MICROWAVE ASSISTED OXIDATION OF BENZALDEHYDES UNDER SOLVENT-FREE CONDITION USING OXONE®/WET-ALUMINA

The solventless oxidation of benzaldehydes to carboxylic acids using oxone/wet-alumina under microwave irradiations is described.     

Solutions of Woods-Saxon Potential with Spin-Orbit and Centrifugal Terms through Nikiforov-Uvarov Method

In this study, the analytical solutions of the radial Schr¨odinger equation for the central Woods-Saxon potential together with spin-orbit interaction and centrifugal terms have been derived by using Nikiforov-Uvarov method. The energy eigenvalues and corresponding eigenfunctions of nucleons have been obtained for various values of n,l, and j quantum numbers. The obtained results using this method are in satisfactory agreement with available data in the special case.     

PEG–SO3H as a mild, efficient and green catalytic system for the synthesis of pyrazole derivatives in aqueous medium

A versatile, alternative and environmentally benign strategy for the synthesis of a series of pyrazoles has been successfully performed in water using PEG–SO₃H as an acidic catalyst. The products are obtained in high yield from the one-pot reaction procedure involving dicarbonyl compounds and hydrazines/hydrazides. This new method totally avoids the use of organic acids and toxic or expensive solvents in this reaction. The catalyst is waste-free, easily prepared, and efficiently re-used.     

Preparation of magnetic polyurethane rigid foam nanocomposites

Super paramagnetic Fe₃O₄@SiO₂ nanoparticle was incorporated into polyurethane rigid foams in order to prepare new corresponded magnetic nanocomposite foams via one-shot method. The core–shell-structured nanoparticles were prepared by sol–gel method and characterized by transmission electron microscopy, X-ray diffraction, as well as Fourier transform infrared spectroscopy techniques. Magnetic nanoparticles were used up to 3 % in the foam formulations and the samples prepared successfully. Thermal, mechanical, and magnetic properties of nanocomposites were studied and the results showed superior properties in comparison with pristine foams.     

Non-isothermal pyrolysis of used lubricating oil and the catalytic effect of carbon-based nanomaterials on the process performance

Pyrolysis is a commonly used method for the recovery of used lubricating oil (ULO), which should be kinetically improved by a catalyst, due to its high level of energy consumption. In this research, the catalytic effects of carbon nanotube (CNT) and graphene nanoplatelets on the pyrolysis of ULO were studied through thermogravimetric analysis. First, the kinetic parameters of ULO pyrolysis including activation energy were calculated to be 170.12 and 167.01 kJ mol^?1 by FWO and KAS methods, respectively. Then, the catalytic effects of CNT and graphene nanoplatelets on pyrolysis kinetics were studied. While CNT had a negligible effect on the pyrolysis process, graphene nanoplatelets significantly reduced the temperature of maximum conversion during pyrolysis from 400 to 350 °C, due to high thermal conductivity and homogenous heat transfer in the pyrolysis process. On the other hand, graphene nanoplatelets maximized the rate of conversion of highly volatile components at lower temperatures (<?100 °C), which was mainly due to the high affinity of these components toward graphene nanoplatelets and also the effect of nanoplatelets’ edges which have free tails and can bond with other molecules. Moreover, graphene nanoplatelets decreased the activation energy of the conversion to 154.48 and 152.13 kJ mol^?1 by FWO and KAS methods, respectively.

     

Surface stoichiometry and the initial oxidation of NiAl(110)

Selective oxidation of the surface of an ordered alloy requires redistribution of the atomic species in the vicinity of the surface. This process can be understood in terms of the formation and movements of point defects in the compound. On the basis of ab initio density-functional calculation we found both the creation of exchange defects near the NiAl surface and segregation of Ni vacancies to the top layer to be extremely favorable in the presence of oxygen. Scenarios for the initial oxidation of NiAl are suggested which demonstrate the appearance of an additional energy barrier on the Ni-rich side compared to the Al-rich side. The expulsion of Ni from the oxide layer as it forms is the driving force for its stability.     

Charge ordering in the TMTTF family of molecular conductors

Using one- and two-dimensional NMR spectroscopy applied to 13C spin-labeled (TMTTF)2AsF6 and (TMTTF)2PF6, we demonstrate the existence of an intermediate charge-ordered phase in the TMTTF family of charge-transfer salts. At ambient temperature, the spectra are characteristic of nuclei in equivalent molecules. Below a continuous charge-ordering transition temperature T(co), there is evidence for two inequivalent molecules with unequal electron densities. The absence of an associated magnetic anomaly indicates only the charge degrees of freedom are involved and the lack of evidence for a structural anomaly suggests that charge-lattice coupling is too weak to drive the transition.     

The pathway to reorientation in ammonium fluoride

Two alternative transition states for ammonium ion rotation in crystalline NH₄F have been characterised using ab initio calculations. In one all the cations rotate in phase, while in the other the rotating ions are isolated from each other by non-rotated ions. These two transition states are characterised by the cation displacement and changes in the bond lengths and bond angles within the ammonium ion. The pathway for passing over the barrier was investigated by low temperature molecular dynamics runs from each transition state. In both cases the order of events in passing from the ground state to the transition state is first cation displacement towards a neighbouring fluoride ion, secondly, lengthening of the NH bond pointing to this ion, and thirdly, rotation about this bond.