The Reactivity of Addends in the 1,3-Dipolar Cycloaddition Reaction

The influence of donor-acceptor interactions and localisation energies on the reactivity of addends in the 1,3-dipolar cycloaddition reaction is examined. It is shown that the interactions between the symmetric frontier orbitals and between the antisymmetric frontier orbitals are qualitatively different in (4π+2π)-cycloaddition reactions. The effects arising as a result of the interaction of the symmetric frontier orbitals lead to an alteration of the position of the transition state on the potential energy surface for the reaction and increase the sensitivity of the 1,3-dipolar cycloaddition reactions to localisation effects. The bibliography includes 113 references. © 1984 The British Library

Influence of paramagnetic admixtures on nuclear magnetic relaxation of tissue water protons

Nuclear spin echo has been used to investigate the possible influence of paramagnetic impurities on spin-lattice relaxation of tissue water protons in aloe leaves. A simple way of solving the problem of the influence of paramagnetic inclusions on the nuclear magnetic relaxation times of water protons in plant tissues is described. It is concluded that in plant tissue one may ignore the influence of oxygen and any paramagnetic impurities on the spin-lattice relaxation of water protons. © 1992

Reactions of dichlorocarbene and arenesulfenyl chlorides with 3,4-epoxy-1-butene and vinylethylene carbonate

Reaction of 3,4-epoxy-1-butene with dichlorocarbene is accompanied by deoxygenation and yields a mixture of 1,1-dichloro-2-vinylcyclopropane, 2,2,2',2'-tetrachlorobicyclopropyl, and 2,2-dichlorocyclopropyloxirane. Arenesulfenyl chlorides react with 3,4-epoxy-1-butene to afford both Markownikoff and anti-Markownikoff addition products, whereas vinylethylene carbonate gives rise exclusively to the anti-Markownikoff adducts

Investigation of the effect of paramagnetic impurities on the spin-lattice relaxation of protons of intracellular water

The authors have studied the effect of the paramagnetic ions - Mn2+ and Fe3+ - on the spin-lattice relaxation of the protons of water in plant cells. It has been established that the paramagnetic impurities contained in plant cells in the usual conditions (in natural quantities) have no appreciable influence on the rate of the spin-lattice relaxation of the protons of water. On the basis of investigation of the proton spin-lattice relaxation with a raised content of the paramagnetic ions (Mn2+) in plant cells the possibility of separating the relaxation times T1l and T1s to which correspond different fractions of water in the cells is demonstrated. © 1979

COULOMETRIC DETERMINATION OF THE EXTENT OF QUATERNIZATION OF POLYVINYLPYRIDINES.

The extent of quaternization can be monitored by determining the bromide ion concentration. When samples are dissolved in acetic acid, bromide ion is formed, the concentration of which depends on the degree of quaternization of the polyvinylpyridine. The electrogenerated iodine(I) forms a stable compound IBr with the bromide ion. It was established experimentally that electrophilic substitution by the iodine(I) on the pyridine ring does not occur

Development of the Northern Sea Route on the Route Murmansk-Vladivostok-Shanghai (China)

The paper considers the development of the Northern Sea Route (NSR) in modern Russia and China. The analysis of cargo turnover and the advantages of the NSR is carried out. The importance of the nuclear icebreaker fleet in the development of the NSR is determined and specified. The route is currently considered as transcontinental and it is planned to become part of the “Silk Road”. It belongs to the number of Russian national projects. As an international transit highway, the Northern Sea Route has a huge potential for international cooperation and development of the North and East of Russia. The cluster-modular approach in the organization of NSR is considered. © 2022 The Authors. Published by ELSEVIER B.V

The Reactivity of Addends in the 1,3-Dipolar Cycloaddition Reaction

The influence of donor-acceptor interactions and localisation energies on the reactivity of addends in the 1,3-dipolar cycloaddition reaction is examined. It is shown that the interactions between the symmetric frontier orbitals and between the antisymmetric frontier orbitals are qualitatively different in (4π+2π)-cycloaddition reactions. The effects arising as a result of the interaction of the symmetric frontier orbitals lead to an alteration of the position of the transition state on the potential energy surface for the reaction and increase the sensitivity of the 1,3-dipolar cycloaddition reactions to localisation effects. The bibliography includes 113 references. © 1984 The British Library

The Reactivity of Addends in the 1,3-Dipolar Cycloaddition Reaction

The influence of donor-acceptor interactions and localisation energies on the reactivity of addends in the 1,3-dipolar cycloaddition reaction is examined. It is shown that the interactions between the symmetric frontier orbitals and between the antisymmetric frontier orbitals are qualitatively different in (4π+2π)-cycloaddition reactions. The effects arising as a result of the interaction of the symmetric frontier orbitals lead to an alteration of the position of the transition state on the potential energy surface for the reaction and increase the sensitivity of the 1,3-dipolar cycloaddition reactions to localisation effects. The bibliography includes 113 references. © 1984 The British Library

The Reactivity of Addends in the 1,3-Dipolar Cycloaddition Reaction

The influence of donor-acceptor interactions and localisation energies on the reactivity of addends in the 1,3-dipolar cycloaddition reaction is examined. It is shown that the interactions between the symmetric frontier orbitals and between the antisymmetric frontier orbitals are qualitatively different in (4π+2π)-cycloaddition reactions. The effects arising as a result of the interaction of the symmetric frontier orbitals lead to an alteration of the position of the transition state on the potential energy surface for the reaction and increase the sensitivity of the 1,3-dipolar cycloaddition reactions to localisation effects. The bibliography includes 113 references. © 1984 The British Library

Influence of paramagnetic admixtures on nuclear magnetic relaxation of tissue water protons

Nuclear spin echo has been used to investigate the possible influence of paramagnetic impurities on spin-lattice relaxation of tissue water protons in aloe leaves. A simple way of solving the problem of the influence of paramagnetic inclusions on the nuclear magnetic relaxation times of water protons in plant tissues is described. It is concluded that in plant tissue one may ignore the influence of oxygen and any paramagnetic impurities on the spin-lattice relaxation of water protons. © 1992