Kinetic investigation of propane oxidation on diluted Mo1–V0.3–Te0.23–Nb0.125–Ox mixed-oxide catalysts

Reaction kinetics and proposed mechanism for the oxidation of propane over diluted Mo₁–V_0.3–Te_0.23–Nb_0.125–O _x are described. The kinetic study allowed determination of the orders of propane disappearance, propene formation, CO _x formation, and acids formation. The results show that selective oxidation of propane to propylene over this catalyst follows the Langmuir-Hinshelwood mechanism. Deep oxidation of propane to carbon dioxide is first order with respect to hydrocarbon, and partial order (0.21) with respect to oxygen. The selective oxidation of propane to acrylic acid is half order with respect to hydrocarbon and partial order (0.11) with respect to oxygen, while water does not participate directly in propane transformation. The result also shows that the overall reaction consists of three parallel process channels. One main sequence of consecutive reactions leads to the desired product.     

A FeCl3-promoted highly atropodiastereoselective cascade reaction: synthetic utility of radical cations in indolostilbene construction

The FeCl₃-promoted oxidative cyclization/coupling of acetamidostilbenes possessing 3-methoxy, 4-methoxy and 3,5-methoxy substitutions (21), (22) and (23) is described. Only 3,5-substitution gave rise to novel indolostilbenes, each possessing two stereogenic axes (axially chiral but racemic dimers (39) and (40)). The 4-methoxy substituted acetamidostilbenes, by contrast, yielded the bisindoline dimer (36).     

Origin of the Correlation of the Rate Constant of Substrate Hydroxylation by Nonheme Iron(IV)–oxo Complexes with the Bond‐Dissociation Energy of the C?H Bond of the Substrate

A series of hydrogen‐abstraction barriers of a nonheme iron(IV)–oxo oxidant mimicking the active species of taurine/α‐ketoglutarate dioxygenase (TauD) are rationalized by using a valence‐bond curve‐crossing diagram (see figure). It is shown that the barriers correlate with the strength of the C? H bond. Furthermore, electronic differences explain the differences between nonheme and heme iron(IV)–oxo hydrogen‐abstraction barriers.

     

Zinc Hydrogensulfate as an Efficient Catalyst for Preparation of β-Amido Carbonyl Compounds

A one‐pot and efficient three‐component condensation of benzaldehyde derivatives, enolizable ketones or ketoesters, acetyl chloride, and acetonitrile or benzonitrile under ambient conditions in the presence of zinc hydrogensulfate for the synthesis of β‐amido carbonyl compounds is described. The simple experimental procedure, high to excellent yields of products and preparation of diastereoselective β‐acetamido ketoesters are strong features of the presented method.     

One-pot Synthesis of 1,8-Dioxo-decahydroacridine Derivatives in Aqueous Media

A new and efficient method for the synthesis of 1,8‐dioxo‐9‐aryl‐decahydroacridine derivatives was developed via a one‐pot three component reaction of dimedone, aromatic aldehydes and ammonium acetate in the presence of ammonium chloride, or Zn(OAc)₂·2H₂O or L‐proline separately in water in the short period of time and high yields.     

A Novel Catalytic Method for the Oxidation of Sulfides to Sulfoxides with Silica Sulfuric Acid and Sodium Nitrite in the Presence of KBr and/or NaBr as Catalyst

Highly efficient selective oxidation of sulfides to sulfoxides by NaNO₂ and silica sulfuric acid catalyzed with KBr or NaBr has been reported. This oxidation was carried out in the presence of wet SiO₂ (50% w/w) in acetonitrile at room temperature with good to excellent yields.     

Zinc chloride catalyzed synthesis of 5-substituted 1H-tetrazoles under solvent free condition

Zinc chloride is an efficient and safe catalyst in the[3 + 2]cycloaddition reaction of organic nitriles with sodium azide in solventless condition.The corresponding S-substituted 1H tetrazoles were obtained under mild conditions.This method can overcome disadvantages such as:the use of toxic metals and expensive reagents,drastic reaction conditions,water sensitivity and the presence of dangerous hydrazoic acid.     

V（HSO4）3 catalyzed chemoselectivity acetylation of alcohols and phenols in solution and under solvent-free conditions

A variety of alcohols and phenols are efficiently acetylated with acetic anhydride in the presence of a catalytic amount of V(HSO4)3 in solution and under solvent free conditions.Mild reaction conditions,high yields of the products,easy procedure and selective acetylation of alcohols and phenols in the presence of amines and thiols are the main advantages of this procedure.     

Kinetic studies of the oxidative coupling of methane over the Mn/Na2WO4/SiO2 catalyst

Oxidative coupling of methane is a direct way to obtain C2 hydrocarbon,and Mn-Na-W/SiO2 catalyst is the most promising among all the catalysts.The 2%Mn/5%Na2WO4/SiO2 catalyst was prepared by the incipient wetness impregnation method.A 7-step heterogeneous reaction model of the oxidative coupling of methane to C2 hydrocarbons was conducted by co-feeding methane and oxygen at a total pressure of 1 bar over the catalyst.The kinetic measurements were carried out in a micro-catalytic fixed bed reactor.The kinetic data were obtained at the appropriate range of reaction conditions (4 kPa＜Po2 ＜20 kPa,20 kPa＜PCZH4 ＜80 kPa,800℃＜T＜900℃).The proposed reaction kinetic scheme consists of three primary and four consecutive reaction steps.The conversions of hydrocarbons and carbon oxides were evaluated by applying Langrnuir-Hinshelwood type rate equations.Power-law rate equation was applied only for the water-gas shift reaction.In addition,the effects of operating conditions on the reaction rate were studied.The proposed kinetic model can predict the conversion of methane and oxygen as well as the yield of C2 hydrocarbons and carbon oxides with an average accuracy of ±15%.     

Density and viscosity of 1-butyl-3-methylimidazolium nitrate with ethanol, 1-propanol, or 1-butanol at several temperatures

Densities and viscosities of 1-butyl-3-methylimidazolium nitrate [Bmim][NO₃], and its binaries with alcohol (ethanol, 1-propanol, or 1-butanol) were measured at different temperatures. The densities and viscosities of pure ionic liquid were correlated successfully by empirical equations. The Vogel–Fulcher–Tammann equations can fit the experimental data of viscosities for pure IL. Excess molar volume and viscosity deviations were calculated for the binaries. The excess molar volumes have negative deviations from the ideal solution.