix using d ‐trans‐hydroxy chroman as internal standard (IS) was linear (r2 = 0.998) over ranges of 1.5–240 and 4.5–720 ng/mL for I and II, respectively. The recoveries of both I and II were always >60% with quantification limits (signal‐to‐noise ratio = 10) of 1.5 and 4.5 ng/mL for I and II, respectively. The intra‐day and inter‐day precision (%RSD) and accuracy (%bias) variations in blood spots for both I and II were better than 13%. Moreover, both I and II were stable in DBS for at least 3 months when stored at room temperature. The developed method was successfully applied to the pharmacokinetic interaction study after oral administration of centchroman with and without co‐administration of carbamazepine in female Sprague–Dawley rats using serial sampling and results were comparable with the plasma concentrations reported earlier. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献