Copper-containing polymethylsilsesquioxane nanocomposites in catalytic olefination reaction

New copper-containing organosilicon hybrid materials were synthesized by the reaction of branched polymethyl- silsesquioxane with copper nanoparticles prepared by the metal-vapor synthesis. Hybrid materials showed a high activity in the catalytic olefination of p-chlorobenzaldehyde hydrazone with polyhaloalkanes such as CBrCl₃, CBr₄ and CF CBr to afford the corresponding halostyrenes in the yields above 80%. The structure and composition of the prepared nanocomposites were studied by X-ray using synchrotron radiation to show that the active sites of the catalysts are mixed copper(I)–copper(II) oxides (Cu–Cu₂O–CuO) in nature.     

Synthesis of bis(halovinyl)benzenes by catalytic olefination

Catalytic olefination of hydrazines of terephthalic and isophthalic aldehydes with polyhaloalkanes afforded the corresponding p- and m-divinylbenzene derivatives bearing halogen atoms and various functional groups at the double bonds. Stereochemical features of the reaction were studied.     

Palladium-catalysed oxidation of alcohols with carbon tetrachloride,formation of 4,4,4-trichloro ketones from allylic alcohols and carbon tetrachlorid

Pd salts catalyse oxidation of alcohols with CCl₄ in the presence of K₂CO₃. Primary alcohols are oxidised to esters, and secondary alcohols to ketones. CCl₄ is converted to CHCl₃. The reaction of allylic alcohols bearing a terminal olefinic bond with CCl₄ or BrCCl₃ in the presence of palladium catalyst at 110° affords 4,4,4-trichloro ketones. At 40°, simple adducts of CCl₄ or BrCCl₃ having a halohydrin structure are obtained, which are converted to the corresponding trichloro ketones by the catalysis of palladium. Various halohydrins are converted to ketones by Pd catalysis.     

Metallocomplex catalyst of the addition reaction of CCl4 to ethylene

The catalyst Fe^IIFe₂ ^IIICl₈ (DMA)₆-iron(2+)diiron(3+)octachlorohexakis(dimethylacetamide), was isolated from the media of the catalytic synthesis of 1,1,1,3-tetrachloropropane (C₃), and characterized by physicochemical methods. A counter synthesis of the catalyst was carried out. The telomerization of ethylene with CCl₄ proceeds with a 98% selectivity with respect to C₃ in its presence, while the conversion of CCl₄, reaches 55–60% after 4 h. A coordination-ionic mechanism of the reaction of CCl₄ with C₂H₄ was proposed, which followed the concept of the donor-accpetor electron-transporting systems (the DAET systems), thus accounting for its high selectivity.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2794–2798. December, 1990.     

Synthesis of Dendritic Phenol Ether Derivatives with a Naphthalene Core

A series of dendritic phenol ether derivatives with a naphthalene core were synthesized by the Williamson reaction as a coupling reaction between 1‐hydroxymethylnaphthalene and polyether‐based dendritic fragments in the presence of phase‐transfer catalyst and alkali. The modified method for chlorination of dendritic benzyl alcohol was also developed using PPh₃ and CCl₄ as reagents and CH₂Cl₂/CCl₄ as solvent.     

Catalytic olefination reaction of carbonyl compounds. A study on stereoselectivity of alkene formation

The mechanism of formation of alkene stereoisomers in the catalytic olefination reaction of carbonyl compounds was studied. 4-Chlorobenzaldehyde hydrazone 1 stereoselectively reacts with a number of F-, Cl-, Br-, and I-containing polyhaloalkanes in the presence of catalytic amounts of CuCl to give -substituted styrenes 2 with the more thermodynamically stable alkene isomer being the major product. A model for the formation of the stereoisomers of alkenes 2 in the olefination reaction is proposed. Stereoselectivity of the reaction is determined by elimination of copper(ii) halides from the lowest-lying conformers of organocopper intermediates II. According to quantum-chemical calculations, the elimination should involve the staggered conformations with antiperiplanar arrangement of C—Hal and C—Cu bonds and proceed by the E2 anti-elimination mechanism. The results of quantum-chemical calculations are in good agreement with the experimental E/Z alkene isomer ratios.     

