对叔丁基甲苯的直接电解氧化

由对叔丁基甲苯合成对叔丁基苯甲醛,主要有化学氧化法、空气(或氧气)催化氧化法和电化学氧化法。化学氧化法通常使用二氧化锰作氧化剂,在浓硫酸中氧化合成对叔丁基苯甲醛。此法的主要缺点是产生大量的硫酸锰,需回收处理。另外,浓硫酸介质腐蚀设备且对环境有一定影响。空气催化氧化     

Study on dynamics characteristics of wet air oxidation of non-ionic surfactants

Wet air oxidation is an effective method to deal with highly concentrated nondegradable emulsification wastewater which contains non-ionic surfactants. This article illustrates our investigation on dynamic characteristics of wet air oxidation of typical non-ionic surfactants like polyether, phenol ether and widely used alcohol ether. The experimental results indicated that the oxidation rate of polyether, phenol ether and alcohol ether obviously ascended as the temperature rose. A good oxidation effect was available at 240℃. The TOC removal rate could reach 88.0%, 94% and 91.5%, after 125 min reaction. Alcohol ether was prone to an easier oxidation compared with polyether and phenol ether when the temperature was 220℃ or below. The oxidation rate of alcohol ether was higher than that of polyether at 160℃, while the oxidation rate of polyether was higher than that of phenol ether between 180℃ and 220℃. During the later period of the reaction at 240℃, the rate of phenol ether was higher than that of alcohol ether, which was still higher than that of polyether. Partitioned first order kinetics model analy-sis showed that the apparent activation energy of alcohol ether was lower than that of both polyether and phenol ether in the leading stage and lagging stage, and it was easy to acquire a higher oxidation rate for alcohol ether at low temperature. Three parameter general dynamics model analyses showed that the reason why the oxidation rate of polyether was lower than that of alcohol ether was that the oxidation of polyether was more apt to be converted to intermediate production than that of alcohol ether, whereas between 200℃ and 220℃, the direct oxidation rate of polyether and the oxidation rate of intermediate product were obviously lower than that of alcohol ether. The apparent activation energy of direct and indirect oxidation of polyether was 43.37 and 60.45 kJ?mol?1, respectively, while the corre-sponding apparent activation energy of alcohol was 38.74 and 58.09 kJ·mol?1, respectively.     

添加甲醇对二甲醚/空气二阶段燃烧过程的影响

采用一维层流预混火焰模型对二甲醚/甲醇/空气预混气体的流动反应过程进行了数值模拟, 考察甲醛、甲酸等污染物的生成规律. 结果表明: 在低流速下, 添加甲醇能够改变二甲醚反应途径, 抑制二甲醚的低温氧化反应. 当添加和二甲醚等质量的甲醇时, 二甲醚几乎不发生低温氧化反应, 生成的OH自由基减少是导致其发生的主要原因. 随着甲醇添加量的增加, 甲酸排放指数EI_HCOOH迅速降低, 而甲醛排放指数EI_HCHO在少量增加后持续降低. 添加适量甲醇能够同时降低这两种污染物的排放指数.     

STUDIES ON THE OXIDATION AND GRAFT COPOLYMERIZATION OF POLYETHERS

Polyethers could form hydroperoxide under air-oxidation or photo-oxidation in the presence of H_2O_2. The scission of ether linkage induced by moderate oxidation was prevented by controlling the reaction time and hydroperoxide concentration. The oxidation rate was affected by the end groups of polyethers. The decreasing order of oxidation rate for various poly(tetramethylene ether) glycol derivatives having different end groups are as follows: poly(tetramethylene ether) glycol (PTMG)>poly(tetramethylene ether)acetate (PTMGAC) >poly(tetramethylene ether) phenyl carbamate (PTMGPC). The urethane end groups in PTMGPC increase the resistance toward oxidation. Polyether hydroperoxide reacts with ferrous ion or N,N-dimethyl toluidine (DMT) to form polymericoxy radical which then initiates the graft copolymerization of vinyl monomers at low temperature, and was devoid of homopolymerization. The copolymer after separation and purification was proved to be a graft one by IR analysis and elemental analysis.     

Theoretical Study on the Dark Oxidation Reaction Mechanism of Ethers

1 INTRODUCTION Ethers are a kind of organic compounds that are easily oxidized under the conditions of lacking light and any additional excitement. According to dif- ferent mechanisms, the oxidation reactions could be classified into two types: photooxidation reaction and dark oxidation reaction. The former is the reaction with excited state oxygen molecule (singlet state), while the latter is the reaction with ground state oxygen molecule (triple state) without illuminance or any exciter…     

Anodic cyclization reactions: capitalizing on an intramolecular electron transfer to trigger the synthesis of a key tetrahydropyran building block

An anodic cyclization reaction between an enol ether radical cation and an oxygen nucleophile has been used to make a tetrahydropyran building block for the C(10)-C(16) portion of bryostatin. The oxidative cyclization was successful despite the presence of a thioacetal group that has a lower oxidation potential than the enol ether. Experimental evidence suggested that the reaction proceeded through an initial oxidation of the thioacetal followed by an intramolecular electron transfer to form the enol ether radical cation that was subsequently trapped by the oxygen nucleophile. The formation of the desired cyclic product could be explained using the Curtin-Hammett principle. By taking advantage of the intramolecular electron-transfer reaction, we used the presence of a thioacetal in an electrolysis substrate to selectively oxidize a proximal enol ether in the presence of an otherwise identical but more remote enol ether.     

