Copper precipitation from sulfate solutions with calcium carbonates

Mechanism of interaction of copper sulfate with natural calcium carbonates, responsible for low residual copper concentrations in solutions and for the behavior of open and closed systems in storage is considered.     

Dehydrogenation of propane on aluminoplatinum catalysts modified with Re,Zr, Sc,and Sn

The effect of addition of Re, Zr, Sc, and Sn on an aluminoplatinum catalyst in the reaction of dehydrogenation of propane was investigated. It was shown that addition of 0.2–0.5% Zr, Sc, or Re virtually does not alter the catalytic properties of the aluminoplatinum catalyst (APC); addition of 0.2% Sn increases the activity, selectivity, and stability of Pt/Al₂O₃. The amount of coke deposited on the APC after the first 5 min of work decreases by three times in the presence of Sn. The coke is more enriched with hydrogen than the other systems formed on the surface of Pt-Sn/Al₂O₃.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 765–771, April, 1991.     

On the structure and activity of a Pt/C catalyst subjected to repeated deactivation and regeneration cycles

Electron microscopic studies reveal that repeated air/hydrogen regeneration cycles cause irreversible structural changes of a Pt/C catalyst involving sintering and migration of the platinum over the support. This is reflected by a serious decrease of the catalytic activity. With hydrogen treatment only, these effects are less significant.

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, / Pt/C, . . .

     

Metal complexes in the catalytic reactions of olefins. 1. Comparison of the catalytic properties of triphenylphosphine nickel complexes both individually and heterogenized on Al2O3 in the dimerization of ethylene

Conclusions By studying the liquid-phase dimerization of ethylene in the presence of Cat-Et₃Al₂-Cl₃ catalytic systems based on a nickel complex heterogenized on Al₂O₃ and a number of model nickel complexes, a similar activity and selectivity of the process has been established (Cat=NiPPh₃(CO)₂L, where L=PPh₃, CO, Al₂O₃; Ni(PPh₃)₂(CO)₂; Ni(PPh₃)₂(₂-C₂H₄); Ni[P(C₆H₁₁)₃]₂(H)Cl and Ni(PPh₃)(Et)Cl).The results of the investigation agree with the hypothesis that mono- and diolefinic nickel complexes are formed as the active intermediates in the reaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2466–2469, November, 1988.     

Electrochemical iodination of C-methyl derivatives of dodecahydro-7,8-dicarba-nido-undecaborate anion

By electrochemical iodination of potassium 7-methyl-7,8-dicarba-nido-undecaborate and potassium 7,8-dimethyl-7,8-dicarba-nido-undecaborate, their monoiodine derivatives (extracted as tetramethylammonium salts) are synthesized. Their structure is confirmed by NMR and IR spectra and also by elemental analysis data.     

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.     

Synthesis of Schiff bases and benzylamino derivatives containing [1-B<Subscript>10</Subscript>H<Subscript>9</Subscript>NH<Subscript>3</Subscript>]<Superscript>−</Superscript> anion

Reactions of an amino derivative of the closo-decaborate anion [1-B₁₀H₉NH₃]^– with aromatic aldehydes afforded Schiff bases [1-B₁₀H₉NH=CHAr]^– (Ar=Ph, C₆H₄-2-OMe, or C₆H₄-4-NHCOMe). The reduction of the latter with sodium borohydride gave the corresponding benzylamino derivatives [1-B₁₀H₉NH₂CH₂Ar]^–.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2004–2007, September, 2004.