A kinetic approach to homogeneous Ziegler type polymerization. Steady state

In this paper we present a kinetic approach to the analysis of steady-state homogeneous Ziegler-Natta polymerization activity data. The influence of the number of monomeric species that are coordinated to the active site on the apparent rate law is discussed and the equations are fitted to the experimental results.     

Alkylation of β-diketones through their co(II), co(III) and zn(II) complexes. 1-Bromoadamantane as alkylating agent.

α-(1-adamantyl)-β-diketones are now accessible by the alkylation of Co(II) complexes of β-diketones with 1-bromoadamantane. The intermediacy of adamantyl cation is proposed. Co(II), Co(III) and Zn(II) complexes of pentane-2,4-dione react with alkyl halides precursors of stabilized carbenium ions, to give 3-alkylpentane-2,4-diones.     

On the wigner-kirkwood coordinate probability distribution of an asymmetric anharmonic oscillator; an addendum

In a recent publication we calculated the Wigner—Kirkwood coordinate distribution function for a symmetric single- or double-well anharmonic oscillator. By a simple transformation, the results are generalized for an asymmetric anharmonic oscillator.     

The propensity rules re-examined: Evidence for a long-lived complex in alkali diatomic-rare-gas collisions

When ΔJ =±1 collision-induced transitions in Π states of excited alkali diatomics are examined over a wide range of pressures several curious phenomena are observed. With the heavier rare gases we find that the ± propensities reverse as pressure increases, and the circular polarisation of the parent line first decreases, with increasing pressure and then begins to rise, the change-over occurring at roughly the same pressure as the reversal ΔJ =±1 collision propensities. A recently proposed theoretical model involving the formation of a long-lived atom—diatomic collision complex or Feschbach resonance is invoked to explain these unusual experimental results.     

Partial synthesis of evonoloside

Conclusions The synthesis of evonoloside has been effected from cannogenol and L-rhamnose with a yield of 35%. It has been shown that when a primary alcohol group (at C₁₉) and a secondary axial hydroxy group (at C₃) are present in the aglycone, to introduce the sugar component at C₃ it is desirable first to protect the primary OH group by the partial acetylation of the aglycone.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 1, pp. 20–22, 1969     

LONG-LIVED AFTERGLOW OF PHOTOSYNTHETIC PIGMENTS IN SOLUTION: PHOTOCHEMILUMINESCENCE

Abstract —Our recent research on photochemiluminescence (PCL) of pigments in solutions is reviewed. PCL was observed in the course of photooxidation by oxygen of chlorophyll a , bacteriochlorophyll, protochlorophyll, their analogs, synthetic dyes and aromatic hydrocarbons. The PCL of chlorophyll was studied in detail. It depends on oxygen concentration, intensity of exciting light, pH, nature of pigments, solvents etc. The thermochemiluminescence was observed after illumination of liquid and solid pigment solutions at low temperature (down to - 170C). The excitation spectra of PCL coincide with the pigment absorption spectra. The PCL emission spectra in most cases differ from those of pigment fluorescence. Electron acceptors, electron donors, radical inhibitors and β-carotene quench PCL. The quenching efficiency of electron acceptors is similar to their action on the chlorophyll triplet state. The quenching effect of radical inhibitors and β-carotene correlates with their activity in reaction with singlet oxygen. The effect of quenchers on the chlorophyll fluorescence, photobleaching and pigment sensitized oxygenation was studied. Analysis of experimental data allowed the assumption that chemiluminescence accompanies the decomposition of labile pigment peroxides. The accumulation of peroxides is probably due to the reaction in the complex of pigment and singlet oxygen, formed as a result of energy transfer from photoexcited (triplet) pigment molecules to oxygen. The terminal chemiluminescence emission proceeds from the singlet excited states of molecules of pigments and products of their oxidation.     

N1-Substitution in 2-methyl-4(5)nitroimidazole. III. New syntheses of 1-(2′-(ethylsulfonyl)ethyl)-2-methyl-5-nitroimidazole

Some new syntheses of 1-[2′-(ethylsulfonyl)ethyl]-2-methyl-5-nitroimidazole (IV), a new antitrichomonal agent are described. The most successful method proved to be alkylation of sodium ethanesulfinate (XXI) with 1-(2′-haloethyl)-2-methyl-5-nitroimidazoles (1a,b) in dimethylformamide.     

Photochemical chlorination of 2-trichloromethyl-1,3-dioxolane

The photochemical chlorination of 2-trichloromethyl-1,3-dioxolane proceeds only at the carbon atoms in the 4 and 5 positions. The structures of the resulting 2-trichloromethyl-4-chloro-and 2-trichloromethyl-4,5-dichloro-1,3-dioxolanes were proved by means of the IR spectra and chemical transformations.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1611–1613, December, 1973.     

Trialkyl-n-(2-vinyloxyethyl)ammonium salts — New systems akin to acetylcholine

Conclusions Vinyloxyethyltrialkylammonium salts possessing strong hypertensive activity were prepared by reacting 2-(dialkylamino)ethyl vinyl ethers with alkyl iodides and 2-halogenoethyl vinyl ethers with tertiary amines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1178–1180, May, 1969.     

The temperature dependence of the d-electron dipole strengths of cobalt(II) tetrahalides

The dipole strengths of the ⁴A₂ → ⁴T₁(F), ⁴T₁(P), d-electron transitions of the cobalt(II) tetrahalides are found to decrease with an increase in temperature, in agreement with a dynamic ligand-polarisation model for the absorption mechanism. The reduction in dipole strength is accounted for by a decrease in the coulombic coupling between the quadrupole moment of the d-electron transition of the metal ion and the transient electric dipole moment induced in the ligands, due to the anharmonic increase in the mean bond length and the progressively larger mean-square amplitudes of the bending modes of the complex ion in its ground electronic state as the temperature is raised.