Heterogeneous catalytic aerobic oxidation behavior of Co–Na heterodinuclear polymeric complex of Salen-crown ether

A new kind of Co–Na heterodinuclear polymer complex based on Salen Schiff base and crown ether has been successfully prepared by condensation polymerization. Its catalytic behavior for aerobic oxidation of cyclohexene, alkylbenzenes and linear aliphatic olefins was studied in the absence of any solvents or reducing agents under mild conditions. The oxidation of cyclohexene catalyzed by the above catalyst proved to be a simple and efficient method for obtaining 2-cyclohexen-1-one (CO) and 2-cyclohexen-ol (OH) in a high selectivity. Kinetics of the oxidation was also investigated. The results showed that the aerobic oxidation of cyclohexene catalyzed by Salen-crown ether heterodinuclear polymer complex follows a radical chain aerobic oxidation mechanism. This oxidation system is also efficient in the oxidation of alkylbenzenes and linear aliphatic olefins, which afforded corresponding benzylic oxidation products and epoxides, respectively.     

醚的初始暗氧化反应机理的研究

有机化合物的空气氧化是一个历史悠久的研究课题。早在1851年Schonbein[1]就注意到醚在空气中会被氧化产生过氧化物。本世纪初,Clover和Milas分析了醚的空气氧化产物,并且对醚的氧化机理,进行了研究。     

Liquid-phase oxidation of dibenzyl ether by atmospheric oxygen in the presence of homo- and heteroligand pivalate and 3,5-dimethylpyrazolate complexes of 3<Emphasis Type="Italic">d</Emphasis> metals

The main products of the reaction in the presence of homo- and heteroligand pivalate and 3,5-dimethylpyrazolate mono-, bi-, and trinuclear complexes of Co, Cu, Ni, and Zn are the hydroperoxide, benzaldehyde, and benzoic acid. The effect of the composition and structure of the complexes on the conversion of the substrate, the selectivity of the process, and the possibility of alternative routes to the oxidation of dibenzyl ether is discussed.     

Mechanistic investigation of substrate oxidation by Ce(IV) reagents in acetonitrile

Rates and activation parameters for the Ce(4+)-mediated oxidation of a beta-keto ester, a beta-diketone, and a beta-keto silyl enol ether were determined in acetonitrile. In the case of the dicarbonyls, the enol content of the substrate impacts the rate of oxidation by Ce(4+), predominantly through contributions from DeltaH(). For the silyl enol ether, the transition state for oxidation by Ce(4+) is substantially more ordered than it is for the beta-keto ester or the beta-diketone.     

Oxidation of organic sulfur compounds with hydrogen peroxide in the presence of crown ethers

Hydrogen peroxide oxidizes methyl phenyl sulfide and benzothiophene in the presence of crown ethers to the corresponding sulfoxides and sulfones. The oxidation is retarded by amino acids. UV and NMR spectroscopies show that, at the initial stage of oxidation, complexation occurs between crown ether, hydrogen peroxide, and sulfide, as well as between crown ether and amino acid.     

Initiated oxidation of dibutyl ether in the presence of inhibitors

It was found that unlike ionol, amines effectively inhibit the oxidation of dibutyl ether. The stoichiometric inhibition coefficient for amines is close to two. During the initiated oxidation of dibutyl ether in the presence of inhibitors, an exchange takes place of cyanoisopropyl peroxy radicals for the peroxy radicals of dibutyl ether. The mechanism of the reaction with p-phenylenediamine (p-PDA) probably consists in the formation of a fairly stable complex consisting of an amine molecule and two peroxy radicals. This reaction does not result in the formation of a hydroperoxide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1268–1273, June, 1990.     

Characterization of double oxide system Cu-Cr-O supported on <Emphasis Type="Italic">γ</Emphasis>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

Series of alumina supported chromium-copper catalysts were prepared by co-impregnation method. The samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and UV-visible diffuse reflectance spectroscopy. Dispersion and porosity was also obtained. The experimental and catalytic test results have drawn a conclusion that an interaction between copper and chromium ions takes place. This interaction is responsible for the enhanced catalytic activity of studied catalysts in reaction of total oxidation of industrial formaldehyde production exhaust gas, which contains CO, dimethyl ether and methanol as main components. The article is published in the original.     

