Experimental and Computational Study of the Thermal Decomposition of 3‐Methyl‐3‐buten‐1‐ol in m‐Xylene Solution

An experimental study of the thermal decomposition of a β‐hydroxy alkene, 3‐methyl‐3‐buten‐1‐ol, in m‐xylene solution, has been carried out at five different temperatures in the range of 513.15–563.15 K. The temperature dependence of the rate constants for the decomposition of this compound in the corresponding Arrhenius equation is given by ln k (s^?1) = (25.65 ± 1.52) ? (17,944 ± 814) (kJ·mol^?1)·T^?1. A computational study has been carried out at the M05–2X/6–31+G(d,p) level of theory to calculate the rate constants and the activation parameters by the classical transition state theory. There is a good agreement between the experimental and calculated rate constants and activation Gibbs energies. The bonding characteristics of reactant, transition state, and products have been investigated by the natural bond orbital analysis, which provides the natural atomic charges and the Wiberg bond indices. Based on the results obtained, the mechanism proposed is a one‐step process proceeding through a six‐membered cyclic transition state, being a concerted and slightly asynchronous process. The results have been compared with those obtained previously by us (Struct Chem 2013, 24, 1811–1816) for the thermal decomposition of 3‐buten‐1‐ol, in m‐xylene solution. We can conclude that in the compound studied in this work, 3‐methyl‐3‐buten‐1‐ol, the effect of substitution at position 3 by a weakly activating CH₃ group is the stabilization of the transition state formed in the reaction and therefore a small increase in the rate of thermal decomposition.     

Structural and Kinetic Aspects of Blood Plasma Protein Adsorption on the Surface of Hydrophobic Polymers

Abstract

Due to the wide use of polymers in medicine, researchers are required to solve a very important problem–to understand the interaction between materials of nonphysiological origin and the surrounding biological liquids, and tissues, particularly blood.     

The charge-density-wave transition in Lu5Ir4Si10 under uniaxial pressure

Abstract

An uniaxial pressure cell for low temperature use is described in detail. Then we present data of the electrical resistance of single crystals of Lu₅Ir₄Si₁₀, which is known to show a charge-density-wave transition around 83 K and to become superconducting near 3.8 K, both phenomena being anticorrelated under pressure. Since the CDW in Lu₅Ir₄Si₁₀ is a quasi one-dimensional phenomenon because of a chain-like structure, it responds to uniaxial pressure in a specific way.     

Magnetism in UNi2Ga3

We present the physical properties of the new intermetallic compound UNi₂Ga₃. This compound crystallizes in the hexagonal CaCu₅-structure, and bulk experiments (specific heat c _p, susceptibility X, magnetization M and resistivity ρ) indicate the system to undergo a magnetic transition at 9.5 K. No superconductivity is observed down to 50 mK. The magnetic transition in UNi₂Ga₃ closely resembles that of the incommensurably ordered state in the related heavy-fermion superconductor UNi₂Al₃. In addition, and independently from the conditions for sample preparation, we found indications for a considerable degree of lattice disorder, likely due to structural Ga/Ni disorder. We discuss our results, particularly the absence of superconductivity in UNi₂Ga₃, in comparison to UNi₂Al₃.     

Resistivity minima in quench-condensed films of palladium

We have found a shallow low temperature minimum in the electrical resistivity of thin quench-condensed Pd-films. The depth and temperature of this minimum depends upon the residual resistivity of the film.     

Thermopower of concentrated AuCr alloys

Measurements are presented of the thermopower of three concentrated $\text{Au}$Cr (0.9, 4.9 and 10.6 at.%Cr) alloys between 4 and 500°K. Considerable differences are observed in the thermopower compared with $\text{Au}$Fe alloys in a similar concentration range. Possible reasons for these differences are discussed in terms of current ideas on spin glasses and the pair model of Matho and Béal-Monod.     

Field-dependent thermal transport in the haldane chain compound NENP

We present a study of the magnetic field-dependent thermal transport in the spin S=1 chain material Ni(C(2)H(8)N(2))(2)NO(2)(ClO(4)) (NENP). The measured thermal conductivity is found to be very sensitive to the field-induced changes in the spin excitation spectrum. The magnetic contribution to the total heat conductivity is analyzed in terms of a quasiparticle model, and we obtain a temperature and momentum independent mean free path. This implies that the motion of quasiparticles is effectively three dimensional despite the tiny interchain coupling.