Application of the Prigogine-Flory-Patterson theory part III. Mixtures of a bicyclic compound,benzene, cyclohexane,n-hexane with a cycloalkane,cyclohexene, a cycloalkadiene and benzene

The Prigogine-Flory-Patterson theory of liquid mixtures has been qpplied to the H _m ^E and V _m ^E for binary mixtures of a bicyclic compound, benzene, cyclohexane and n-hexane with a cycloalkane, cyclohexene, a cycloalkadiene and benzene. Furthermore the Prigogine-Flory theory has been used to predict activity coefficients at infinite dilution from the experimentally determined H _m ^E at 25°C for the mixtures cyclohexane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene and benzene with a bicyclic compound. The predictions are compared to experimental results.     

Catalytic Dehydrogenation of Ethylbenzene in Helium and Reductive Dealkylation in Hydrogen on Nb, Mo, Ta, W, and Re Halide Clusters

Halide clusters of [(Nb₆Cl₁₂)Cl₂(H₂O)₄]4H₂O and (H₃O)₂[(M₆Cl₈)Cl₆] 6H₂O (M=Mo, W), which have an octahedral metal framework, and Re₃Cl₉, which has a triangular metal framework, developed catalytic activity for the dehydrogenation of ethylbenzene selectively to yield styrene when the halide clusters were treated in a stream of helium at 450°C. In the case of the Mo cluster, this catalytic activity appeared at 300°C. The activity increased with increasing temperature. Above 400°C, the catalytic activity decreased with time, and the selectivity for benzene increased noticeably. The reduction in the activity was caused by the formation of coke attributable to ethylene produced as a by-product. When the Nb and Ta clusters of the same structure were treated in a stream of hydrogen in the same way, no catalytic reaction proceeded. However, the Mo and W clusters in a stream of hydrogen catalyzed reductive dealkylation of ethylbenzene selectively yielding toluene and benzene. In the case of the Mo cluster, the catalytic activity appeared at 400°C, and increased with increasing temperature. The activity did not decrease with time even at high temperatures. The Re cluster, which was reduced to the metal by the treatment in hydrogen, catalyzed ring-opening degradation to yield gaseous hydrocarbons.     

The thermodynamics of mixing C6 and C7 compounds with a bicyclic compound at infinite dilution

The activity coefficients at infinite dilution have been measured at 25°C for cyclohexane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, benzene, n-hexane, 1-hexene, 1-hexyne, n-heptane, 1-heptene and 1-heptyne in decahydronaphthalene, bicyclohexyl, 1,2,3,4-tetrahydronaphthalene and cyclohexylbenzene. These results, together with previously determined H _m ^E and V _m ^E have been used to calculate the partial molar excess thermodynamic properties of mixing at infinite dilution.     

Homogeneous Catalytic Oxidation of Cyclohexene by Nitro Complexes of Copper(II)

This work describes the preliminary study of the homogeneous oxidation reaction of cyclohexene by nitro complexes of copper(II), Cu(CH₃CN)₂(NO₂)Cl (1) and Cu(CH₃CN)₂(NO₂)₂ (2) in acetonitrile, under oxygen pressure (20 atm) at 70 and 100°C. The results show the formation of 2-cyclohexen-1-one and 1,2-epoxyhexane-3-one as main reaction products. Also, it was observed that the oxidation reaction at 100°C with complexes 1 and 2 becomes more selective to the formation of 2-cyclohexene-1-one although the activity of both catalyst decreases.     

1,3-Dipolar cycloaddition of diazomethane and diazocyclopropane to 2-fluoro-3-methylbutadiene and thermal transformations of fluorine-containing vinylpyrazolines and vinylcyclopropanes

Reactions of 2-fluoro-3-methylbuta-1,3-diene with diazomethane in ether at 15 °C and with diazocyclopropane generated in situ by decomposition of N-cyclopropyl-N-nitrosourea in the presence of K₂CO₃ in CH₂Cl₂ at –10 °C selectively involve the double bond at the methyl group to give 3-(1-fluorovinyl)-3-methylpyrazolines. Thermal dediazotization of the latter at 250 °C yields 1-(1-fluorovinyl)-1-methylcyclopropane and -spiropentane 5, which are capable of isomerizing, under more severe conditions (400—600 °C), into 1-fluoro-2-methylcyclopent-1-ene and 5-fluoro-4-methylspiro[2.4]hept-4-ene (7), respectively. Spiropentane derivative 5 partially isomerizes into 1-fluoro-2-methyl-3-methylidenecyclohex-1-ene. In a similar way, thermolysis of 6-(2,3,3-trifluorocyclobut-1-enyl)-4,5-diazaspiro[2.4]hept-4-ene at 400 °C gives a mixture of 1-(spiropentyl)-2,3,3-trifluorocyclobut-1-ene and 2,3,3-trifluoro-1-(2-methylidenecyclobutyl)cyclobut-1-ene. Thermolysis of 1-cyclopropyl-2,3,3-trifluorocyclobut-1-ene at 550—620 °C affords a mixture of 1-(trifluorovinyl)cyclopentene and 2,3-difluorotoluene.     

