Effect of Nitrosodurene on Radical Copolymerization of Styrene with Acrylic Monomers

The effect of nitrosodurene as a source of stable nitroxyl radicals on radical copolymerization of styrene with methyl methacrylate and butyl acrylate was studied.     

Polymer synthesis in the presence of bis(cyclopentadienyl) derivatives of Group IV–VI transition metal dichlorides: a quantum chemical study of particular reaction stages

Key pathways of interaction between growing radicals of vinyl monomers and bis(cyclopentadienyl) derivatives of Group IV–VI transition metal dichlorides were studied by the BP86/6-31G(d) and B3LYP/LanL2DZ quantum chemical methods. Prospects for use of these organometallic compounds as chain growth regulators in controlled polymerization were assessed. The character of the interaction of the compounds studied with the growing radicals is mainly determined by the metal atom. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1690–1694, September, 2007.     

Quantum-chemical study of the singlet potential energy surface of the nitrene—dioxygen system

The potential energy surfaces of the HN—O₂ and PhN—O₂ systems were calculated by the MP2 and B3LYP methods. The mechanism of photooxidation of azides was refined. Photooxidation produces the nitrene—O₂ adducts with dioxaziridine and non-cyclic structures. The parameters of IR spectra of the adducts were calculated. The rearrangement of dioxaziridine to a nitro compound is likely a reason for chemiluminescence accompanying the photooxidation of azides.     

Dicyclopentadienyltitanium chlorides as regulators of free-radical polymerization of vinyl monomers

The free-radical polymerization of styrene and methyl methacrylate in the presence of dicyclopentadienyltitanium chloride and dicyclopentadienyltitanium dichloride has been studied. It has been shown that the process proceeds without autoacceleration up to high conversions and is characterized by a linear increase in molecular mass with conversion. On the basis of quantum chemical calculations and ESR spectroscopic data, a scheme describing the growth of polymer chains with participation of organotitanium compounds is proposed.     

Nitrene Adducts with Oxygen in the Photooxidation Reactions of Organic Azides

The photooxidation of organic azides and the photochemical reduction of nitro compounds include the formation of a common intermediate: the adduct of a nitrene with oxygen. The ground state of the adduct is singlet; the singlet–triplet gap is small and equals 80.2 or 56.7 kJ/mol for HNOO or C₆H₅NOO, respectively. Arguments for the involvement of singlet molecular oxygen, atomic oxygen, hydroxyl radicals, and dioxaziridines in these reactions were given.     

Efficiency of low-molecular-weight and high-molecular-weight alkoxyamines in the synthesis of polystyrene

Russian Chemical Bulletin - The influence of the structure of high-molecular-weight alkoxyamines (obtained in situ from C-phenyl-N-tert-butylnitrone and...     

Synthesis of (azidomethyl)phenylboronic acids

The synthesis of 2-, 3-, and 4-(azidomethyl)phenylboronic acids was carried out. The geometric and electronic structures were studied by quantum-chemical methods. The suggestion is made that there are weak intramolecular interactions between the boron atom and the nitrene nitrogen atom of the azido group.     

Removal of Carcinogenic Polycyclic Arenes from Aromatic Softener Oils by Extraction with Dimethyl Sulfoxide and N-Pyrrolidone–Ethylene Glycol Mixed Extractant

Russian Journal of Applied Chemistry - Comparative experimental data on the four-step countercurrent extraction treatment of a mixture of naphthene vacuum gas oil and residual extract with dimethyl...     

Mechanism of the controlled radical polymerization of styrene and methyl methacrylate in the presence of dicyclopentadienyltitanium dichloride

The mechanism of the controlled radical polymerization of styrene and methyl methacrylate in the presence of dicyclopentadienyltitanium dichloride (Cp₂TiCl₂) was studied using quantum chemical calculations and electron spin resonance spectroscopy. It was established that the reduction of Cp₂TiCl₂ to Cp₂TiCl during the macromolecule synthesis occurs through the living polymerization mechanism, which adjusts the growth of a polymeric chain. The geometrical structures of the molecular complexes between a growing macroradical and Cp₂TiCl₂ and transition states of radical inhibition steps were optimized and the thermodynamic and kinetic parameters of the elementary reactions were estimated for several feasible directions of the process. On this basis, the observed kinetic features of vinylic monomer polymerization with participation of organic compounds of titanium are discussed. Copyright © 2004 John Wiley & Sons, Ltd.