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11.
An efficient method for the synthesis of enantiomerically pure (R)-phenylephrine hydrochloride 1 is described using a Sharpless asymmetric dihydroxylation as the key step. 相似文献
12.
Santosh K. Upadhyay Mahesh C. Agrawal 《Monatshefte für Chemie / Chemical Monthly》1979,110(2):413-418
Osmium(VIII) catalysed oxidation of lysine by ferricyanide in excess ferrocyanide shows a complex kinetics. The order in lysine falls, from 1 to 0 while that in ferricyanide increases from 0 to 2 with large increase in lysine concentration. The rates were directly proportional to [Os(VIII)] and {Const.+[Fe(CN)
6
4
]}. A suitable mechanism is proposed and discussed.
Oxidation von lysin mittels ferricyanid in der gegenwart von osmium(VIII)
Zusammenfassung Die von Os(VIII) katalysierte Oxidation von Lysin mit Ferricyanid in überschüssigem Ferrocyanid zeigt eine komplexe Kinetik. Bei starker Steigerung der Lysinkonzentration fällt die Ordnung bezüglich Lysin von 1 auf 0, während bezüglich Ferricyanid eine Erhöhung, von 0 auf 2 festzustellen ist. Die Geschwindigkeitskonstanten waren direkt proportional zu [Os(VII)] und {Const.+[Fe(CN) 6 4 ]}. Es wird ein möglicher Mechanismus vorgeschlagen und diskutiert.相似文献
13.
We report herein the effect of palladium on the redox electrochemistry of ferrocene monocarboxylic acid encapsulated within an organically modified sol-gel glass network (ORMOSIL). It has been found that amount of palladium and its geometrical distribution significantly alter the redox electrochemistry of FcMCA. The geometrical distribution of palladium has been controlled by two methods: (i) palladium is allowed to link within nanostructured network of the ORMOSIL which was subsequently availed from the reactivity of palladium chloride and trimethoxysilane; (ii) palladium powder is encapsulated together FcMCA thus allowing the presence of palladium within the nanoporous domain. The content of palladium is varied by controlling the reaction dynamics of palladium chloride and trimethoxysilane interaction. For this we initially allowed to trigger hydrolysis, condensation and poly-condensation of trimethoxysilane and dimethyldiethoxysilane in acidic medium and subsequently partially dried ORMOSIL film was allowed to interact with palladium chloride. Even with partially dried ORMOSIL derived from trimethoxysilane and dimethyldiethoxysilane undergoes rapid interaction with palladium chloride and the transparent color of ORMOSIL changed to a black colour due to the formation of palladium silicon linkage. The palladium-silicon linkage has been identified by NMR, UV-VIS and transmission electron spectroscopy. The electrochemistry of FcMCA encapsulated within such an ORMOSIL matrix has been studied. Excellent redox electrochemistry of ferrocene monocarboxylic acid having peak potential separation tending to 0 for a multilayered electrode was investigated. The palladium content has been found to affect the redox electrochemistry of ferrocene as well as electrocatalytic efficiency of new ORMOSIL material. The electroanalysis of NADH is reported. The modified electrode is very sensitive to NADH with lowest detection limit of < 1 microM. 相似文献
14.
Submerged culture fermentation studies were carried out in batch mode for optimizing the environmental parameters and carbon
source requirement by Pseudomonas elodea for the production of gellan gum. The maximum production of gellan gum was obtained with 16-h-old culture and 8% inoculum
at 30°C and pH 7.0 after 52 h of incubation (6.0 g/L). Of the various carbon sources tested, 2% sucrose, glucose, and soluble
starch yielded considerably high amounts of gellan. Studies on the concentration of various carbohydrates on gellan gum production
indicated that the optimum concentration of glucose and starch was 3%, whereas for sucrose it was 4%. The addition of glucose
in the medium above 3% had a detrimental effect on gellan yield. The investigation of intermediate two-step addition of glucose
under identical conditions of fermentation showed an enhanced production of gellan (8.12 g/L) as compared with the control
(6.0 g/L). To optimize the recovery of gellan from fermented broth, different solvents were tested for precipitation of gellan
gum. Among the various solvents tested, tetrahydrofuran gave better recovery of gellan (82%) as compared with the conventional
solvent isopropanol (49%). 相似文献
15.
Summary The kinetics of oxidation of aldoses, namely xylose, arabinose, galactose and glucose, by CeIV have been studied in HClO4 + H2SO4 medium and in the presence of PdII. The reactions exhibit a first order rate dependence with respect to oxidant. The rate is inversely dependent on the [HSO
inf4
sup–
][H+] ratio. The order of reaction with respect to aldose decreases at higher [aldose]. Due to the formation of a complex between CeIV and PdII, a retarding effect of [PdII] on the rate of disappearance of [CeIV] has been observed. A mechanism consistent with the observed kinetic data is proposed. 相似文献
16.
