- Sunday, January 1, 2006
- Published at:Not Found
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An-Najah University Journal for Research - Natural Sciences (A) ISSN: 1727-2114
Volume 20 , 2006, Pages: 207-212
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- Tuesday, April 1, 2003
- Published at:Not Found
- Reactions of morpholine, piperidine, and piperazine with Os(VIII)-catalyzed hexacyanoferrate(III) in alkaline media to produce the corresponding lactam have been studied at constant temperature and ionic strength. The reactions followed first-order kinetics with respect to [amine] and [Os(VIII)] but were independent of [Fe(CN)6 3-] and [OH-]. The effects of introduced electrolytes, potassium hexacyanoferrate(II), relative permitivity, and temperature have also been studied. A mechanism accounting for these results has been proposed.
Chemistry of Heterocyclic Compounds, Volume 39, Number 4 / April, 2003
http://www.springerlink.com/content/j06688m34677p8w0/
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- Tuesday, January 1, 2002
- Published at:Not Found
- Dethiation of α-(3–benzoylphenyl)-α-methyl and α-phenylmercaptopropi-onic acid (I & II) with Raney nickel is described
An-Najah University Journal for Research - Natural Sciences (A) ISSN: 1727-2114
Volume 16 , Issue 1 , 2002, Pages: 057-061
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- Monday, January 1, 2001
- Published at:Not Found
- Oxidation of some alicyclic amines (morpholine, piperazine and piperidine) by potassium hexacyanoferrate(???) in basic medium has been investigated at 35°C. Stoichiometric results showed that four moles of hexacyanoferrate(III) were consumed per mole of piperidine or morpholine whereas piperazine consumed eight moles of the oxidant to produce the corresponding lactams. Kinetic studies indicated that piperidine and morpholine also followed different kinetics from that of piperazine, being first order in the amine concentration and independent of the concentrations of hexacyanoferrate(???) and hydroxide ion, while in the case of piperazine, the reaction was first order in both oxidant and substrate concentrations and zero order with respect to the concentration of hydroxide ion. The changes in reaction rate due to changing ionic strength of the medium as well as other factors has also been investigated. The activation parameters of the oxidation process have been evaluated and a mechanism consistent with th
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- Monday, January 1, 2001
- Published at:Not Found
- Two spectrophotometric methods are described for the determination of tiopronin in pharmaceuticals. They are based on the oxidation-reduction reaction between tiopronin and iron (III), then forming a complex between iron (II) and ferrozine or di-2-pyridyl ketone-2-thiophenoylhydrazone. The produced colored iron (II)-ferrozine complex [system I] absorbs at 562 nm, while the iron (II)-di-2-pyridyl ketone-2-thiophenoylhydrazone complex [system II] absorbs at 656 nm. The effect of different factors such as: pH, reagent concentration, time of reaction, temperature and the tolerance amount of the common excipients have been studied. Applying the optimum working conditions, tiopronin can be determined over the range 0.2-8.6 and 0.5-17.0 ppm and with molar absorptivities of 2.0x104 and 1.0x104 l mol-1cm-1 for systems I and II, respectively. Both methods offer high selectivity, sensitivity and accuracy with a relative standard deviation (RSD) of less than 1.1% for five measurements. The proposed methods were applied s
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