Transformations of cyclohexa-1,4-diene under the action of biphenyl—alkali metal systems in THF. Synergistic acceleration by mixtures of lithium and sodium

In the interaction of cyclohexa-1,4-diene (1,4-CHD) with a mixture of biphenyl and metallic lithium or sodium in THF at 20 °C, three processes occur, viz., disproportionation of 1,4-CHD to form benzene and cyclohexene, dehydrogenation of 1,4-CHD to form benzene and molecular hydrogen, and dehydrogenation of 1,4-CHD to form benzene and lithium or sodium hydride. In the case of lithium on the use of an equimolar amount of biphenyl, the isomerization of 1,4-CHD to cyclohexa-1,3-diene is also observed. When the molar ratio Li(Na): Ph₂ increases from 1 : 1 to 2 : 1, i.e., when the reaction is carried out in the presence of an alkali metal solid phase, the overall conversion of 1,4-CHD into benzene and cyclohexene increases. The use of mixtures of lithium and sodium leads to acceleration of the processes of the formation of benzene and cyclohexene. The possible mechanism of the synergistic effect found is discussed.     

Stereochemistry of products of aldol condensation of 2-(3-oxo-1,3-diphenylpropyl)cyclohexanone with aromatic aldehydes

The aldol condensation of various aromatic aldehydes with 2-(3-oxo-1,3-diphenylpropyl)cyclohexanone in CH₂Cl₂ in the presence of TiCl₄-Et₃N at 0°C afforded perhydrochromens with two equatorial and one axial substituents whereas the aldol reaction under base catalysis gave perhydrochromens with equatorial substituents.     

Catalytic Hydration of Alkynes over Brønsted Acid Sites Developed on Halide Clusters

When a molecular tungsten halide cluster on silica gel, (H₃O)₂[(W₆Cl₈)Cl₆] · 6H₂O/SiO₂, was treated in a nitrogen stream at temperatures above 250 °C, Brønsted acidity appeared as the result of formation of a hydroxo ligand. The cluster catalyzed hydration of 1-hexyne to yield 2-hexanone. The catalytic activity increased with increasing temperature, the selectivity for 2-hexanone being 70% in the temperature range 250–400 °C. 1-Heptyne, 1-octyne, 1-nonyne, and phenylacetylene were also preferentially hydrated to produce the corresponding ketones. 2-Hexyne provided 2- and 3-hexanones in equal amounts, as happens with Brønsted acid catalysts. Halide clusters of niobium, molybdenum, and tantalum having the same octahedral metal framework were also active catalysts for the reaction.     

Three-component synthesis of 5:6 and 6:6 fused pyrimidines using KF-alumina as a catalyst

A series of fused pyrimidine derivatives were synthesized by the three-component reaction of an aryl aldehyde, urea, or guanidine in ethyl alcohol/dioxane in presence of 1-methyl-1H-pyrrol-2(3H)-one 1, 1-methylpiperidin-2-one 2, 1-methylindolin-2-one 3, or 1,3-dimethyl-dihydropyrimidine-2,4-dione 9 at 80 °C catalyzed by KF-Al₂O₃. For example, when 1-methyl-1H-pyrrol-2(3H)-one 1, arylaldehyde 4, and urea 5 were treated with KF-Al₂O₃ in ethyl alcohol at 80 °C for 3-5 h, we obtained pyrrolo[2,3-d]pyrimidine derivatives in good yield.     

