Volumetric Properties of Aqueous 2-Chloroethanol Solutions and Volumes of Transfer of Some Amino Acids and Peptides from Water to Aqueous 2-Chloroethanol Solutions

Densities and apparent molar volumes of aqueous 2-chloroethanol were determined at temperatures from 15.0 to 34.4°C using digital densimetry. The results of the volumetric measurements have been used to calculate the following thermodynamic quantites at 25°C: V ₂ ^o = 55.05 ± 0.02 cm³-mol^–1, (V ₂ ^o/T)_p = 0.01486 ± 0.00318 cm³-K^–1-mol^–1, and (² V ₂ ^o/T ²)_p = 0.02972 ± 0.00318 cm³-K^–2-mol^–1. Partial molar volumes of transfer from water to 1 mol-dm^–3 2-chloroethanol have also been determined for L-glycine, L-alanine, L-serine, L-glutamic acid, and L-aspartic acid at 35.0°C. The transfer results have been explained in terms of the nature of the interactions of the groups in the solute and solvent. Hydration numbers of L-glycine and L-alanine have also been calculated in aqueous 2-chloroethanol.     

Kinetics of the Effect of Some Bidentate Amino Acid Ligands in the Oxidation of Lactic Acid by Chromium(VI)1

The oxidation of lactic acid by Cr(VI) under acidic conditions is catalyzed by bidentate amino acid ligands such as glycine, alanine, aspartic acid and hydroxyproline. Catalysis is a function of [L]/[Cr(VI)] ratio and acidity. Pyruvic acid and acetaldehyde in a ratio of 2 : 1 are obtained as oxidation products in both uncatalyzed and catalyzed oxidation. This supports the previous understanding of the oxidation of -substituted carboxylic acids. Cromium(V) and chromium(VI) behave similarly in a C–H bond rupture (Rocek, J. and Radkowsky, A.E., J. Am. Chem. Soc., 1973, vol. 95, p. 7123), whereas Cr(IV) is responsible for C–C bond cleavage products (Wiberg, K.B. and Schafer, H., J. Am. Chem. Soc., 1969, vol. 91, p. 927).     

Studies of synthesis, structural features of Cu(I) thiophene-2-thiocarboxylates and unprecedented desulfurization of Cu(II) thiocarboxylate complexes

Thiophene-2-thiocarboxylate complexes of Cu(I), [(Ph(3)P)(2)Cu(SCOth)] (1) and H[(Ph(3)P)(2)Cu(SCOth)(2)] (2) (where th = thiophene) were synthesized and characterized structurally by X-ray crystallography. Electronic absorption and emission spectral properties of the two compounds have been studied. Cu(II) complexes, [(TMEDA)Cu(SCOth)(2)] (3b) and [(Phen)Cu(SCOth)(2)] (4a) (where TMEDA = tetramethylethylenediamine; Phen = 1,10-phenanthroline) were prepared and characterized by spectroscopic measurements. 3b and 4a underwent desulfurization under ambient conditions readily yielding the corresponding carboxylate complexes [(TMEDA)Cu(O(2)Cth)(2)] (3a) and [(Phen)Cu(O(2)Cth)(2)·H(2)O] (4b). 3a and 4b have been characterized crystallographically.     

Iron(III) complexes of a tetradentate tripodal ligand N,N′,N″-tris (2-benzimidazolyl-methyl)amine

Summary Fe^III complexes of a tetradentate ligand with pendant benzimidazolyl groups have been synthesized and characterized. Room temperature Mössbauer spectra depict a quadruple split doublet in the case of NO _inf3 ^p– as co-ligand, while a nearly symmetrical one line spectrum is obtained for complexes with Cl^–as co-ligand. The isomer shift values are towards the lower end of the range found for other high spin Fe^III complexes. ¹H-n.m.r. spectra of the complexes reveal relatively broad linewidths with large isotropic shifts. Paramagnetically shifted resonances are observed in the range of –10.0–+70.0 p.p.m.Author to whom all correspondence should be directed.     

