Liquid-phase noncatalytic oxidation of monoterpenoids with nitrous oxide

A series of monoterpenoids differing in the number of double bonds and the pattern of their substitution were tested in the liquid-phase noncatalytic oxidation with nitrous oxide (N₂O). The structure of olefins has a significant effect on the oxidation route. In the case of terpenoids containing 1,1-disubstituted double bond, nor-carbonyl compounds are formed with high selectivity. Dedicated to the memory of Academician N. N. Vorozhtsov on the 100th anniversary of his birth. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1193–1197, June, 2007.     

Non-catalytic liquid phase oxidation of alkenes with nitrous oxide. 1. Oxidation of cyclohexene to cyclohexanone

A very efficient way of alkenes oxidation to carbonyl compounds is discovered. It is based on remarkable ability of nitrous oxide to interact directly with the double C=C bonds of liquid alkene and to transfer its oxygen, without catalyst aid, to unsaturated carbon atom with nearly 100% selectivity. This oxidation method can be applied to a wide range of organic compounds including aliphatic, cyclic, heterocyclic alkenes and their numerous derivatives.     

Non-catalytic liquid phase oxidation of alkenes with nitrous oxide. 2. Oxidation of cyclopentene to cyclopentanone

A very efficient way of cyclopentanone production via selective liquid phase oxidation of cyclopentene with nitrous oxide is reported. When contacting liquid cyclopentene at high temperature, nitrous oxide is able to interact directly with the C=C double bond of the hydrocarbon and transfer its oxygen to unsaturated carbon atom. The reaction occurs without catalyst with nearly 100% selectivity.     

Effect of ZSM-11 crystallinity on its catalytic performance in benzene to phenol oxidation with nitrous oxide

Evolution of ZSM-11 zeolite crystal and pore structure has been studied at 150°C depending on the synthesis time. The amorphous gel was shown to be catalytically inert over the whole induction period, which precedes the crystallization process. The concentration of active sites and the catalytic activity in the oxidation of benzene to phenol is related to the zeolite structure formation and the increasing degree of crystallinity.     

Cyclohexanone preparation via the gas phase carboxidation of cyclohexene by nitrous oxide

Summary Nitrous oxide is known to provide non-catalytic liquid phase oxidation of alkenes to carbonyl compounds (the carboxidation reaction). This paper shows that carboxidation of cyclohexene can be successfully conducted in the gas phase, too. The gas phase carboxidation is a second order reaction proceeding at 325-450°C under 3-16 bar pressure with an activation energy of 26 kcal/mol. The reaction mechanism does not involve free radical steps and leads to cyclohexanone as a main product.     

A synergetic effect in nitrous acid formation by sonolysis of nitric acid in the presence of nitrous oxide

A synergetic effect is found in the sonochemical formation of HNO₂ in HNO₃ solution in the presence of an N₂O–Ar gaseous mixture. The maximum rate of HNO₂ formation is observed at an N₂O : Ar ratio of 15 : 85 (v/v). During the sonolysis of 4 M HNO₃ solutions, the rate of HNO₂ formation increases multifold due to the synergetic effect. The rate of sonochemical hydrazine decomposition in nitrate solutions also increases considerably in the presence of N₂O.     

Decomposition of nitrous oxide on AlFe-PILC catalyst

Summary Two AlFe-PILC catalysts were prepared with different OH/metal ratio and applied in nitrous oxide (N₂O) decomposition reactions. The 100% conversion of N₂O with NH₃into N₂and H₂O was achieved below 500^oC with both applied catalysts. However, the activity of catalysts in direct conversion of N₂O into N₂and O₂did not exceed 40 % below 500^oC. In this reaction the activity of AlFe-PILC catalyst synthesized at higher OH/metal ratio (4) is higher compared to the activity of AlFe-PILC catalyst with OH/metal ratio (2). Free FeO·Fe₂O₃particles were registered in the AlFe-PILC catalyst with higher OH/metal ratio (4).     

