Validated Simultaneous High-Performance Thin-Layer Chromatographic Analysis of Ursolic Acid, β-Sitosterol,Lupeol and Quercetin in the Methanolic Fraction of Ichnocarpus frutescens

JPC – Journal of Planar Chromatography – Modern TLC - A high-performance thin-layer chromatography (HPTLC) method for the simultaneous quantitative determination and validation of...     

Barrel- and crown-shaped dodecanuclear copper(II) cages built from phosphonate, pyrazole, and hydroxide ligands

The reaction of Cu(ClO4)2. 6H2O with t-BuP(O)(OH)2 and 3,5-(CF3)2PzH in the presence of triethylamine afforded the dodecanuclear cage ([Et3NH]2[Cu12(mu-3,5-(CF3)2Pz)6(mu3-OH)6(mu-OH)3(mu3-t-BuPO3)2(mu6-t-BuPO3)3][t-BuPO2OH][C6H5CH3]2) (2). The molecular structure of this cage revealed that it possesses a barrel-shaped architechture. The cage structure is built by the cumulative coordination action of phosphonate, hydroxide, and pyrazolyl ligands. A similar reaction involving Cu(NO3)2. 3H2O, t-BuP(O)(OH)2, 3,5-dimethylpyrazole, and triethylamine afforded another dodecanuclear cage [Cu12(mu-DMPz)8(eta1-DMPzH)2(mu4-O)2(mu3-OH)4(mu3- t-BuPO3)4].3MeOH (3). The latter is crown-shaped and is built by the coordination of pyrazole, pyrazolyl, phosphonate, hydroxide, oxide, and methanol ligands. Both of the dodecanuclear cages are efficient nucleases in the presence of magnesium monoperoxyphthalate.     

Suppressed ion chromatography for monitoring chemical impurities in steam for geothermal power plants

A suppressed ion chromatography (IC) technique has been evaluated as a chemical monitoring tool for detecting major anions (F-, Cl-, NO3- and SO4(2-)) of condensed steam in geothermal power plants. It is shown that the suppressed IC technique provides a suitable means for preventing possible damage to generating equipment in the geothermal industry. An electrical conductivity detector (0.1 microS sensitivity) with an anion-exchange column (IonPac AS4A-SC), a micro-membrane suppressor (AMMS II), and an isocratic high-pressure pump system were successfully used for detecting low concentrations of inorganic anions. Method detection limits for the anions of interest were <0.184 mg/L. Details of the IC methodology as well as some experimental results obtained during its application for the chemical monitoring of geothermal steam pipes are also described.     

Kinetics of the Ru(III) catalyzed oxidation of formaldehyde and acetaldehyde by alkaline hexacyanoferrate(III)

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.

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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.

     

Productive chloroarene C-cl bond activation: palladium/phosphine-catalyzed methods for oxidation of alcohols and hydrodechlorination of chloroarenes

The palladium/phosphine-catalyzed productive chloroarene C-Cl bond activation provides general, efficient, and functional group friendly methods for the selective oxidation of alcohols and the hydrodechlorination of chloroarenes.     

Effect of hydrothermal aging on NOx reduction performance for Sb–V–CeO2/TiO2 catalyst

Research on Chemical Intermediates - Herein, we investigated the NOx reduction performance of Sb–V–CeO2/TiO2 (SbVCT) catalyst subjected to hydrothermal aging, where 6 vol% of H2O was...     