Reactivity of allylic hydrogen in cyclohexadiene towards OH radicals

The yield of benzene in the reaction of 1,4- and 1,3-cyclohexadiene with OH radicals in the presence of oxygen was determined using H₂O₂ and CH₃ONO as OH radical sources. Both in the H₂O₂ and the CH₃ONO systems, the yield of benzene from 1,4-cyclohexadiene was 15.3% and the yield from 1,3-cyclohexadiene was 8.9%. On the basis of the obtained yields, the rate constant for allylic hydrogen abstraction per C? H in cyclohexadiene was determined to be 3.8 × 10^?12 cm³ molecule^?1 s^?1. The branching ratio of the hydrogen abstraction to overall reaction for 1-butene and 1-pentene was estimated to be (25–14)% by applying the obtained rate constants. The result was in good agreement with the branching ratio determined directly by use of the discharge flow photoionization mass spectrometer by Biermann, Harris, and Pitts [4].     

Catalytic dehydrogenation of cyclohexene over MoO<Subscript>3</Subscript>/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts

A series of MoO₃/γ-Al₂O₃ catalysts with different Mo surface densities (Mo atoms/nm²) has been prepared by incipient wetness impregnation method. Structural characteristics of the prepared catalysts were investigated by atomic absorption spectroscopy, X-ray diffraction, Fourier Transform Infrared spectroscopy, N₂ adsorption at −196 °C, and temperature-programmed reduction (TPR). The catalytic activities of the prepared catalysts were tested by cyclohexene conversion between 200 and 400 °C. XRD results indicated that molybdenum oxide species were dispersed as a monolayer on the support up to 4.04 Mo atoms/nm², and the formation of crystalline MoO₃ was observed above this loading. FTIR and TPR results showed that molybdenum oxide species were present predominantly in tetrahedral form at lower loading, and polymeric octahedral forms were dominant at higher loading. Cyclohexene conversion reaction proceeded mainly through the simple dehydrogenation pathway in the studied temperature range 200–400 °C and was found to be highly dependent on MoO₃ dispersion.     

Homogeneous electro-mediated reduction of unsaturated compounds using Ni and Fe as mediators in DMF

The homogeneous electro-mediated reduction (HEMR) of several organic compounds (cyclohexene, cyclohexanone, acetophenone, benzaldehyde, styrene, linalool, 1,3-cyclohexadiene, citral, trans-4-phenyl-3-buten-2-one, and piperine) was carried out using Fe²⁺, Ni²⁺, and [Ni^II(bpy)]Br₂ (bpy=2,2′-bipyridine) as electron mediators. An electrochemical system composed of sacrificial anode (Fe, Ni or Zn), nickel cathode, NaI (0.2 M) as supporting electrolyte in DMF and an undivided cell, was used. A constant current ≤100 mA was applied with a maximum cell potential of 2.0 V. Non-conjugated olefins are not reactive, but ketones may be easily reduced to the respective alcohol. In the case of conjugated olefins and ketones, [Ni^II(bpy)]Br₂ or Ni²⁺ mediator presented good reactivity and selectivity in most cases. Fe²⁺ more efficiently mediates the reduction of carbonyl containing systems. Preliminary electroanalytical studies indicate the complexation of the organic substrate by Fe²⁺ and Ni²⁺ ions and [Ni^II(bpy)]Br₂ complex.     

The W2Cl4(NHCMe3)2(PR 3)2 molecules (R 3=Me3, Et3, Pr n 3, Me2Ph) I. Their isomeric forms,interconversion proeesses,crystalline forms,and detailed molecular structures

