Physicochemical characterization of boro- and gallo-silicate isomorphs ofβ-zeolite

The crystalline isomorphs of-zeolite containing boron or gallium in the framework positions have been synthesized and the products characterized by comparing them with Al- zeolite. Evidence for the presence of B or Ga in the zeolite lattice framework has been confirmed by spectroscopic (XRD, IR and²⁹Si,²⁷Al and¹¹B MASNMR), DTA/TG, ion exchange, sorption and catalytic activity results. Chemical analysis and NMR confirm the absence of any significant amount of Al in the zeolite (SiO₂/Al₂O₃=2000). The XRD pattern of the as-synthesized B- and Ga- compounds matched well with that of Al- zeolite. Lattice B and Ga leads to a change in the X-rayd values. Framework and bridging hydroxyl stretching IR bands of-zeolite are shifted due to incorporation of gallium and boron into the zeolitic framework. MASNMR spectra of¹¹B and²⁹Si also suggest the presence of tetrahedrally coordinated B(III) or Ga(III) ions in the-zeolite framework. B and Ga-zeolites exhibit significant ion exchange capacity and catalytic activity in them-xylene isomerization reaction. The shifts in the IR bands towards higher frequency in B- and lower frequency in Ga-, the observed ion exchange capacities and catalytic properties, indicate the presence of B³⁺ or Ga³⁺ ions in the framework of-zeolite.     

α-Tosyloxylation of fluorosubstituted β-diketones

The interaction of fluorinated -diketones with [hydroxy(tosyloxy)iodo]benzene leads to -tosyloxy--diketones existing in the form of stable hydrates.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 541–542, March, 1994.     

Photochemical addition of diethyl ether to β,β,β',β'-tetrakis(trifluoromethyl)divinyl ether

The 1:1 adducts of diethyl and ,,','-tetrakis(trifluoromethyl)divinyl ether (1),i.e., 3,5-(ee)-bis[2,2,2-trifluoro-1-(trifluoromethyl)ethyl]-2,6-dimethyl-1,4-dioxane (2) (3 isomers) and 4-ethoxy-1,1,1-trifluoro-2-trifluoromethyl-3-[3,3,3-trifluoro-2(trifluoromethyl)propenyloxy]pentane (3), have been obtained by UV-irradiation of a solution of divinyl ether1 in diethyl ether. The X-ray structural investigation of the all-(e)-isomer of dioxane (2) has been carried out.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 85–88, January, 1994.     

Formation of pyridines fromN-methylpyrimidinium iodide and enaminoesters

The reaction ofN-methylpyrimidinium iodide with enaminoesters yields a mixture of 3-ethoxycarbonyl-2-methylpyridine and 3,5-diethoxycarbonyl-2,6-dimethylpyridine. Mechanisms of the transformations of the pyrimidine ring found are suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1318–1321, July, 1995.     

Kolmogorov exponents for near-incompressible turbulence from perturbative quantum field theory

I derive the Kolmogorov exponents for the energy spectrum of freely-decaying, fully-developed, near-incompressible turbulence, using the methods of perturbative quantum field theory. In contrast to the approach involving Gaussian random forces, the leading-order result is determined uniquely through selfconsistency. At the first order in , I find a unique and nontrivial, IR (infrared) stable fixed-line. I show that the upper critical dimension of this system is 6, and E(k)k^–2 in 3 dimensions and E(k)k^–3 in 2 dimensions along this nontrivial fixed-line (at the one-loop level).     

Analytical relationships between the ionization of 1,3-dicarbonylic ligands and stability of their Cr(III), Ni(II), Co(II) and Cu(II) 1∶1 chelates

It has been demonstrated that the logarithm of the stability constant of some monochelated chromium(III) compounds, with structurally similar 1,3-dicarbonylic species, is linearly related to the negative logarithm of the acid ionization constant of the ligand. Graphical and analytical correlations which could be useful in predicting equilibrium constants of chromium(III)--diketonates, as well as other first-row transition metal derivatives, have been developed. A quantitative evaluation of the complexes stability has been carried out, providing information about the effects of ligand substituents on the equilibrium constants.     

Transport method for determining the association constants of complexes formed between aromatic hydrocarbons andα- andβ-cyclodextrin in water

The association constants of 1 : 1 complexes formed in water between six aromatic hydrocarbons (o-,m-, andp-xylene, naphthalene, anthracene, and pyrene) and- and-cyclodextrin were determined by the transport method. The values are in good agreement with those determined by other methods.     

Oxidative addition of unsaturated acid esters to 1,3-dimethyluracil and pyrimidine nucleosides

When alkyl esters of acrylic and sorbic acids or acrolein diethylacetal are reacted with 1,3-dimethyluracil or 1--D-xylofuranosyluracil in the presence of Pd(OAc) ₂ , oxidative addition takes place at position 5 of the uracil fragment.Institute of Organic Chemistry, Ural Branch, Russian Academy of Sciences, 450054 Ufa. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1616–1618, July, 1992.     

EFFECT OF N,N,N’,N’-TETRAALKYL TEREPHTHALAMIDE ON NON-ISOTHERMAL CRYSTALLIZATION KINETICS OF POLYPROPYLENE

The effect of N,N,N＇,N＇-tetraalkyl terephthalamide （TATA） on the non-isothermal crystallization and melting characteristics ofpolypropylene （PP） was studied. The addition of TATA can lead to the formation ofβ-crystal PP. With the increase in TATA concentration the degree of crystallinity for β-crystal PP increased significantly, and that for a-crystal PP decreased, which indicated that TATA effectively induced the formation of β-crystal PP. WAXD also revealed the existence of β-crystal PP after the introduction of TATA into PP. PP containing TATA crystallized at a temperature range of 5-10℃ higher than that of pure PP, and the half-crystallization time （t1/2） and Avrami exponent （n） of PP at the same cooling rate were decreased by the addition of TATA, indicating that TATA influenced the crystallization rate and crystallization growth mode of PP. The rate constant of crystallization of PP containing TATA （Zc） was larger than that of pure PP, which further indicated that the crystallization of PP was accelerated by the addition of TATA.     

Molecular structure of crepidioside a and isolipidiol fromCrepis multicaulis

Crepidioside A, a guaian-like sesquiterpene lactone, is isolated fromCrepis multicaulis Ldb, and identified. The structure 15-glycoside-2-oxo-5,7,6(H)-guai-1(10),3(4),11(13)-trien-6,12-olide is found from an x-ray structure analysis. 8-Epi-isolipidiol is isolated fromCrepis tectorum L. Its new polymorphic crystal structure is found from an x-ray structure analysis.Institute of Phytochemistry, Ministry of Science and Higher Education, Republic of Kazakhstan, fax (3212) 43 37 73, Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 139–141, March–April, 2000.