Plasma-catalytic Reactor for Decomposition of Chlorinated Hydrocarbons

The conversion of trichloromethane in mixtures with air was investigated under normal pressure in a gliding discharge (GD) reactor operated in both a homogeneous gas system and with a solid catalyst. The Pt catalyst supported by a honey-comb cordierite structure was placed in the reactor below the ends of the electrodes. Cl₂ and HCl were the main products of the CHCl₃ conversion. The presence of CCl₄ was also noted. The influence of the electrode length and the distance between the electrodes in the narrowest section on CHCl₃ conversion was examined. The Pt catalyst revealed some activity in the trichloromethane processing. This resulted in an increased overall CHCl₃ conversion with the portion of CHCl₃ converted to CCl₄ smaller than that in the homogeneous system. The effect of temperature on CHCl₃ conversion was found to be significant.     

Studies of phosphazenes. XIX. New polyorganophosphazenes derived from the friedel–crafts reactions of hexa(aryloxy)cyclotriphosphazenes with polyhaloalkanes

The reactions of hexa(aryloxy)cyclotriphosphazenes N₃P₃(OR)₆[R = C₆H₅, C₆H₄CH₃-p] with polyhaloalkanes in the presence of anhydrous aluminium chloride yield new crosslinked phosphazene polymers which are characterized by elemental analysis, IR spectroscopy, and pyrolysis—mass spectrometric measurements. Soluble “prepolymers” are obtained by using stoichiometric quantities of the phosphazene and haloalkane in nitromethane as the solvent. The ¹H and ³¹P NMR data for these “prepolymers” are presented. The thermal stability of the polymers derived from various haloalkanes decreases in the order 1,2-ClCH₂CH₂Cl < CHCl₃ > CH₂Cl₂ > CCl₄. The thermal stability also increases with increasing amounts of the catalyst, reaching a maximum at 1:10 mol ratio of N₃P₃(OPh)₆:AlCl₃. The phosphazene polymers reported here possess much greater thermal stability compared to linear polyorganophosphazenes, [NPR₂]n, as well as the polymers prepared by the Friedel–Crafts reactions of P(O)(OPh)₃ and P(O)(OC₆H₄CH₃-p)₃ with haloalkanes.     

Telomerisation par catalyse redox—VI: Transformation chimique des tulomeres du chlorotrifluoroethylente

Hydrolysis of the chlorotrifluoroethylene telomers (prepared with CCl₄ or CCl₃ Br as telogen) by 20% oleum, led to a range of chlorofluorinated mono and diacids. The conditions of reaction and especially the role of mercuric oxyde used as catalyst are specified. The ester, amides and alcohol derivatives of these acids have also been synthesized.     

Iron and copper catalyzed reaction of benzylamine with carbon tetrachloride: facile formation of 2,4,5- triphenylimidazoline derivatives

Iron and copper salts catalyzed the reaction of benzylamine with CCl₄ to give a mixture of 2,4,5-triphenylimidazole (1), 1-benzyl-2,4,5-triphenylimidazole (2), 2,4,5-triphenylimidazoline (3), and 1-benzyl-2,4,5-triphenylimidazoline (4) in high yields. The imidazoline 4 was obtained as the main product. The imidazole and imidazoline derivatives were also formed by the iron-catalyzed reaction of benzylidenebenzylamine (8) or dibenzylamine (5) with CCl₄. The imidazoline 4 slowly underwent debenzylation and dehydrogenation with the aid of CCl₄ and iron catalyst to give 1 and 2. From these results, a mechanism involving formation of 5 and 8, subsequent oxidative dimerization of 5 and 8 to form 4, and further conversion of 4 to 1, 2, and 3 is proposed.     

