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The various thermodynamic parameters for the periodate oxidation of six anilines, viz. aniline, p-chloroaniline, p-ethoxyaniline, o- and p-methoxyanilines and p-methylaniline have been reported and discussed. The validity of the isokinetic relationship and various linear free energy relationships (LFERs) have been tested and discussed. An attempt has been made to correlate these findings with the mechanism operative in these reactions. 相似文献
44.
Hwu JR Jain ML Tsai FY Tsay SC Balakumar A Hakimelahi GH 《The Journal of organic chemistry》2000,65(17):5077-5088
Silica gel-supported ceric ammonium nitrate (CAN-SiO2) was found effective for rapid and selective cleavage of trityl (Tr), monomethoxytrityl (MMTr), and dimethoxytrityl (DMTr) groups from protected nucleosides and nucleotides under mild conditions. Efficiency of deprotections depended upon the stability of the resultant carbocationic species: DMTr+ > MMTr+ > Tr+. Use of a catalytic amount of this solid-supported reagent can also efficiently and selectively remove the tert-butyldimethylsilyl or the triisopropylsilyl group from a primary hydroxyl functionality in di- or trisilyl ethers of ribonucleosides. A comparative study of deprotection reactions by utilization of CAN alone or CAN-SiO2 indicates a remarkable increase in the rate of the reactions involving a solid support. The mechanism of electron-transfer processes is proposed for the use of CAN-SiO2 in the removal of these protective groups from organic molecules. 相似文献
45.
Krishna C. Joshi Renuka Jain Anshu Dandia Vandana Sharma 《Journal of heterocyclic chemistry》1986,23(1):97-99
A novel system 2-oxo-1′,2′,4′,5′-tetrahydrospiro[3H-indole-3,3′-1,2,4,5-tetrazine]-6′-thione has been synthesized by the treatment of fluorinated isatins with thiocarbohydrazide in aqueous ethanolic medium. Under exactly similar conditions, N-acetylisatin gave exclusively thiocarbohydrazone. The spiro product, on treatment with acetic acid, gave fluorinated isoindigo. Characterization of these products have been done by elemental analyses, ir, pmr and mass spectral studies. 相似文献
46.
A. K. Maheshwari Dr. D. S. Jain J. N. Gaur 《Monatshefte für Chemie / Chemical Monthly》1977,108(2):279-283
The reduction of Cd(II) in propylenediamine was found to be reversible and diffusion controlled. The complexes of Cd(II) with propylenediamine in 25%, 50%, and 75% dimethylformamide have been studied polarographically using theDeFord andHume's treatment as extended byIrving. Increase in the stability constants was observed with increase in dimethylformamide percentage. The percentage composition of the various complexed and uncomplexed species in 25% and 50% dimethylformamide are presented. 相似文献
47.
Duli C. Jain Denyse De Gale Anne-Marie Sapse 《Journal of computational chemistry》1989,10(8):1031-1037
A continuum and a discrete-continuum models are used to determine the solvation energies of FCH2COO?, FCH2COOH, and F2CHCOO?. For the anions, the continuum model provides results closer to the experiment, while for the acid, the addition of one water molecule improves the continuum-only energy. 相似文献
48.
The first enantioselective synthesis of (8S,13S,14R)-7-oxa-estra-4,9-diene-3,17-dione with the trans-C/D ring junction is described. Key features of the synthesis include Ag2O-mediated C-O bond formation, thermodynamically controlled axial-equatorial inversion, one-pot of halogen exchange and Co/Cr-mediated C-C bond formation, and intramolecular aldol condensations. 相似文献
49.
The reaction of N-arylcyanamides with thiophene o-aminonitriles under the influence of dry hydrogen chloride gas yields a mixture of two products. The major product has been identified as 2-amino-3-aryl-4-iminothieno[2,3-d]pyrimidine and the minor as 2-amino-3-arylthieno[2,3-H]pyrimidin-4(3H)-one. 相似文献
50.
The thermal ignition behaviour of various mixtures of organic fuels, magnesium and ammonium nitrate (AN) has been examined by differential thermal analysis technique. It has been observed that the thermal decomposition/ignition of organic fuel-AN mixtures is modified significantly in the presence of magnesium metal. The decomposition characteristics of the binary mixtures of AN with various metals indicate the specific action of magnesium and zinc in lowering the decomposition temperature. A possible explanation for the low temperature decomposition is given in terms of the solid state reaction causing the fusion of AN which further reacts with the metal resulting in a highly exothermic reaction.
Zusammenfassung Mittels DTA wurde das thermische Initiierungsverhalten verschiedener Gemische aus organischen Brennstoffen, Magnesium und Ammoniumnitrat (AN) untersucht. Es wurde festgestellt, daß die thermische Zersetzung/Initiierung von Gemischen aus organischen Brennstoffen und AN durch die Gegenwart von metallischem Magnesium bedeutsam beeinflußt wird. Die Zersetzungscharakteristiken binären Gemische aus AN und verschiedener Metalle zeigen eine spezielle Wirkung von Magnesium und Zink bei der Herabsetzung der Zersetzungstemperatur. Eine mögliche Erklärung für die Zersetzung bei niedrigerer Temperatur kann in Bezug auf die Festkörperreaktion gesehen werden, die das Schmelzen von AN verursacht, welches dann mit dem Metall stark exotherm reagiert.
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