Metal complexes in catalytic transformations of olefins. 6. Mechanism of formation and characteristics of the precursors of active centers of ethylene dimerization to butene-1 in the Ti(O-n-Bu)4-AlEt3 system in ethers

Reaction of Ti(O-n-Bu)₄ (TBT) with AlR₃ (R = Me, Et,i-Bu) in solvents such as R₂O, Py, and Et₃N, reduces Ti(IV) to Ti(III), Ti(II), or Ti(I). The organotitanium compounds formed by the reaction of TBT with organoaluminum compounds (OAC) undergo homolytic decomposition at the bond in Ti-C. Isotopic exchange analysis using C₂D₄ suggested the formation of particles containing Ti-CH₂CH₂-Ti, Al-CH₂CH₂-Al, Al-CH₂CH₂-Ti, M=CHCH₃, and MMCHCH₃ (M, M = Al or Ti) fragments. An ESR spectral analysis established that reaction of TBT with TEA in R₂O, Py, and Et₃N environments produced two types of paramagnetic complexes, precursors of active centers of ethylene dimerization. The influence of various factors on the kinetics of accumulation and consumption of these complexes was investigated and their structures are suggested.Deceased.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1516–1525, July, 1992.     

Heterocyclic analogs of xanthone

A comparative investigation of the acid-base properties, the polarographic behavior, and the spectral characteristics of oxochromeno- and oxothiochromenopyrazoles, oxodipyrazolopyrans, and their electronic analogs xanthone and thioxanthone, has been performed. The difference in properties is due to the electron-accepting nature of the condensed pyrazole ring.For communication III, see [8].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 990–992, July, 1973.     

Angular structure of laser radiation in a Markov binary mixture

Laser-radiation transfer in a Markov binary mixture is compared to transfer in an equivalent homogeneous medium. Within the framework of a small-angle approximation a system of equations that describe the angular moments of the second order (angular dispersion) for a laser beam and the equation for laser-beam intensity is obtained. The results of the calculations show a significant effect of the stochastic nature of the medium on the intensity and the angular structure of the laser beam. Deceased Institute of Applied Optics, National Academy of Sciences of Belarus, 11, Belynitskii-Birulya St., Mogilev, 272793. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 36–42, January–February, 1999.     

Optical Transfer Function of a Binary Markovian Mixture

A system of differential equations describing the optical transfer function (OTF) of a binary Markovian mixture is considered in a small-angle approximation. Its analytical solution has been found for the case where the mixture components have different extinction and scattering coefficients but identical scattering indicatrixes. The results of investigation show that the optical transfer function of the binary Markovian mixture depends strongly on the dimensions of nonuniformities and on the difference between the optical parameters of the mixture components, but it always markedly exceeds the optical transfer function of a uniform medium.     

Impact of impurities on the α-LiIO3 crystal growth: Technique for measuring the “dead zone”

Lithium iodate (α-LiIO₃) single crystal is a promising nonlinear optical material, which used for efficient laser radiation conversion in the visible and near-IR regions. A technique for measuring the “dead zone” (ΔТ _dz) of LiIO₃ solutions has been developed; data on the impact of Fe(IO₃)₂, AgIO₃, CsOH, H₃PO₄, and methyl methacrylate on the growth of the (100) face of α-LiIO₃ crystals have been presented; and the dependences of the nucleation and motion of single steps on the degree of supersaturation have been measured. It is shown that the ΔТ _dz value makes it possible to estimate the validity of solutions for growing α-LiIO₃ crystals. The results of measuring the face growth rates and step velocities for KDP and α-LiIO₃ crystals are compared.

     

Kinetics and mechanism of acetylene hydromethylation on organonickel catalysts

Kinetics of methane interaction with acetylene on Ziegler-Natta type organonickel catalysts has been studied. The reaction is first order with respect to methane. The kinetic isotope effect amounts to K_{CH 4}/K_{CD 4}=1.5 and K_{C 2}H₂,CH₄,H₂/K_{C 2}D₂,CD₄,D₂=2.0.

---

-. -. K_{CH 4}/K_{CD 4}, K_{C 2}H₂,CH₄,H₂/K_{C 2}D₂,CD₄,D₂ 1,5; 2,0. .