Partial molar volume of paracetamol in water, 0.1 M HCl and 0.154 M NaCl at T = (298.15, 303.15, 308.15 and 310.65) K and at 101.325 kPa

The apparent molar volume of paracetamol (4-acetamidophenol) in water, 0.1 M HCl and 0.154 M NaCl as solvents at (298.15, 303.15, 308.15 and 310.65) K temperatures and at a pressure of 101.325 kPa were determined from the density data obtained with the help of a vibrating-tube Anton Paar DMA-48 densimeter. The partial molar volume, V_m, of paracetamol in these solvents at different temperatures was evaluated by extrapolating the apparent molar volume versus molality plots to m = 0. In addition, the partial molar expansivity, E^°, the isobaric coefficient of thermal expansion, α_p, and the interaction coefficient, S_v, have also been computed. The expansivity data show dependence of E^° values on the structure of the solute molecules.     

Clerodane diterpenoids from Ajuga bracteosa Wall

The whole plant of Ajuga bracteosa afforded five compounds including one new clerodane diterpenoid designated as Bracteonin-A (1) 6alpha-acetoxy, 15 (R&S)-methoxy, 18-(4'-hydroxy, 3'-beta-methyl, 3'-alpha-acetoxy, butyryloxy) neoclerodane. The other compounds identified were 14,15-dihydroajugapitin, 14-hydro-15-hydroxy ajugapitin, beta-sitosterol, and stigmasterol. The structural elucidation was carried out by spectroscopic techniques.     

Effects of alkaline earth metal stearates on the dehydrochlorination of poly(vinyl chloride)

The thermo non-oxidative degradation of PVC and the effects of alkaline earth metal (Be, Mg, Ca, Ba) stearates were studied by thermogravimetry in the temperature range 150 to 500°C. The alkaline earth metal stearates were observed effectively reduce the dehydrochlorination of PVC. The synergistic effects of combinations of these salts with lead stearate were also studied and are discussed. Kinetic parameters such as the activation energy, order of reaction and Arrhenius factor were calculated by the Coats and Horowitz methods. The results showed that these metal stearates increase the activation energy required for the dehydrochlorination of PVC.     

An Efficient and Selective Solid State Oxidation of Thiols to Disulfides with Quinolinium Fluorochromate on Silica Gel

Summary. Various kinds of aliphatic (cyclic and acyclic), aromatic, and heterocyclic thiols are converted into the corresponding disulfides by quinolinium fluorochromate (QFC) on silica-gel in excellent yields. Selective oxidation of thiols in the presence of sulfides is also achieved under solid phase conditions.     

Determination of aliphatic amines in water by gas chromatography using headspace solvent microextraction

The possibility of applying headspace microextraction into a single drop for the determination of amines in aqueous solutions is demonstrated. A 1 μl drop of benzyl alcohol containing 2-butanone as an internal standard was suspended from the tip of a micro syringe needle over the headspace of stirred sample solutions for extraction. The drop was then injected directly into a GC. The total chromatographic determination was less than 10 min. Optimization of experimental conditions (sampling time, sampling temperature, stirring rate, ionic strength of the solution, concentration of reagents, time of extraction and organic drop volume) with respect to the extraction efficiency were investigated and the linear range and the precision were also examined. Calibration curves yielded good linearity and concentrations down to 2.5 ng ml⁻¹ were detectable with R.S.D. values ranging from 6.0 to 12.0%. Finally, the method was successfully applied to the extraction and determination of amines in tap and river water samples. This system represents an inexpensive, fast, simple and precise sample cleanup and preconcentration method for the determination of volatile organic compounds at trace levels.     

Mössbauer spectroscopic study of FeAl1−x Co x

We report the results of a Mössbauer study of the alloy sytem FeAl_1?x Co _x forx ≥ 0.3 at temperatures down to 83 K. Magnetic splitting is observed forx ≥ 0.35 at all temperatures. However, forx=0.3, no splitting is observed at room temperature, and superparamagnetic behavior occurs at LN₂ temperature. The magnetically split spectra are fitted each with a distribution of hyperfine fields and the average hyperfine field \(\bar B_{hf} \) as a function of temperature is obtained. The variation of \(\bar B_{hf} \) withT is explained using the model of magnetic clusters with collective magnetic excitations from which the saturation hyperfine field and the magnetic anisotropy energy for these clusters are obtained. Also, the results are discussed using the model of random atomic distributions, and the agreement between the calculated and the experimentally obtained distributions of hyperfine fields is found improve asx increases.     

Calamitic liquid crystals of 1,2,3-triazole connected to azobenzene: synthesis,characterisation and anisotropic properties

Azobenzene-based calamitic liquid crystals, 4-((4-(4-methoxymethyl-1,2,3-triazol-1-yl)phenyl)diazenyl)phenylalkanoates have been isolated and their structures were characterised. The structure–property correlation with respect to the different alkanoyloxy terminal chain (–COOC_nH_2n+1 where n adopts odd numbers ranging from 3 to 15) has also been given attention in the present study. In this series, all compounds exhibit smectogenic properties. The lower homologues shows enantiotropic SmA phase as well as monotropic SmC phase. The higher homologues exhibit homeotropic alignment of smectic phases. These compounds possess very high anisotropic inclination in which the mesomorphic region covers nearly 80°C.     

Clay Supported Bis-(trimethylsilyl)-chromate: An Efficient Reagent for Oxidative Deoximation

 A convenient method for the direct conversion of oximes to carbonyl compounds upon treatment with clay supported BTSC under classical heating as well as microwave irradiation in a solvent-free system is described.