Kinetics and products of the catalytic oxidation of acetamidotoluenes with ozone in acetic acid

The kinetics of acetamidotoluene oxidation in glacial acetic acid in the presence of cobalt acetate is reported. At 95°C and atmospheric pressure, acetamidotoluenes are oxidized by molecular oxygen very slowly: oxidation is complete in 10–12 h, and the major reaction products are acetamidobenzoic acids (27–36% yield). The introduction of ozone into the reactive gas increases the reaction rate by one order of magnitude. The main role of ozone is to generate the active form of the catalyst.     

Catalytic ozonation of alkylnaphthalenes in acetic acid

The oxidation of alkylnaphthalenes with ozone in acetic acid in the presence of cobalt(II) acetate is reported. Under the catalytic conditions, the ozonolysis of the aromatic system can be prevented to a considerable extent and the reaction can be directed toward the oxidation of the alkyl group. The kinetics of the main steps of the process is reported, and the mechanism of redox catalysis is presented.     

Kinetics and products of the reactions of ozone with toluene and its derivatives in acetic anhydride

The reactions of ozone with toluene and its derivatives in acetic anhydride were studied. It was found that competing parallel reactions of ozone with the aromatic ring and substituents occurred in the ozone-arene-acetic anhydride system. The ratio between these reaction paths depended on the arene structure and reaction conditions. The selectivity of the oxidation of toluene and its derivatives at the methyl group varied from 0 to 40%. The fraction of aromatic products decreased as the number of methyl groups at the ring was increased. Tri- and tetramethylbenzenes were oxidized only at the aromatic ring. The stability of an aromatic system increased upon the introduction of electron-acceptor substituents into the benzene ring. Aminotoluenes and hydroxytoluenes were oxidized with ozone mainly at the NH₂ and HO groups; however, as in the case of toluene, the aromatic ring and methyl group became the main directions upon their acylation. The oxidation of the methyl group in acetic anhydride in the presence of sulfuric acid was finished at the step of the formation of the acylated derivatives of benzyl alcohols and benzaldehydes, which are resistant to the action of ozone.     

Atmospheric oxidation pathways of acetic acid

One of the most abundant carboxylic acids measured in the atmosphere is acetic acid (CH(3)C(O)OH), present in rural, urban, and remote marine environments in the low-ppb range. Acetic acid concentrations are not well reproduced in global 3-D atmospheric models because of the poor inventory of sources and sinks to model its global distribution. To understand the complete oxidation of acetic acid in the atmosphere initiated by OH radicals, ab initio calculations are performed to describe in detail the energetics of the reaction potential energy surface (PES). The proposed reaction mechanism suggests that the CH(3)C(O)OH + OH reaction takes place via three pathways: the addition of OH to the central carbon, the abstraction of a methyl hydrogen, and the abstraction of an acidic hydrogen. The PES is characterized by prereactive H-complexes, transition states, and more interestingly unique radical-mediated isomerization reactions. From the analysis of the energetics, acetic acid atmospheric oxidation will proceed mainly via the abstraction of the acidic hydrogen, consistent with previous experimental and theoretical studies. The major byproducts from each pathway are identified. Glyoxylic acid is suggested to be a major byproduct of the atmospheric oxidation of acetic acid. The atmospheric fate of glyoxylic acid is discussed.     

Coulometric generation of acetylions by oxidation of mercury in acetic anhydride and in acetic acid/acetic anhydride mixture

Coulometric generation of acetyl (CH₃CO⁺) ions by oxidation of mercury in acetic anhydride and in acetic acid/acetic anhydride (5:95, v/v) is described. Current/potential curves for solvents, titrated bases, indicator and mercury showed that in both these solvents mercury is oxidized at potentials which are much more negative than those for the titrated bases and other components present in the solution. Quinoline, triethanolamine, triethylamine, pyridine and quinolin-8-ol in acetic anhydride, as well as triethylamine, 2,2′-bipyridine, 2,4,6-collidine, pyridine and sodium acetate in acetic acid/acetic anhydride were titrated with acetyl ions generated by the oxidation of mercury. In this way, it was established that the oxidation of mercury to mercury (I) ions proceeds quantitatively with 100% current efficiency.     

以咖啡酸-KBrO3-H2SO4-Mn^2+为体系的化学振荡及其十字相图

本文报道的是一种新的BZ化学振荡反应。该反应是在酸性介质中,在锰离子催化下,咖啡酸被溴酸盐氧化所引起的化学振荡反应。就该体系在间歇反应器和连续流动体系中的振荡行为作了研究,得出了不同浓度、温度及流速下的特征振荡图形,计算出该振荡反应及其诱导期的活化能,并采用改变流速寻找双稳态的方法找出振荡的浓度区间,作出十字相     

Oxidation of 4-aminotoluene with ozone in acetic acid solution

The possibility of preparing 4-aminobenzoic acid by oxidation of 4-aminotoluene with ozone in acetic acid in the presence of cobalt(II) acetate and potassium bromide was examined. The optimal oxidation conditions were found.     

Catalytic aromatization of Hantzsch 1,4-dihydropyridines by ferric perchlorate in acetic acid

Catalytic oxidation of Hantzsch 1,4-dihydropyridines is described using a catalytic amount of ferric perchlorate in acetic acid at room temperature.     