Synthesis of substituted quinolines by the reaction of anilines with alcohols and CCl4 in the presence of Fe-containing catalysts

Substituted quinolines were synthesized by the reaction of aniline derivatives with aliphatic alcohols and CCl₄ upon the action of the FeCl₃·6H₂O catalyst.     

Stereoselective synthesis of analogs of natural isoprenoids based on the reaction of alkyl 4-dialkoxyphosphoryl-3-methylbut-2-enoates with aldehydes in ionic liquids and in an imidazolium salt—benzene system

Condensation of alkyl 4-dialkoxyphosphoryl-3-methylbut-2-enoates with a number of aldehydes under the Horner—Emmons reaction conditions in 1-butyl-3-methylimidazolium hexafluorophosphate and tetrafluoroborate and in 1-butyl-3-methylimidazolium bromide—benzene and 1-butyl-2,3-dimethylimidazolium hexafluorophosphate—benzene systems was studied. The E/Z-stereoisomer ratio of the olefination products for the reaction carried out in ionic liquids was 3 : 1, which corresponds to the values attained previously in the KOH—benzene—Bu₄ ⁿNBr (cat.) system. Quantum-chemical calculations were used to determine the averaged radii (r ₀) of the [Bu₄ ⁿN] and substituted imidazolium cations by means of the Gaussian 98 program package. The stereoselectivity of olefination in the KOH—PhH—phase-transfer catalyst system decreases with a decrease in the r ₀ value for the catalyst cation. The possibility of recovery and reuse of ionic liquids is demonstrated.     

Chemically induced dynamic nuclear polarization and the mechanism of the reaction of Et<Subscript>3</Subscript>Al with CCl<Subscript>4</Subscript> in the presence of transition metal complexes

Integral effects of chemically induced ¹H and ¹³C nuclear polarization are reported for the reaction of Et₃Al with CCl₄ catalyzed by Pd(acac)₂, Cu(acac)₂, and Cp₂TiCl₂; for the reaction of (n-C₈H₁₇)₃Al with CCl₄ in the absence of a catalyst and in the presence of Ni(acac)₂; and for the reaction of the cyclic organoaluminum compound 1-ethyl-3-butylaluminacyclopentane with CCl₄ in the presence of Pd(acac)₂. A scheme of the catalytic cycle of this reaction predicting the formation of both radical and nonradical products is derived from the observed chemically induced dynamic nuclear polarization (CIDNP) effects and from data on the products of the reaction between Et₃Al and CCl₄ in the presence of Pd(acac)₂. According to the results of qualitative analysis of the CIDNP effects, the reactions of the trialkylalanes and the cyclic organoaluminum compound with CCl₄ in the presence of various metal complexes proceeded via similar mechanisms.     

Kinetics and mechanism of the pyrolysis of 1-chloro-1,1-difluoroethane in the presence of additives

The thermal dehydrochlorination CF₂ClCH₃→CF₂(DOUBLEBOND)CH₂+HCl has been studied in a static system between 597 and 664 K in the presence of CCl₄, C₂Cl₆, CF₂(DOUBLEBOND)CH₂, HCl, and CF₃CH₃. A kinetic radical and molecular reaction model has been developed. In addition to describing earlier results on the acceleration of the pyrolysis by CCl₄ and the further acceleration by HCl, this model describes quantitatively up to conversions of 20% (i) the dependence of the catalytic effect of CCl₄ at low concentrations, (ii) the stronger catalytic effect of C₂Cl₆, and (iii) the inhibitory effect of added CF₂CH₂ and CF₃CH₃ when CCl₄ is used as a catalyst. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 359–366, 1998     

Ruthenium-Catalysed Cleavage of Alkenes and Alkynes to Carboxylic Acids

Catalysis of alkene and alkyne cleavage to carboxylic acids by ruthenium trichloride in the presence of an excess of periodic acid has been studied in biphasic H₂O - CCl₄-CH₃CN media, and is found to be simple and effective. The active catalyst is shown to be RuO₄.     