Total synthesis of brevetoxin B

The convergent total synthesis of brevetoxin B (1) has been achieved. The intramolecular allylation of the O,S-acetal 20, prepared from the alpha-chlorosulfide 17 and the alcohol 5, was carried out using AgOTf as a Lewis acid to give the diene 21, predominantly. Ring-closing metathesis of 21 with the Grubbs catalyst 23 afforded the hexacyclic ether 25 which was converted to the A-G ring segment 2 through several steps. The intramolecular allylation of the alpha-acetoxy ether 42, prepared from 2 and the J-K ring segment 3, followed by ring-closing metathesis provided the polycyclic ether framework 44. A series of reactions of 44, including oxidation of the A ring, deprotection of the silyl ethers, and selective oxidation of the resulting allylic alcohol, furnished 1.     

氮杂冠醚取代单Schiff碱过渡金属配合物催化氧化对二甲苯研究

本文将苯并-10-氮杂-15-冠-5或吗啉基取代的单Schiff碱过渡配合物作为催化剂,在常压和120℃条件下,以空气为氧源,研究了对二甲苯催化氧化反应。实验探讨了Schiff碱配合物中心金属离子、Schiff碱配体中挂接的氮杂冠醚环、配体芳环上取代基和反应时间等对对二甲苯催化氧化反应的影响。实验结果表明:Schiff碱配合物中氮杂冠醚的存在能显著缩短反应诱导期,提高催化反应活性和产物选择性;Schiff碱Mn(III)配合物比Schiff碱Co(II)具有更高的催化反应活性;氮杂冠醚Schiff碱Mn(III)配合物对于二甲苯的催化氧化反应转化率大于60%,对甲苯甲酸产物的选择性均高于70%。     

氮杂冠醚取代非对称双Schiff碱配合物催化氧化对二甲苯研究

将一系列苯并-10-氮杂-15-冠-5或吗啉基取代的不对称双Schiff碱配合物作为催化剂,在常压和120℃条件下用于催化氧化对二甲苯研究。探讨了Schiff配合物中心金属离子、Schiff碱配体中挂接的氮杂冠醚环、配体芳环上取代基等对催化氧化对二甲苯反应活性及其氧化产物选择性的影响。实验结果表明:配合物中氮杂冠醚的存在能显著缩短反应诱导期、提高催化活性和选择性;Schiff碱Mn(Ⅲ)配合物比Schiff碱Co(Ⅱ)和Schiff碱Cu(Ⅱ)具有更高的催化活性;氮杂冠醚Schiff碱Mn(Ⅲ)配合物催化氧化二甲苯的转化率和产物选择性分别达75%和90%。     

Synchrotron Photoionization Study of the Diisopropyl Ether Oxidation

Scientific evidence has shown oxygenates help to reduce dangerous pollutants arising from burning fossil fuel in the automotive sector. For this reason, their use as additives has spread widely. The aim of this work consists in providing a comprehensive identification of the main primary oxidation products of diisopropyl ether (DIPE), one of the most promising among etheric oxygenates. The Cl-initiated oxidation of DIPE is examinated by using a vacuum ultraviolet (VUV) synchrotron radiation at the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory (LBNL). Products are identified on the basis of their mass-to-charge ratio, shape of photoionization spectra, adiabatic ionization energies, and chemical kinetic profiles, at three different temperatures (298, 550, and 650 K). Acetone, propanal, propene, and isopropyl acetate have been identified as major reaction products. Acetone is the main primary product. Theoretical calculations using the composite CBS-QB3 method provided useful tools to validate the postulated reaction mechanisms leading to experimentally observed species. The formation of other species is also discussed.     

Preliminary observations on the high temperature oxidation of ethyl tert-butyl ether

The high temperature oxidation of ethyl tert-butyl ether (ETBE) with oxygen in argon diluent has been studied in reflected shock waves over the temperature range 1160 to 1830 K, with pressures of 3.5 bar and with varying equivalence ratios from 0.3 to 2.4. Measurements of the ignition delay times, characterized by chemiluminescence and pressure rise, show that the rate of oxidation is very similar to that of methyl tert-butyl ether.     

Synthesis,O_2-binding ability and catalytic oxidation performance of cobalt(Ⅱ) complexes with dihydroxamic acid functionalized N-pivot lariat ethers

Novel Co(Ⅱ) complexes with dihydroxamic acids functionalized N-pivot lariat ether CoL~1-CoL~4 were synthesized and characterized.Their oxygenation constants(ln K_(O2)) and thermodynamic parameters(△H°,△S°) were measured.And their catalytic performance in oxidation of p-xylene to p-toluic acid(PTA) was investigated.The enhancement of O_2-binding and catalytic oxidation activity by the oxa aza crown ether ring of the cobalt complexes were discussed.     

两种煤的次氯酸钠水溶液降解产物的分离与分析

两种煤于温和条件下在次氯酸钠水溶液中进行降解,所得水溶液经酸化后,水溶物依次用乙醚、CS2、石油醚、乙酸乙酯和苯进行分级萃取,萃取物经重氮甲烷酯化后用GC/MS分析。结果发现氯代物、脂肪酸和芳酸是煤的NaOCl水溶液降解的典型化合物,不同极性溶剂分级萃取可以实现产物的初步族组分分离。通过该研究建立煤的次氯酸钠氧化反应混合物有效分离和分析的方法,为煤的高附加值利用提供有效的途径。