Radical reactions in organic crystals under pressure: Experiment and theory

The kinetics of radical transformations in gamma-irradiated dicarboxylic acid single crystals at a high pressure was studied by EPR spectroscopy. The activation parameters of the detachment of the hydrogen and reaction coordinates were determined. The dependence of the rate constant for the reaction on the pressure and crystal physical parameters was studied. The compression of crystals decelerated the detachment of hydrogen (the activation volumes were positive), and the rate-determining stage of the process was free volume fluctuations responsible for the approach of reagent active centers to each other and their arrangement and orientation along the reaction coordinate on the potential energy surface. The kinetic parameters of the reaction are closely related to the crystal characteristics such as the molar volume, compressibility, and thermal expansion coefficient. A theory describing this relation is suggested. Only part of the free volume was shown to be used for “reaction” fluctuations. The types of reagent motions responsible for the molecular organization of the transition state were identified.     

On Vectors whose Span Contains a Given Linear Subspace

Estimates are given for the product of the lengths of integer vectors spanning a given linear subspace.The first author was supported by FWF Austrian Science Fund, project M672.     

Synthesis of 1-(4-isopropenylphenoxy)-bromo-C2-C4-alkanes and application of their transformation products

Reaction of 4-isopropenylphenol with α,ω-dibromo-C₂-C₄-alkanes by the Willamson reaction in the presence of potassium iodide as promoter, aiming to synthesize the corresponding monobromosubstituted derivatives and to study their some chemical transformation. Optimal conditions to obtain 1-(4-isopropenylphenoxy)-2-bromoethane, 1-(4-isopropenylphenoxy)-3-bromopropane and 1-(4-isopropenylphenoxy)-4-bromobutane were found. The nitrogen-containing derivatives, inhibitors of a hydrosulfuric corrosion in the water-salt solutions, were obtained on the basis of the first two compounds. The derivatives involving multiple bond and ester-group were synthesized from the third compound. Their incorporation into the polystyrene chains in the process synthesis gives them plasticize properties.     

Synthesis and structure of [(p-phenylenedimethylene) Bis [diphenylphosphine]]-Bis[(acetylacetonato) carbonylrhodium(I) and its reaction product with inorganic azides,azidocarbonylbis (triphenylphosphine) rhodium(I)

Journal of Structural Chemistry -     

Visible and ultra-violet absorption spectra of aqueous solutions of transition metal salts affected by a high-voltage pulse electric discharge

The effect of a high-voltage pulse electric discharge (HVPED) on the electron spectra of CuSO₄, Ni(NO₃)₂, NiCl₂, CoSO₄, and Co(NO₃)₂ aqueous solutions is investigated. It is found that the salt system activation by HVPED can change the configurations of electron shells of molecular ions. It is stated that the processes of post-activation structural relaxation of CuSO₄/H₂O solution are rather long-term. It is shown that the character of the HVPED effect on the electron spectra of solutions significantly depends on the solution composition and the intensity of interparticle interactions therein.     

A concise approach to the epidithiodiketopiperazine (ETP) core

A novel approach to the epidithiodiketopiperazine nucleus, incorporating two three-component reactions in a four-step synthetic sequence is reported.     

Structure of 1,3-Bis-(3-benzoxazolonyl)-2-hydroxypropane

We have studied the ¹H NMR spectrum of the synthesized 1,3-bis(3-benzoxazolonyl)-2-hydroxypropane. The nature of the splitting of the signals in the spectrum and computer modeling indicate that free rotation is possible about all non-ring bonds in the compounds.