Volume changes on mixing of isomeric butanols withn-heptane have been determined at 25°C and that of tertbutanol at 26°C. All the four systems show a positive excess volume throughout concentration range. The excess volumes have been found to vary in the order of tert >sec >iso >n-butanols. The order of the excess volume has been attributed to breaking of hydrogen bonds of associated species of alcohol by dilution withn-heptane and more random distribution ofn-heptane molecules.

The excess free energy, enthalpy and entropy of mixing of isomeric butanols withn-heptane determined at 55°C were found to be positive due to the breaking of hydrogen bonds. In the case ofn-butanol the excess entropy was negative beyond the concentration rangex₂>0.4. The data on excess free energy and enthalpy of mixing could be well represented by the Redlich-Kister equation. An attempt to calculate excess enthalpy from temperature dependence of excess free energy for iso and sec-butanol systems has been made. The results are discussed in the light of the idealised model.

During the last 5 years, since its first application to biomolecules, two-dimensional nuclear Overhauser effect (2DNOE) has become an extremely powerful technique for assignment ofNMR spectra and for elucidation of conformation of biomolecules in solution.

The methodology of the 2DNOE technique, its recent developments and its applications to proteins and oligonucleotides are briefly reviewed.

Simple equations are presented for predicting density, compressibility and expansivity of aqueous mixed electrolyte solutions. These equations do not require any empirical parameter. Equations are tested upto very concentrated solutions and at various temperatures. It is essential to know the properties of single electrolyte solutions for predicting properties in mixtures. Predicted properties are in excellent agreement with experimental data.

The distribution of nickel and cobalt species has been computed, based on the pH-dependent model of Zirino and Yamamoto. The media used in the pH range of 7 to 9 are natural waters like fresh water, sea water and a mixture of them at different compositions, at 25°C temperature and 1 atm pressure. In fresh water, both nickel and cobalt dominate as free cations at lower pH, and as carbonato complexes at higher pH. In sea water, chloro complexes are significant. In mixtures of the two kinds of water, as might be found in a totally mixed estuary, chloro complexes are important, varying slowly with pH. Sea water plays an important role in complexation. The present results are in excellent agreement with experimental data obtained by the resin exchange method.

A new method of mapping molecular electrostatic potentials using a dipole of arbitrary length and strength has been developed. The dipole is allowed to move on a geometrical surface enclosing the molecule under study such that the closest distance of approach (CDA) between the two species is fixed. Potential maps of water, formaldehyde and ethylene epoxide molecules have been studied by this approach for CDA values of 2 and 5 A. Experimental geometries for the molecules and net charge distributions obtained by the MNDO molecular orbital method were used in the calculations. Dipole potential maps obtained by the present method are compared with those obtained by the prevalent monopole mapping method. The two approaches broadly predict the same sites for potential minima in the molecules studied. The present dipole maps are however more informative, especially with regard to electric field directions, than the monopole maps, and it has been shown that this additional information is very useful.

Excess molar volumes$$V_m^E $$ and viscosities (η) have been measured as a function of composition for binary liquid mixtures of 1-propanol, C₃H₇OH, with diethylene glycol diethyl ether(bis(2- ethoxyethyl)ether), C₂H₅(OC₂H₄)₂OC₂H₅, and diethylene glycol dibutyl ether (bis(2-butoxyethyl)ether), C₄H₉(OC₂H₄)₂OC₄H₉, at 288.15, 298.15, and 308.15 K and at atmospheric pressure. The excess volume results included the following mixing quantities at all range of concentrations and at equimolar concentrations: α, volume expansivity;$$(V_m^E /\partial T)p,$$, and$$(\partial H^E /\partial P)_T $$ at 298.15 K. The obtained results were then compared with the calculated values by using the Flory theory of liquid mixtures. The theory predicts the α values rather well, while the calculated values of$$(V_m^E /\partial T)p,$$ and$$(\partial H^E /\partial P)_T $$ show variation with alkyl chain length of the polyether. The results are discussed in terms of order or disorder creation. From the viscosity data, deviations in viscosity (Δη) have been calculated. These values are negative over the entire range of composition. The results for$$V_m^E $$, and Δη are discussed in terms of interaction between components

The Kirkwood-Buff (K-B) integrals play an important role in characterizing the intermolecular interactions in liquid mixtures. These are represented by the K-B parameters, $G_{\text{AA}}$, $G_{\text{BB}}$, and $G_{\text{AB}}$, which reflect correlation between like-like and like-unlike species in the mixture. The K-B integrals of binary mixtures of acetonitrile (ACN) with formamide (FA), N,N-dimethylformamide (DMF), N-methylacetamide (NMA) and N,N-dimethylacetamide (DMA) at 298.15 K and at atmospheric pressure have been computed from the experimental data of ultrasonic speed and density. We have used the similar inverse procedure (as proposed by Ben-Naim) to compute the K-B Parameters of the mixtures, in which thermodynamic information on mixtures such as partial molar volumes, isothermal compressibility, and experimental data of partial vapour pressures are used. A new route has been incorporated by using regular solution theory in the computation of excess free energy for obtaining the partial vapour pressures of binary liquid mixtures. The low values of excess entropy ($S^E \approx 0$) obtained for these mixtures indicate the applicability of regular solution theory to these mixtures. The results obtained regarding intermolecular interaction in all the four mixtures under study from this new procedure are in good agreement with those obtained from the trends exhibited by the excess functions of these mixtures.

Quinoline is one of the important class of heterocyclic compounds which have gained considerable importance because of its high pharmaceutical efficacy and broad range of biological activities such as anticancer, anti-malarial, anti-microbial and anti-asthmatic. As a consequence, the desire for new versatile andefficient route for the synthesis of quinoline scaffolds remains an active and growing area of interest both in academia and industry. However, developments of transition-metal catalyzed synthetic methods have witnessed a dominant position over the past few years for the synthesis of diverse range of complex heterocyclics containing quinoline scaffolds. This review specifically provides an overview of the literature available on the transition–metal catalyzed synthetic methodologies for the synthesis of polysubstituted quinoline derivatives.

An expeditious, metal-free protocol has been demonstrated for the synthesis of isoxazolone derivatives using domino multi-component strategy. The envisaged methodology involves the L-valine promoted three-component cyclo-condensation reaction of alkylacetoacetates, hydroxylamine hydrochlorideand aldehydes in ethanol under reflux. The reaction proceeded to deliver the desired products in good to excellent yields (74–97%), exhibited good functional group tolerance and completed in less than 4 min with most of the substrates. High yields, short reaction time, noncorrosive organocatalyst, mild reaction conditions, clean reaction profiles and the absence of any tedious workup or purification are the beneficial features of this process. Moreover, quantum computational study has been performed at B3LYP/6-311G??(d, p) level toinvestigate the various DFT based molecular descriptors, HOMO–LUMO energy gap and electrostatic potential surface properties of the synthesized product