A thorough study of compounds with the formula W₂Cl₄(NHCMe₃)2(PR₃)₂, withR ₃=Me₃, Et₃, Prg ⁿ ₃ Me₂,Ph, is reported. In addition to the previously reported crystalline compounds, namely Ia,trans-W₂Cl₄(NHCMe₃)₂(PMe₃)₂ in space group Pmmn;3a,trans-W₂Cl₄(NHCM₃)₂(PEt₃)₂ in space group P2₁/^a (or P2₁/^c); and4,cis-W₂Cl₄(NHCMe₃)₂(PMe₂Ph)₂ in Pna2₁, we have obtained and structurally characterized the following new substances,1b,trans-W₂Cl₄,(NHCMe₃)₂(PMe₂)₂, space group P2₁/^c,a= 12.233 (4) Å,b= 12.872 (4) Å,c=17.095 (5) Å,=93.52 (2)°,Z=4,V=2687 (1) ų 2,cis-W₂Cl₄(NHCMe₃)₂(PMe₃)₂, P2₁/^c,a=9.673 (4) Å,b=17.249 (4) Å,c=16.244 (5) Å,=99.63 (3),Z = 4 ,V=2669 (1) Å.3b,trans-W₂Cl₄(NHCMe₃)₂(PEt₃)₂, Pl,a=16.850 (3) Å,b=17.797 (3) Å,c= 11.459 (2)Å,= 101.02 (1),= 103.13°, y=84.23 (1)°,Z=4,V= 3279 (1) Å5,trans-W₂Cl₄(NHCM₃)₂(PMe₂Ph)₂, Fdd2,a=39.563 (8) Å at 20°C; 39.325 (10) Å at -6O°C,b = 57.543 (17) Å at 20°C; 57.186 (16) Å at -60°C,c= 8.810 (1) Å at 20°C; 8.770 (1) Å at - 60°C ,Z=24,V=20057 (7) ų (20°C), 19723 (8) ų ( - 60°C) .6,trans-W₂Cl₄(NHCMe_{3 2}(PPrⁿ ₃)₂, Pl,a= 17.287 (2) Å (20°C); 17.077 (5) Å (-60°C),b= 19.119 (2) Å (20°C); 18.952 (6) Å (-60°C),c= 12.713 (1) Å (20°C); 12.668 (4) Å (-60°C),Z=4,V= 3980 (1) ų (20°C), 3898 (2) ,ų ( - 60°C). In addition, the structure of3a was re-determined and refined so that the disorder ratio was a refined parameter, leading to a value of 0.520:0.480 instead of being arbitrarily fixed at 0.50:0.50. In all of the structures the molecules are held in eclipsed (but very distorted) rotational conformations and the W-W distances are all within the range of 2.305-2.330 Å. As will be shown in a later paper, for all phosphines, thecis andtrans isomers are of similar stability and an equilibrium mixture exists in solution. It is also shown that1a and3a do not contain unexpectedly short W-N bonds as previously reported.     

Synthesis, characterization and catalytic oxidation of cyclohexene with molecular oxygen over host (zeolite-Y)/guest (nickel(II) complexes of R2[12]1,3-dieneN2O2 and R2[13]1,4-dieneN2O2; R = H, Me, Ph) nanocatalyst (HGN)

12- and 13-Membered diaza dioxa Schiff-base nickel(II) complexes were successfully prepared in a nanoscale microreactor by the template condensation of (1,8-diamino-3,6-dioxaoctane)nickel(II) complex with bifunctional diketones within the nanodimensional pores of zeolite Y. The host–guest nanocatalyst (HGN); ([Ni((R₂[12]1,3-dieneN₂O₂)]²⁺-NaY, [Ni(R₂[13]1,4-dieneN₂O₂)]²⁺-NaY; R = H, Me and Ph) is catalytically very efficient as compared to other neat complexes for oxidation of cyclohexene with molecular oxygen as oxidant in the absence of solvent at 70 °C, affording 2-cyclohexene-1-ol and 2-cyclohexene-1-one.     

Ruthenium catalysts of liquid-phase hydrocracking ofn-alkanes

Catalysts of liquid-phase hydrocracking ofn-alkanes with higher activity than Ru-black were obtained by decomposition of Ru₃(CO)₁₂ and Ru₃(CO)₁₂ +i-Bu₂AlH in alkanes at 180–200°C and 5 MPa H₂ and (benzene)(1,3-cyclohexadiene)ruthenium at 20°C and 0.1 MPa H₂. The system based on Ru₃(CO)₁₂ +i-Bu₂AlH is x-ray amorphous, and the remainder have a 30–60 Å particle size.A. N. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1211–1213, May, 1992.     

Optimization of catalytic, surface and magnetic properties of nanocrystalline manganese ferrite

Single-domain manganese ferrite nanoparticles have been synthesized with narrow particle size distribution using the combustion technique. Influence of fuel ratios on the as-prepared powders were characterized by XRD, SEM, VSM, N₂ adsorption at −196 °C and conversion of cyclohexene at 200–400 °C. Ratios of fuel to cations were maintained variously at 0.0, 0.67, 1.33 and 2.67.The fuel to cations ratio of 2.67 gives better yield in the formation of nanocrystalline Mn ferrite and single-domain particles with a narrow range of size distribution. Maximum magnetization and coercivity values of the investigated ferrite are also greater for the ratio of 2.67. These values measured at room temperature are found to be 68.58 emu/g and 62.57 Oe, respectively. The BET surface area of the investigated solids was found to decrease by increasing the ratio between fuel and cations due to increasing the flame temperature. However, this treatment resulted in a significant increase in catalytic activity of the as-synthesized solids. All solids investigated behaved as dehydrogenation catalysts. The change in fuel/cations ratios did not alter the mechanism of dehydrogenation of cyclohexene, but increased the concentration of active sites involved in the catalyzed reaction.     

