Volume 220, Issue 6

The imidazolium fluorochromate (IFC) oxidation of fifteen meta - and para -substituted anilines, in varying mole fractions of benzene in 2-methylpropan-2-ol as mixtures, in the presence of p -toluenesulfonic acid (TsOH) is first order in IFC and TsOH and zero order in substrate. The various thermodynamic parameters for the oxidation have been reported and discussed. The validity of the isokinetic relationship and various linear free energy relationships have been tested and discussed. The activation free energy data failed to correlate with macroscopic solvent parameters such as ε r and E T N . Correlation of Δ G # with Kamlet–Taft solvatochromic parameters (α, β and π*) suggests that the specific solute–solvent interactions play a major role in governing the reactivity.

Ultramicroelectrode voltammetric measurements have been used in the microemulsions of CTAB/1-butanol/heptane/water to calculate the diffusion coefficient which can reflect the structure transition of the microemulsions. It is found that with increasing water content of microemulsions, the apparent diffusion coefficient ( D app ) of the probe decreases monotonically with three transition points. The first two transition points indicate the change in the structure of microemulsions, that is from water in oil region to bicontinuous phase and then to oil in water region, while the third one differs from previous reports. The time resolved fluorescence quenching (TRFQ) technique has been carried out to obtain the aggregation number of the microemulsions in order to analyze the abnormal transition point. According to the TRFQ experiment, we find that the aggregation number of the microemulsion decrease with water content increasing between 50%–60%, and then tend to identical. These results suggest that the last transition point of the diffusion coefficient is because of the forces between oil droplets. The self-diffusion coefficient of oil droplet in the o/w region is calculated simultaneously. Based on these experimental results, we analyze the composition of the interface between oil and water.

Esterification of methyl alcohol with acetic acid catalysed by commercially available polymeric ion-exchange resins Amberlyst-15, Dowex 50W and Amberlite IR-120 was carried out in the temperature ranging between 323–338K. Mesh sizes and divinylbenzene contents had virtually no effect on the rate the data of which were correlated with a second-order homogeneous reaction. The samples were analysed with gas chromatography, refractometry and volumetry. The reproducibilities were the order of ±2.89%, ±5.07% and the order of ±6.58% respectively for the volumetric, chromatographic and refractometric methods.

FTIR spectroscopic study of butyl methacrylate (BMA) in different pure organic solvents were undertaken to investigate the solute–solvent interactions. The frequency of carbonyl stretching vibration ν(C=O) of BMA is correlated with the solvent properties such as the KBM parameter, the solvent acceptor number (AN), and the linear salvation energy relationships (LSER). The solvent-induced stretching vibration frequency shifts showed a better correlation with LSER parameters than AN. While no linear correlation between dielectric constants and the frequencies showed that the KBM relationship was unsuitable for this molecule. Also the solvent effect on the strength of hydrogen bond formation between free OH group of 1-butanol and C=O group of BMA is discussed in terms of local specific interaction between the solute and solvent.

The free energy of two different phases not in equilibrium at the limit of zero Kelvin must be different. This difference in free energy can be related to the enthalpy and entropy, resulting in a general relation between the transition entropy and enthalpy at the limit of zero Kelvin.

The characterization of the polycrystalline La 0.7 Ba 0.3 MnO 3-δ (LBM) and La 0.7 Ba 0.3 Mn 0.9 Li 0.1 O 3-δ (LBMLi) samples synthesized via the polymerized complex, sol-gel technique indicates the formation of cubic perovskite crystal structure of both samples by sintering at 900ºC for 2h. Substitution of Mn by Li having smaller ionic radius, leads to decrease the lattice constant and the cell volume which gives rise to a small shift and small intensity difference of the XRD patterns. A nanocrystalline structure of LBMLi with particles in the size range of 30–100nm was obtained. The temperature dependence of electrical conductivity and magnetic susceptibility of LBM and LBMLi were studied. The smaller electrical conductivity values and the calculated magnetic properties of Li substituted the Mn in LBM sample were investigated.

Phase equilibria in the molten system KF-K 2 NbF 7 -Nb 2 O 5 were investigated up to 20mol% of Nb 2 O 5 by thermal analysis and differential scanning calorimetry. In the binary and ternary systems oxofluoroniobate compounds are formed. They were evidenced by comparison of experimetal X-ray diffraction patterns with those in the international X-ray diffraction database (PDF-2). In the experimental compostion range the phase diagram of the molten KF-K 2 NbF 7 -Nb 2 O 5 system consists of five crystallisation fields corresponding to KF, K 3 NbF 8 , K 2 NbF 7 , K 2 NbO 3 F and K 3 NbOF 6 .

1 H and 13 C NMR chemical shifts have been determined to investigate the interactions of acetone with room temperature ionic liquids ([C 4 mim][PF 6 ], [C 6 mim][PF 6 ], [C 8 mim][PF 6 ] and [C 6 mim][BF 4 ]) at various acetone mole fractions. Changes in the chemical shifts of hydrogen and carbon atoms of the above systems indicated that hydrogen bonds were formed between the ring protons, the methyl and methylene next to the nitrogen of the ionic liquids and the carbonyl oxygen of the acetone molecules. The strength of hydrogen bond was found to be influenced not only by the type of the anion but also by the length of alkyl chain on the imidazolium ring of cations. At the same time, ab initio calculations have been performed to support the NMR results.