Kinetic Model of the Decomposition of Sodium Hydroxymethanesulfinate in Aqueous Solution

A kinetic model of the decomposition of sodium hydroxymethanesulfinate (rongalite) in aqueous solution at an initial value of pH 7.9 was considered. This multistep reaction was found to include oxidation decomposition in a solution surface layer and bulk reactions both with and without the participation of oxygen. To evaluate the parameters of this model, it was modified over three time intervals. The adequacy of this model to experimental data supported the hypothesis on the catalytic effect of active sulfur in the decomposition of rongalite.     

Interaction of N,N'-Di(4-chlorophenyl)diimide 1,1'-Binaphtyl-4,4',5,5',8,8'-hexacarboxylic Acid with Thiourea Dioxide in Solution and Thin Film

Crystallography Reports - The reactions of interaction of N,N'-di(4-chlorophenyl)diimide 1,1'-binaphtyl-4,4',5,5',8,8'-hexa-carboxylic acid (cubogen red) with thiourea dioxide...     

Kinetics of Heterogeneous Reduction of Red-Brown Zh Vat Dye with Rongalite in the Absence of Diffusion Hindrance

The kinetics of heterogeneous reduction of red-brown Zh vat dye with formaldehyde sodium sulfoxylate (rongalite) was studied. The dye was reduced in the form of nonporous disk, which eliminates the effect of mass transfer on the reaction rate. The stages of the reduction mechanism and the reaction rate equations are proposed.     

Chemical relaxation in a viscous shock

We consider the flow of a nonequilibrium dissociating diatomic gas in a normal compression shock with account for viscosity and heat conductivity. The distribution of gas parameters in the flow is found by numerically solving the Navier-Stokes and chemical kinetics equations. The greatest difficulty in numerical integration comes from the singular points of this system at which the initial conditions are given. These points lead to instability of the numerical results when the problem is solved by standard numerical methods. An integration method is proposed that yields stable numerical results-continuous profiles of the distribution of the basic gas parameters in the shock are obtained.We consider steady one-dimensional flow in which the gas passes from equilibrium state 1 to another equilibrium state 2, which has higher values for temperature, density, and pressure. Such a flow is termed a normal compression shock.The parameter distribution in normal shock for nonequilibrium chemical processes has usually been calculated [1–3] without account for the transport phenomena (viscosity, heat conduction, and diffusion). The presence of an infinitely thin shock front perpendicular to the flow velocity direction was postulated. It was assumed that the flow is undisturbed ahead of the shock front. The gas parameters (velocity, density, and temperature) change discontinuously across the shock front, but the gas composition does not change. The composition change due to reactions takes place behind the shock front. The gas parameter distribution behind the front was calculated by solving the system of gasdynamic and chemical kinetics equations using the initial values determined from the Hugoniot conditions at the front to state 2 far downstream.Several studies (for example, [4, 5]) do account for transport phenomena in calculating parameter distribution in a compression shock, but not for nonequilibrium chemical reactions. These problems are solved by integrating the Navier-Stokes equations continuously from state 1 in the oncoming flow to state 2 downstream.We present a solution to the problem of normal compression shock in nonequilibrium dissociating oxygen with account for viscosity and heat conduction using the Navier-Stokes equations.     

Thermodynamic activation parameters of hindered rotation of the CF<Subscript>3</Subscript> group in the 4-nitrophenyltrifluoromethylsulfone radical anion in DMF

The thermodynamic activation parameters of hindered rotation of the CF₃ group in the 4-nitrophenyltrifluoromethylsulfone radical anion in DMF were determined from the temperature dependence of the EPR line widths and spin density distributions calculated by the U-B3LYP method in the 6-31+G* basis set. In the range 293 > T > 199 K, the activation energy of hindered rotation E _F depends on the temperature and changes in the range 9.67 < E _F < 18.95 kJ·mol^?1; the changes in the activation enthalpy and entropy are 7.23 < ΔH ^≠ < 17.30 kJ·mol^?1 and ?53.45 < ΔS ^≠ < ?11.37 J·(mol·K)^?1, respectively. Based on the suggested method for evaluating the inner product of the g tensor and the tensor of anisotropic hfi with the ¹⁴N nucleus for nitrobenzene radical anions in the liquid state we calculated the correlation time and determined the activation energy of rotational diffusion of the 4-nitrophenyltrifluoromethylsulfone radical anion in DMF, E _r = 20.175±0.54 kJ·mol^?1.     

Kinetics of Liquid-Phase Redox Reactions Involving Hydroxy- and Aminoalkanesulfinates

The mechanisms and kinetics of practically important redox reactions proceeding under the action of hydroxy- and aminoalkanesulfinates are analyzed. The general features allowing forecasting of the rates of reactions involving the above reducing agents are elucidated.