Synthesis, characterization and catalytic oxidation of tetrahydrofuran with 16-membered pentaazabis(macrocyclic) copper(II) complexes; {[Cu([16]aneN5)]2R}4+ (R = aromatic nitrogen–nitrogen linkers)

New square-planar bis(macrocyclic)dicopper(II) complexes containing phenylene bridges between 16-membered pentaaza macrocyclic subunits have been synthesized via in-situ one pot template condensation reaction (IOPTCR) of aromatic nitrogen-nitrogen linker (R = 1,4-phenylenediamine; benzidine; 4,4′-diaminodiphenylmethane; 4,4′-diaminodiphenylether; 4,4′-diaminodiphenylsulfone), formaldehyde, bis(1,3-diaminopropane)copper(II) perchlorate and 1,3-dibromopropane in a 1:4:2:2 molar ratio results in the formation of new series of binuclear copper(II) complexes; 1-phenyl- (1); 1,1′-phenyl- (2); 1,1′-diphenylmethan- (3); 1,1′-diphenylether- (4); 1,1′-diphenylsulfone- (5) bis(1,3,7,11,15-pentaazacyclohexadecane)copper(II)), {[Cu([16]aneN₅)]₂R}(ClO₄)₄″. The formation of the macrocyclic framework and the mode of bonding of the complexes have been confirmed by data obtained from elemental analyses, UV-visible, FT-IR, ¹H-NMR, electronic spectral studies, conductivity and magnetic susceptibility measurements. These bis(macrocyclic) complexes catalyzed efficiently the selective oxidation of tetrahydrofuran into tetrahydrofuran-2-one and a small amount of tetrahydrofuran-2-ol and 4-hydroxybutyraldehyde using dil. H₂O₂ as the oxidant.     

Asymmetric epoxidation of cis-1-propenylphosphonic acid (CPPA) catalyzed by chiral tungsten(VI) and molybdenum(VI) complexes

In the presence of 5.0 mol% chiral tungsten(VI) and molybdenum(VI) complexes, the catalytic asymmetric epoxidation of cis-1-propenylphosphonic acid (CPPA) with 30% aqueous H₂O₂ affording (1R,2S)-(−)-(1, 2)-epoxypropyl phosphonic acid (fosfomycin) was first described. The enantioselectivities of the tungsten and molybdenum catalysts depend strongly on the ligands, reaction temperature and solvent. In CH₂Cl₂ at 0 °C for 72 h, complex MoO₂[(+)-campy]₂ catalyzed the asymmetric epoxidation in a 100% conversion of CPPA with the highest 80% ee. The mechanism of the present epoxidation could be described as direct oxygen transfer occurred on the interface of the biphasic H₂O-nonprotic system.     

Activity and selectivity of manganese oxides in alcohols Conversion as influenced by gamma-irradiation

Manganese oxide samples obtained from thermal decomposition of manganese carbonate at 400 and 600 °C were subjected to different doses of g-irradiation within the range 0.2 to 1.6 MGy. The surface and catalytic properties of the above samples were studied using nitrogen adsorption isotherms measured at -196 °C and catalytic conversion of ethanol and isopropanol at 300-400 °C using micropulse technique. The results obtained revealed that manganese oxides obtained at 400 °C consisted of a mixture of Mn₂O₃ and MnO₂ while the samples calcined at 600 °C composed entirely of Mn₂O₃. Gamma-irradiation resulted in a decrease in the particle size of manganese oxide phases with subsequent increase in their specific surface areas. Gamma-irradiation with 0.2 and 0.8 MGy effected a measurable progressive decrease in the catalytic activity in dehydration and dehydrogenation of both alcohols. However, the treated catalyst retained their initial activity upon exposure to a dose of 1.6 MGy. Also, g-irradiation increased the selectivities of the investigated solids towards dehydrogenation of both alcohols. The catalyst samples precalcined at 600 °C exhibited higher catalytic activities than those precalcined at 400 °C.     

Isomerization in the partial ozonolysis of 1,4-cyclohexadiene

Conclusions The methyl ester of 6-oxo-4E-hexenoic acid is formed in the partial ozonolysis of 1,4-cyclohexadiene in MeOH-CH₂Cl₂ in the presence of NaHCO₃ at –70°C and the subsequent action of acetic anhydride and Et₃N.The authors thank L. M. Khalilov for assistance in interpreting the¹³C NMR spectrum.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1156–1157, May, 1989.