Effect of potassium on alumina supported chromium oxide catalysts for methylene chloride oxidation

Alumina supported chromium oxide catalysts added potassium were prepared and tested for methylene chloride oxidation. They were investigated by XRD, BET, XPS, chemisorption. Chromium oxide catalyst added potassium of 1 wt.% has a large beneficial effect on activity. This revised version was published online in August 2006 with corrections to the Cover Date.     

High resolution fourier spectroscopy of nitrous oxide at elevated temperatures

The Air Force Geophysics Laboratory high resolution interferometer has been used to measure the infrared absorption spectrum in the 8-m region of a nitrous oxide sample heated to temperatures up to 800 K. A least-squares-fit was then used to obtain effective molecular constants for 18 rotation-vibration bands. These constants predict the position of spectral lines originating from excited rotational states with an accuracy considerably greater than previously available constants.     

Liquid-phase oxidation of thiols with chlorine dioxide

The products and kinetics of the liquid-phase oxidation of 11 aliphatic and aromatic thiols with chlorine dioxide were studied at –10—+70 °C in organic media. The rate constants and activation parameters of the reaction were determined. The influence of the thiol structure on its reactivity was studied. A strong solvent effect on the reaction rate constant was found, and the reaction mechanism was proposed.     

A novel oxygen-dependent deoximation by nitric oxide

A variety of aldoximes and ketoximes were oxidized to corresponding aldehydes and ketones by nitric oxide in the presence of oxygen.A presumed mechanism was suggested.     

Amberlyst-15催化丁酮氧化制备过氧化甲乙酮

作为一种新型绿色催化剂,离子交换树脂能够代替某些有机反应中的传统催化剂。本文以离子交换树脂Amberlyst-15为催化剂,由30%的双氧水、丁酮和稀释剂邻苯二甲酸二丁酯合成过氧化甲乙酮。在双氧水与丁酮的摩尔比为1.0,离子交换树脂与丁酮的质量比为0.06,反应温度为27℃,反应时间55 min的条件下,过氧化甲乙酮的产率接近86%,活性氧含量为12.9%。Amberlyst-15在循环使用8次后,依然保持良好的稳定性。研究表明:Amberlyst-15用于过氧化甲乙酮的制备具有催化活性高、可重复使用、清洁无腐蚀等优点,为工业环保生产有机过氧化物提供了新途径。     

The use of nitrous oxide for supercritical fluid extraction of pharmaceutical compounds from animal feed

Supercritical fluid extraction (SFE) coupled “off-line” with HPLC analysis has been applied to pharmaceutical analysis: two different matrixes (rodent and dog feed) were spiked with compounds under investigation in pharmacological studies in order to study the supercritical extraction of such matrixes prior to further analysis and quantification of the compounds of interest. The fluid flow-rate in the SFE system was governed by the geometric characteristics (internal diameter and length) of the linear fused silica capillaries. The changes in fluid flow-rate, between experiments, for each new restrictor, required the introduction of the term Total Gaseous Fluid Volume (TGFV), which enabled a series of extraction results to be compared. The comparative behavior of nitrous oxide and carbon dioxide as supercritical extraction fluids was investigated. Results obtained using pure supercritical fluids with high solvating power (density 0.79 g ml^?1) and fluids modified with a polar liquid solvent (methanol and acetonitrile) are discussed.     

Palladium oxide nanoparticles supported on graphene oxide: A convenient heterogeneous catalyst for reduction of various carbonyl compounds using triethylsilane

Palladium oxide nanoparticles supported on graphene oxide ‐ triethylsilane was found to be an effective reductive system for a broad range of reduction processes, including the reduction of various carbonyl compounds such as aromatic aldehydes to their corresponding alcohols or methyl arene compounds, aromatic ketones to their respective alcohols or saturated compounds, aromatic acyl chlorides to their reduced compounds. The desired products were obtained in good to excellent yields under mild conditions. The heterogeneous environmentally friendly catalyst can be easily separated from the reaction mixture through a simple filtration, facilitating purification of the prepared compounds.     