Comparative study of volatile oil compositions of two Plectranthus species from northern India

The leaf and inflorescence essential oils of Plectranthus rugosus Wall. (syn. Rabdosia rugosa Wall.) and Plectranthus incanus L. (syn. Plectranthus mollis L.), which grow wild in Uttarakhand, India, were analysed and compared by capillary gas chromatography and gas chromatography-mass spectrometry. The analysis led to the identification of 43 constituents, forming 89.5-93.6% of the total oil compositions. Both leaf and inflorescence oil of P. rugosus were dominated by sesquiterpene hydrocarbons (71.8%, 71.7%) represented by β-caryophyllene (36.2%, 29.8%), germacrene D (25.2%, 28.2%) and α-humulene (6.6%, 8.6%) as the major constituents. Conversely, the leaf and inflorescence oil of P. incanus were dominated by monoterpenoids (74.4%, 65.8%) with piperitenone oxide (44.2%, 38.5%), piperitone (8.6%, 12.2%) and terpinolene (14.5%, 10.2%) as major constituents. Piperitenone oxide, piperitone, cis- and trans-piperitols and trans-piperitol acetate were the marker constituents in P. incanus, which were not noted in the essential oil of P. rugosus.     

Reactions of fluorinated acid anhydrides, (CF3CO)2O, (CF3SO2)2O and (FSO2)2O, with organometallic substrates of group 15 (As, Sb and Bi)

(C₆H₅)₃MX₂ (M = As, Sb; X = OCOCF₃ and M = Sb, Bi; X = SO₃F, SO₃CF₃) compounds prepared by the interaction of triphenylmetal(V) substrates with (CF₃CO)₂O, (CF₃SO₂)₂O and (FSO₂)₂O have been characterized by molecular weight determination, elemental and spectroscopic (IR, ¹H and ¹⁹F NMR, mass) analyses.     

All-trans-N-retinylidenetryptamine Schiff base in surfactant solubilized water pools in heptane—a fluorescence study

All-trns-N-retinylidenetryptamine Schiff base was incorporated into aerosol-OT (AOT, sodium bis(2-ethylhexyl)sulphosuccinate)/heptane reverse micelles. This micellar system was used as a model to study the retinal-tryptophan interactions in retinal proteins. The retinylidene Schiff base remains stable in the presence of reverse micelle-solubilized water pools. Partition coefficient and microviscosity measurements show that the Schiff base is located in the micellar interphase. The results are discussed in terms of the interaction between the retinylidene chromophore and the active site environment of rhodopsin and bacteriorhodopsin. In the present model, the quencher and emitting units are covalently attached, and are separated by two carbon spacer units. The fluorescence emission data obtained for the micelle-intercalated Schiff base chromophore are compared with the fluorescence of the native protein and intermediates in the photochemical cycle of bacteriofhodopsin. A comparison of the data obtained for tryptamine and the Schiff base with the results available for bacteriorhodopsin and bacterioopsin reveals that there is a large degree of quenching on intercalation of the retinylidene chromophore in the vicinity of the fluorophore. Evidence provided by this model suggests that energy transfer to retinal can occur from tryptophan residues located in the retinal pocket in the native protein. Thus the retinylidene unit can act as a quencher of the energy of tryptophan, the nature and extent of which may depend on the conformation and relative orientation of the protein-bound fluorophore.     

Volatile constituents of Origanum vulgare L., 'thymol' chemotype: variability in North India during plant ontogeny

Essential oils derived from six different phenophases, namely early vegetative stage, late vegetative stage, early flowering stage, full flowering stage (FFS), late flowering stage and seed shattering stage of Origanum vulgare L. grown in Kumaon region of Uttarakhand, India were investigated by GC and GC-MS. A total of 38 constituents, representing 97.4-99.7% of the total oil composition, were identified. Major components of oils were thymol (40.9-63.4%), p-cymene, (5.1-25.9%), γ-terpinene (1.4-20.1%), bicyclogermacrene (0.2-6.1%), terpinen-4-ol (3.5-5.9%), α-pinene (1.6-3.1%), 1-octen-3-ol (1.4-2.7%), α-terpinene (1.0-2.2%), carvacrol (<0.1-2.1%), β-caryophyllene (0.5-2.0%) and β-myrcene (1.2-1.9%). Thymol, terpinen-4-ol, 3-octanol, α-pinene, β-pinene, 1,8-cineole, α-cubebene and (E)-β-ocimene were observed to be higher during FFS. The study showed that plant stage had a significant effect on the essential oil content and composition of O. vulgare grown in the hilly tracks of Northern India.