Anil K. Awasthi Santosh K. Upadhyay 《Monatshefte für Chemie / Chemical Monthly》1985,116(6-7):729-736
The kinetics of ruthenium(III) catalyzed oxidation of formaldehyde and acetaldehyde by alkaline hexacyanoferrate(III) has been studied spectrophotometrically. The rate of oxidation of formaldehyde is directly proportional to [Fe(CN)
3–
6
] while that of acetaldehyde is proportional tok[Fe(CN)
3–
6
]/{k +k[Fe(CN)
3–
6
]}, wherek, k andk are rate constants. The order of reaction in acetylaldehyde is unity while that in formaldehyde falls from 1 to 0. The rate of reaction is proportional to [Ru(III)]
T
in each case. A suitable mechanism is proposed and discussed.
Die Kinetik der Ru(III)-katalysierten Oxidation von Formaldehyd und Acetaldehyd mittels alkalischem Hexacyanoferrat(III)
Zusammenfassung Die Untersuchung der Kinetik erfolgte spektrophotometrisch. Die Geschwindigkeitskonstante der Oxidation von Formaldehyd ist direkt proportional zu [Fe(CN) 3– 6 ], währenddessen die entsprechende Konstante für Acetaldehyd proportional zuk[Fe(CN) 3– 6 ]/{k +k[Fe(CN) 3– 6 ]} ist, wobeik,k undk Geschwindigkeitskonstanten sind. Die Reaktionsordnung für Acetaldehyd ist eine erste, die für Formaldehyd fällt von erster bis zu nullter Ordnung. Die Geschwindigkeitskonstante ist in jedem Fall proportional zu [Ru(III)] T . Es wird ein passender Mechanismus vorgeschlagen.相似文献
17.
Kanchan Upadhyay Anupama Asthana Neetu Tiwari 《Research on Chemical Intermediates》2013,39(6):2629-2640
Two simple and sensitive spectrophotometric methods have been developed for analysis of the antipsychotic drug olanzapine in pharmaceuticals. Method A is based on liberation of iodine by reaction between the drug and potassium iodate, followed by reaction with leuco crystal violet (LCV), the color of oxidized LCV being measured at 598 nm. Method B is based on oxidation of olanzapine with chloramine-T (CAT) in acidic medium, the unconsumed CAT being determined with rhodamine B, measuring the absorbance at 550 nm. Calibration graphs were linear over the ranges of 0.05–2.0 and 0.1–1.6 μg mL?1 olanzapine for method A and B, respectively. The molar absorptivity, Sandell’s sensitivity, detection limit, and quantitation limit were found to be 1.59 × 105, 0.00132, 0.038, and 0.117, respectively, for method A and 0.953 × 105, 0.00221, 0.064, and 0.192, respectively, for method B. The optimum conditions and other analytical parameters were evaluated. The proposed methods have been applied successfully for analysis of olanzapine in pure form and its dosage forms, and no interference was observed from common excipients present in pharmaceutical formulations. 相似文献
18.
19.
Anand Kumar Chaudhari Vipin Kumar Singh Abhishek Kumar Dwivedy Somenath Das Neha Upadhyay Akanksha Singh 《Natural product research》2020,34(5):745-749
AbstractThe chemical characterisation of Pimenta dioica essential oil (PDEO) revealed the presence of 50 components, amongst which α-Terpineol (30.31%) was the major component followed by β-Linalool (6.75%) and γ-Terpinene (4.64%). The oil completely inhibited the growth of aflatoxin B1 secreting strain Aspergillus flavus LHP-VS-8 and aflatoxin B1 production at 2.5?µL/mL and 1.5?µL/mL, respectively. The oil caused dose dependent reduction of methylglyoxal (an AFB1 inducer), enhanced leakage of Ca2+, Mg2+ and K+ ions and significantly reduced ergosterol content of fungal plasma membrane. During in situ experiments, PDEO exhibited complete protection of fumigated maize cob slices from fungal infestation without affecting seed germination. The chemically characterised PDEO is recommended as a plant based preservative and shelf life enhancer of food commodities by preventing fungal growth, AFB1 production and lipid peroxidation. This is the first report on PDEO as inhibitor of AFB1 secretion and methylglyoxal biosynthesis. 相似文献
20.
We present a necessary and sufficient condition for existence of a contractible, non-separating and non-contractible separating Hamiltonian cycle in the edge graph of polyhedral maps on surfaces. We also present algorithms to construct such cycles whenever it exists where one of them is linear time and another is exponential time algorithm. 相似文献