PdCl2(MeCN)2-catalyzed carbonylation of diethylamine with carbon dioxide: Selective synthesis of tetraethylurea and diethylformamide

The reaction of diethylamine with carbon dioxide (CO₂) with PdCl₂(MeCN)₂ as a catalyst gives tetraethylurea(1) or diethylformamide(2) selectively under mild reaction conditions by employing the PPh₃/CCl₄/MeCN and the HCOONa/methyl cellosolve systems, respectively.     

Kinetics of tetrachloromethane fluorination by hydrogen fluoride in the presence of antimony pentachloride

Contradictory information concerning the kinetics of tetrachloromethane fluorination by anhydrous hydrogen fluoride in the presence of antimony pentachloride has been explained. The present studies were performed using a stainless steel autoclave. The exchange of the first chlorine atom was carried out in the temperature range of 35-95 °C, with the molar ratio of HF/CCl₄ varied within the range of 1.2-1.7 and at a constant molar ratio of SbCl₅/Cl₂ equal to 1.9. The degree of conversion of CCl₄ to CCl₃F and the reaction rate constant as a function of temperature fit to an Arrhenius straight line. The Arrhenius constants (pre-exponential factor) and the activation energy were determined. Studies concerning the exchange of the second chlorine atom, i.e. the conversion of CCl₃F to CCl₂F₂ have been performed. The results of kinetic investigations were created in the same way. Based on these results it was found that the Arrhenius equation is fulfilled also in the second stage of the fluorination. The same slope of the straight lines confirms that the fluorination stages proceed according to the same mechanism with the same activation energy but with different pre-exponential factors.Several kinetic problems associated with the performance of the reactor can be solved on the basis of the equations derived. However, knowledge of CCl₄ conversion as a function of time, temperature, catalyst concentration and the type of the reaction is required for this purpose. Such calculations enable the selection of the optimal process parameters.     

An Efficient Approach to 2-CF3-Indoles Based on ortho-Nitrobenzaldehydes

The catalytic olefination reaction of 2-nitrobenzaldehydes with CF₃CCl₃ afforded stereoselectively trifluoromethylated ortho-nitrostyrenes in up to 88% yield. The reaction of these alkenes with pyrrolidine permits preparation of α-CF₃-β-(2-nitroaryl) enamines. Subsequent one pot reduction of nitro-group by Fe-AcOH-H₂O system initiated intramolecular cyclization to afford 2-CF₃-indoles. Target products can be prepared in up to 85% yields. Broad synthetic scope of the reaction was shown as well as some followed up transformations of 2- CF₃-indole.     

Reaktion von Lanthanfluorid mit Halogenalkanen

Reactions of Lanthanum Fluoride with Halogenoalkanes Reactions are reported on lanthanum fluoride as a fluorinating reagent and as a catalyst for the fluorination and dismutation of halogenoalkanes. Carbon tetrachloride, monofluorotrichlormethane, and chloroform are partially fluorinated by lanthanum fluoride. In the presence of HF, lanthanum fluoride acts as catalyst the fluorine transfer to CCl₄, CHCl₃ and C₂F₃Cl₃. Monofluorotrichloromethane, difluorodichloromethane, and trifluorotrichloroethane dismutate on lanthanum fluoride. Results on the thermal decomposition of the above-mentioned fluorochloroalkanes are communicated.     

The mechanism of the addition of tetrachloromethane to oct-1-ene catalysed by [Mo2(CO)6(η-Cp)2]

A study of the reaction of CCl₄ with oct-1-ene in the presence of catalytic amounts of [Mo₂(CO)₆(η-Cp)₂] has shown that in the early stages it proceeds by a redox-catalysed mechanism. However, gradual decomposition of the catalyst leads to the intervention of a radical chain pathway.