- Kinetics of interaction of histidine and histidine methyl ester with ninhydrin in micellar media
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Kinetics of the interaction of histidine and histidine methyl ester with ninhydrin under varying concentrations of reactants, anionic (sodium dodecyl sulphate, SDS), cationic (cetyltrimethylammonium bromide, CTAB) and non-ionic (Triton X-100, TX-100) micelles have been carried out. Rate of the reaction was found to be independent of the initial concentration of histidine (and histidine methyl ester) but was dependent on [Ninhydrin]. The SDS micelles had no effect on the rate of the reaction. In the presence of the CTAB micelles a small enhancement in the rate was observed. The rate - [CTAB] profile showed that the increase in [CTAB] increased the rate up to a maximum value and a further increase had a decreasing effect on the rate. The rate was enhanced by TX-100 also but, unlike CTAB micelles, TX-100 possessed a curve without peak for the rate - [TX-100] profile. The following rate equation was obeyed by the reaction in CTAB and TX-100 micelles: 1kΨ = kw[N]T + (km KS - kw) [Dn] MNS/1 + KS [Dn] Values of kw, km, and KS were evaluated and are reported herein.
- Din, Kabir-Ud,Rafiquee,Akram,Khan, Zaheer
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- Effect of dicationic gemini surfactants 16-s-16 (s = 4, 5, 6) on the ninhydrin-dipeptide (glycyl-tyrosine) reaction
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The effect of dicationic gemini surfactants H33C 16(CH3)2N+-(CH2) s-N+(CH3)2 C16H 33, 2Br- (s= 4, 5, 6) on the reaction of a dipeptide glycyl-tyrosine (Gly-Tyr) with ninhydrin has been studied spectrophotometrically at 70°C and pH 5.0. The reaction follows first- and fractional-order kinetics, respectively, in [Gly-Tyr] and [ninhydrin]. The gemini surfactant micellar media are comparatively more effective than their single chain-single head counterpart cetyltrimethylammonium bromide (CTAB) micelles. Whereas typical rate constant (kψ) increase and leveling-off regions, just like CTAB, are observed with geminis, the latter produces a third region of increasing kψ at higher concentrations. This subsequent increase is ascribed to the change in the micellar morphology of the geminis. The pseudophase model of micelles was used to quantitatively analyze the k ψ - [gemini] data, wherein the micellar-binding constants K S for [Gly-Tyr] and KN for ninhydrin were evaluated.
- Akram, Mohd.,Kumar, Dileep,Kabir-Ud-Din
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- Effect of organic solvents (methylcellosolve, dimethylsulfoxide, acetonitrile and 1-propanol) on the tryptophan-ninhydrin reaction - A kinetic approach
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Kinetics of the tryptophan-ninhydrin reaction at a constant [Triton X-100] (=50.0 × 10-3 mol dm-3) and pH (=5.0), maintained by CH3COONa-CH3COOH, in presence of different organic solvents, i.e. methylcellosolve, dimethylsulfoxide, acetonitrile and 1-propanol, has been studied spectrophotometrically at 40°C. In each case, the pseudo-first-order rate constant increases with increase in the proportion of organic solvent. The catalytic role of solvents has been discussed in terms of increasing the solubility of Ruhemann's purple (the product) in the solvents and blocking the side reaction. Other reasons for the catalytic role of solvents have also been discussed.
- Kabir-Ud-Din,Fatma, Waseefa,Khan, Zaheer
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p. 811 - 813
(2007/10/03)
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- Chemistry of Free Cyclic Vicinal Tricarbonyl Compounds ('1,2,3-Triones'). Part 3. Polar and Redox Reactions of 1,2,3-Triones with Enamines of Different Types - News on Oxonol Dyes, Radicals, and Biradicals
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The central C=O groups of cyclic 1,2,3-triones possess outstanding electrophilic (electron-pair-accepting) as well as oxidizing (one-electron-accepting) properties. Thus, 1,2,3-triones are chemically related to 1,2- and 1,4-benzoquinones. Whereas polar reactions with carbanion-like (electron rich) species give rise to nucleophilic addition reactions to C=O groups under exclusive C,C-bond formation, SET (single-electron transfer) or redox reactions effect a partial 'carbonyl Umpolung' via ketyl intermediates (C,C- and/or C,O-bond formation). Here, we report on numerous reactions between electron-rich, more- or less-polar enamines with 5,5-dimethylcyclohexane-1,2,3-trione (9a) and 1H-indene-1,2,3-trione (9b). Various new derivatives of basic oxonol dyes were formed, including the first oxonol dye incorporating a 1,3-dioxocyclohexyl moiety. A novel stable radical, 50/50′, was obtained from 9b and lla via addition, hydrolysis, and treatment with conc. H2SO4. Radical 50/50′ represents a vinylogous 'monodehydroreductone' and is, thus, related to monodehydroascorbic acid (143), to Russell's radical cation (144), to indigo (141/141′), and to quinhydrone.
- Schank, Kurt,Lieder, Robert,Lick, Carlo,Glock, Rebecca
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p. 869 - 924
(2007/10/03)
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- On Ruhemann's Purple
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The 1H nmr spectrum previously reported for Ruhemann's Purple is shown to be inconsistent with the accepted structure of this material.The discrepancy with the reported 1H nmr spectrum is shown to be due to the presence of a major impurity, identified as hydrindantin.Spectra (1H nmr, 13C nmr, ir, uv-visible) of Ruhemann's Purple , its protonated analogue DYDA, and other ninhydrin relatives are reported, and structural conclusions are based on these spectral data.
- Wigfield, Donald C.,Buchanan, Gerald W.,Croteau, Stephen M.
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p. 201 - 205
(2007/10/02)
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- Reduction of Vicinal Tricarbonyl Compounds by Reduced Nicotinamide Adenine Dinucleotide Model and Electron-Transport Systems
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The reduction of vicinal tricarbonyl compounds such as alloxan (A) and ninhydrin (NY) with 1-benzyl-1,4-dihydronicotinamide (BNAH; NADH model) was investigated.In the reduction of A with BNAH, the radical anion (A-.Py+) of A as the 1-benzyl-3-carbamoylpyridinium salt and the dialuric acid (D) was obtained by one-electron and two-electron reduction,respectively.Similarly,hydrindantin (HDT) and 2-hydroxy-1,3-indandione (HID) were also afforded in the reduction of NY with BNAH.Further,the reductions of alloxantin (AT) and HDT with BNAH were performed to give D and HID,respectively.The reduction of lipoic acid (LA) and viologens (V2+) with BNAH, which could not be reduced without A or NY, proceeded smoothly in their presence,and they proved to be useful as mediators for catalytic reduction of LA and V2+.
- Endo, Takeshi,Okawara, Makoto
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p. 2663 - 2666
(2007/10/02)
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