Generation of methylene by the liquid phase oxidation of isobutene with nitrous oxide

The application of nitrous oxide as an alternative oxidant provides new opportunities for selective oxidation of olefins. Here, we studied for the first time the thermal oxidation of isobutene with N₂O in the liquid phase. The study revealed that the oxidation proceeds via 1,3-dipolar cycloaddition of N₂O to the CC bond by two routes forming unstable 4,5-dihydro-[1,2,3]-oxadiazole intermediates. The main route (the contribution of 91%) includes the addition of the N₂O oxygen to the second carbon atom in olefin. In this case, the oxadiazole decomposes with the CC bond cleavage yielding acetone, methylene (:CH₂), and N₂. The methylene then readily reacts with isobutene and benzene (solvent). The minor route involves the addition of the N₂O oxygen to the first carbon atom and the oxadiazole decomposition with a hydrogen shift leading to isobutanal and N₂.The main distinctive feature of the studied reaction is the formation of methylene in high yield.     

Oxidative dehydrogenation of propane by nitrous oxide and/or oxygen over Co beta zeolite

The oxidative dehydrogenation of propane has been studied with nitrous oxide (or mixture of nitrous oxide and oxygen) as oxidant. Nitrous oxide is a more selective but less active oxidant as compared with molecular oxygen. Upon increasing the concentration of N2O in the reaction mixture of propane and oxygen results in a substantial increase of propane conversion, while the selectivity to propene remains constant. The synergistic effect of O₂ and N₂O leads to a threefold higher yield of propene relative to than that of oxygen or nitrous alone. This revised version was published online in June 2006 with corrections to the Cover Date.     

C-H oxidation using graphite oxide

Graphite oxide was found to be an effective oxidant for use in a broad range of reactions, including the oxidation of olefins to their respective diones, methyl benzenes to their respective aldehydes, diarylmethanes to their respective ketones, and various dehydrogenations. The temperatures used in the reactions were typically mild (100-120 °C), and the heterogeneous nature of the oxidant facilitated isolation and purification of the desired products. In most cases, no by-products were observed and the desired products were isolated in good to excellent yields.     

Structures, energetics and reaction mechanisms of nitrous oxide on transition-metal-doped and -undoped single-wall carbon nanotubes

The catalytic activity of carbon nanotubes (CNTs) for the removal of greenhouse gases, like nitrous oxide (N(2)O), can be fine-tuned by metal doping. We modify the inert surfaces of CNTs with Sc, Ti and V transition metals in order to investigate their capability of converting N(2)O to N(2). The stable composite catalysts of Sc-, Ti- and V-doped (5,5)single-walled carbon nanotubes (SWCNTs), along with the unmodified one were investigated by periodic DFT calculations. Without metal doping, the N(2) O decomposition on the bare tube proceeds over a high energy barrier (54.3 kcal mol(-1)) which in the presence of active metals is reduced to 3.6, 8.0 and 10.2 kcal mol(-1) for V-, Ti- and Sc-doped (5,5)SWCNTs, respectively. The superior reactivity is a result of the facilitated electron transfer between the tube and N(2)O caused by the overlap between the d orbitals of the metal and the p orbitals of N(2)O.     

Thermal oxidation of blends of poly(ethylene oxide) and poly(methyl methacrylate)

Thermal oxidation of poly(ethylene oxide) (PEO) and its blends with poly(methyl methacrylate) (PMMA) were studied using oxygen uptake measurements. The rates of oxidation and maximum oxygen uptake contents were reduced as the content of PMMA was increased in the blends. The results were indicative of a stabilizing effect by PMMA on the oxidation of PEO. The oxidation reaction at 140°C was stopped at various stages and PMMA was separated from PEO and its molecular weights were measured by gel permeation chromatography (GPC). The decrease in the number-average molecular weight of PMMA was larger as the content of PEO increased in the blends. The visual appearance of the films suggested that phase separation did not occur after thermal oxidation. The activation energy for the rates of oxidation in the blends was slightly increased compared to pure PEO. © 1992 John Wiley & Sons, Inc.     

Total oxidation of benzene using Cu-Cr mixed oxide as catalyst

Benzene total oxidation on a Cu-Cr supported catalyst was investigated using the work function method. Above 300°C, the majority of the oxygen species on the surface was O²⁻ in the absence or in the presence of hydrocarbon.