Ethylene oxidation by lithium nitrate in the presence of palladium acetate in acetic acid

Data are reported on variations of the gas phase volume and product accumulation in ethylene oxidation by lithium nitrate in acetic acid solutions, catalyzed by palladium acetate. An assumption is made on the routes of nitrate ion reduction.

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Oxidation of benzyl alcohol and benzaldehyde with ozone in acetic acid

Ozonation of benzyl alcohol and benzaldehyde in acetic acid was studied. A method for ozonation of these compounds is suggested.     

乙烯直接氧化制乙酸催化剂Pd-H3PO4-Cu/Al2O3的研究

以浸渍法制备了一系列不同Pd担载量的Pd-H3PO4-Cu／Al2O3催化剂，采用微型固定床反应器对乙烯直接氧化合成乙酸工艺进行了活性评价．考查了Pd含量、不同助剂的添加、Cu氧化物含量等对催化剂性能的影响并采用TPR，SEM等方法进行了结构表征．实验结果表明：各组分含量为ωpd=3％，ωH3PO4=50％，ωCu=9．5％时，该催化剂具有较理想的活性与选择性．在反应温度为200℃、压力为0．8Mpa、原料气物质的量比为n(C2H4)：n(O2)：n(N2)：n(H2O)=50：6：14：30的条件下，乙烯的转化率与乙酸的选择性分别达3．8％和86．3％。在Pd-H3PO4／Al2O3催化剂中引入Cu的化合物后，不仅提高了催化剂的活性，而且催化剂的稳定性也有显提高．     

Catalytic oxyfunctionalization of saturated hydrocarbons by non-heme oxo-bridged diiron(III) complexes: role of acetic acid on oxidation reaction

Oxo-bridged diiron(III) complexes [Fe₂O(L¹)₂(H₂O)₂](ClO₄)₄ (1) and [Fe₂O(L²)₂(H₂O)₂](ClO₄)₄ (2), where L¹ and L² are tetradentate N-donor N,N′-bis(2-pyridylmethyl)-1,2-cyclohexanediamine and N,N′-bis(2-pyridylmethyl)ethane-1,2-diamine respectively, have been isolated as synthetic models of non-heme iron oxygenases and characterized by physicochemical and spectroscopic methods. Both the complexes have been studied as catalysts for the oxyfunctionalization of saturated hydrocarbons using green hydrogen peroxide (H₂O₂) as oxidant under mild conditions. The selectivity (A/K) and regioselectivity (3°/2°) in oxidative C–H functionalization of alkanes suggests the involvement of metal-based intermediate in the oxygenation reaction. The catalytic efficiency is found to be strongly dependent on the presence of acetic acid. Remarkable increase in conversion and selectivity favoring the formation of alcohols in the oxidation of cyclohexane and cyclooctane and exclusive hydroxylation of adamantane with drastic enhancement of regioselectivity has been achieved by the addition of acetic acid in the presence of H₂O₂.

     

Liquid phase oxidation of allyl alcohol by air oxygen in acetic acid medium

Studies of the oxidation of allyl alcohol by air oxygen in acetic acid medium indicate that one of the intermediates is allyl epoxide transforming in 90% to polyglycerol esters of acetic and formic acids.

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A new process for acetic acid production by direct oxidation of ethylene

A new process for acetic acid production by direct oxidation of ethylene which was established and commercialized is described. The catalyst system consisting of Pd and heteropoly acid exhibits excellent activity and selectivity. The addition of Se or Te to the catalyst system is effective to suppress the formation of carbon dioxide. This new process is applicable to a plant of a wide range of size corresponding to the local demand. Because this new process produces little waste water, it is very friendly to the environment.     

Chemoselective oxidation of oleanolic acid derivatives with ozone

A method for preparing methyl esters of 12-oxoolean-28-oic and 3,12-dioxoolean-28-oic acids via ozonolysis of oleanolic acid methyl ester in CH₂Cl₂ at –60°C was proposed. It was found that oxidation of 2-cyano3,4-seco-4(23)-oleanenoic acid was chemoselective depending on the amount of ozone used.     

Catalytic asymmetric hydrogenation to access spiroindane dimethyl acetic acid

Asymmetric hydrogenation of achiral spiroindene dimethyl acetic acid 2 with 4% of Ru(II)-Mandyphos in acetone produced (S)-spiroindane dimethyl acetic acid 1 in 86% isolated yield and 96.8:3.2 enantiomeric ratio.     

Kinetics and mechanism of 4-acetoxytoluene oxidation by ozone in an acetic anhydride solution in the presence of manganese bromide catalysts

The kinetics of the reaction of ozone with 4-acetoxytoluene in an acetic anhydride solution in the presence of a manganese bromide catalyst is reported. Under these conditions, the major reaction products are 4-acetoxybenzylidenediacetate (68.0%), 4-acetoxybenzyl acetate (18.5%), and 4-acetoxybenzyl bromide (1.6%). The effect of manganese(II) acetate and potassium bromide on the selectivity of oxidation at the methyl group has been investigated. A probable redox catalysis mechanism explaining the experimental data is considered.     

Catalytic oxidation of thiocyanates in an acid medium

Fundamental aspects of the oxidative destruction of thiocyanates by hydrogen peroxide in an acid medium in the presence of a catalyst, iron(III) ions, was studied. The effect of copper(II) ions on the mechanism and kinetics of SCN-oxidation in the presence of thiosulfates was considered.