Synthesis,Structures, and Fungitoxicity of Novel Organophosphorus Compounds

Abstract

A series of biologically active organophosphorus compounds have been synthesized by the reactions of O,O-diethylchlorophosphate with Schiff bases derived from 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-oxadiazole and salicylaldehyde/2-hydroxyacetophenone. The compounds have been characterized on the basis of analyses and spectral (IR, ¹H, ¹³C NMR) data. Fungicidal activities of these derivatives against Colletotrichum falcatum, Fusarium oxysporum, and Curvularia pallescence have been evaluated. All compounds showed moderate to significant antifungal activity.     

Efficient and Green Syntheses of 12-Aryl-2,3,4,12-tetrahydrobenzo[b]xanthene-1,6,11-triones in Water and Task-Specific Ionic Liquid

Facile and convenient one-pot cascade/tandem approaches for the syntheses of privileged medicinal scaffolds, 12-aryl-2,3,4,12-tetrahydrobenzo[b]xanthene-1,6,11-trione derivatives, have been reported under extremely mild reaction conditions using a catalytic amount of H₂SO₄ in water or in the presence of the acidic ionic liquid bmim[HSO₄], which could be recycled.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Fluorescent azophenol-quinazoline dyad as multichannel reversible pH indicator in aqueous media: an innovative concept on diazo based dyads

A novel azophenol-quinazoline dyad 1 has been designed, synthesized and demonstrated as an efficient reversible multichannel pH indicator through distinct signalling in aqueous media. Owing to the competence between highly fluorescent quinazoline moiety and a well known fluorescence quencher diazo group, dyad 1 is moderately fluorescent in nature. Under acidic conditions 1 displays diverse fluorogenic changes (blue emission at pH 4.25; green at pH 1.80) while under basic condition (pH 11.80) chromogenic changes were observed.     

Nanofibrous polyaniline thin film prepared by plasma‐induced polymerization technique for detection of NO2 gas

A nanofibrous polyaniline (PANI) thin film was fabricated using plasma‐induced polymerization method and explored its application in the fabrication of NO₂ gas sensor. The effects of substrate position, pressure, and the number of plasma pulses on the PANI film growth rate were monitored and an optimum condition for the PANI thin film preparation was established. The resulting PANI film was characterized with UV–visible spectrophotometer, FTIR, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The PANI thin film possessed nanofibers with a diameter ranging from 15 to 20 nm. The NO₂ gas sensing behavior was studied by measuring the change in electrical conductivity of PANI film with respect to NO₂ gas concentration and exposure time. The optimized sensor exhibited a sensitivity factor of 206 with a response time of 23 sec. The NO₂ gas sensor using nanofibrous PANI thin film as sensing probe showed a linear current response to the NO₂ gas concentration in the range of 10–100 ppm. Copyright © 2009 John Wiley & Sons, Ltd.     

Theoretical investigation on the kinetics and thermochemisty of H-atom abstraction reactions of 2-chloroethyl methyl ether (CH<Subscript>3</Subscript>OCH<Subscript>2</Subscript>CH<Subscript>2</Subscript>Cl) with OH radical at 298 K

Kinetics and thermochemistry of the H-atom abstraction reaction of CH₃OCH₂CH₂Cl with OH radical have been carried out using dual level of methods. Initially, geometry optimization and frequency calculations are performed at M06-2X/6-31+G(d, p) level of theory, and energetic calculations are further refined using CCSD(T)/6-311++G(d, p) level of theory in order to characterized all stationary points on potential energy surface (PES). The result shows that H-atom abstraction from –OCH₂ site of CH₃OCH₂CH₂Cl is dominant path. The rate constants are calculated using canonical transition state theory at 298 K, which are found to be in good agreement with the experimental data. We have presented the standard enthalpies of formation for CH₃OCH₂CH₂Cl and the radicals generated during the H-atom abstraction using group-balanced isodesmic reactions scheme. The atmospheric lifetime of title molecule is also calculated.