Oxidation of sodium (2-14C) acetate with alkaline permanganate

The mechanism and kinetics of the oxidation of sodium acetate with permanganate in alkaline and neutral media, has been investigated using (2-¹⁴C) acetate. The reaction is first order both with respect to permanganate and acetate ions. The initial second order rate constants depend linearly on the square of the hydroxide ion concentration. Arrhenius acitvation energy of the oxidation reaction carried out in 12M NaOH is 24.0 kcal/mole in the temperature interval 50–100°C. The mechanism of the principal path leading to the oxalate formation and the mechanism of the side reaction resulting in the carbon dioxide production has been proposed and discussed.     

Kinetics and mechanism of oxidation of cyclopentanone by N-bromosuccinimide

N-bromosuccinimide oxidation of cyclopentanone in acidic media in presence of mercuric acetate has been made. A zero order dependance to N-bromosuccinimide and a first order dependence to cyclopentanone and hydrogen ion concentration has been observed. Ionic strength, mercuric acetate and succinimide has negligible effect while methanol addition has a positive effect. Various rate parameters have been computed and 1,2-cyclopentanedione identified as the end product. A suitable mechanism in confirmity with the above observations has been proposed.With 2 Figures     

Kinetics of oxidation of butane 2,3-diol by osmium(VIII)

The oxidation of butane 2,3-, propane 1,2-, ethane diol and 2-methoxy ethanol in aqueous alkaline medium by Os(VIII) has been studied. The reaction is base catalyzed and shows first-order kinetics in Os(VIII), whereas the order is less than 1 in butane 2,3-diol [BD]. The rate of oxidation is BD > propane 1,2 > ethane diol ≈ 2-methoxy ethanol. The change in ionic strength has no effect on the rate of reaction. Activation parameters ΔE, PZ, and ΔS* have been evaluated.     

Kinetics and mechanism of the oxidation of some diols by benzyltrimethylammoniumtribromide

The kinetics of oxidation of five vicinal and four non-vicinal diols, and two of their monoethers by benzyltrimethylammonium tribromide (BTMAB) have been studied in 3:7 (v/v) acetic acid-water mixture. The vicinal diols yield the carbonyl compounds arising out of the glycol bond fission while the other diols give the hydroxycarbonyl compounds. The reaction is first-order with respect to BTMAB. Michaelis-Menten type kinetics is observed with respect to diol. Addition of benzyltrimethylammonium chloride does not affect the rate. Tribromide ion is postulated to be the reactive oxidizing species. Oxidation of [1,1,2,2-²H₄] ethanediol shows the absence of a kinetic isotope effect. The reaction exhibits substantial solvent isotope effect. A mechanism involving a glycol-bond fission has been proposed for the oxidation of the vicinal diols. The other diols are oxidized by a hydride ion transfer to the oxidant, as are the monohydric alcohols.     

Kinetics of ruthenium(III) catalyzed and uncatalyzed oxidation of monoethanolamine by <Emphasis Type="Italic">N</Emphasis>-bromosuccinimide

Kinetics of uncatalyzed and ruthenium(III) catalyzed oxidation of monoethanolamine by N-bromosuccinimide (NBS) has been studied in an aqueous acetic acid medium in the presence of sodium acetate and perchloric acid, respectively. In the uncatalyzed oxidation the kinetic orders are: the first order in NBS, a fractional order in the substrate. The rate of the reaction increased with an increase in the sodium acetate concentration and decreased with an increase in the perchloric acid concentration. This indicates that free amine molecules are the reactive species. Addition of halide ions results in a decrease in the kinetic rate, which is noteworthy. Both in absence and presence of a catalyst, a decrease in the dielectric constant of the medium decreases the kinetic rate pointing out that these are dipole—dipole reactions. A relatively higher oxidation state of ruthenium i.e., Ru(V) was found to be the active species in Ru(III) catalyzed reactions. A suitable mechanism consistent with the observations has been proposed and a rate law has been derived to explain the kinetic orders.     

Mechanism of nucleophilic substitution in chromium(III) complexes. II. Formation of Acetatopentamminechromium(III)-ion from aquopentamminechromium(III)-ion in acetic acid — sodium acetate buffer media

The rate of formation of the acetatopentamminechromium(III)ion from the aquopentammine complex in HOAc? NaOAc buffer media has been investigated spectrophotometrically. The results suggest that the reaction occurs by two concurrent paths one of which is independent of acetate ion while the other is first order with respect to acetate ion concentration. The values of the rate constants for both the steps and the corresponding activation parameters, ΔH^≠ and ΔS^≠, have been evaluated. The results are consistent with an S_N1 mechanism for the acetate independent path and an S_N1 IP mechanism for the acetate dependent path. Evidence for ion-pair formation is given.     

Kinetics and mechanism of oxidation of bis(2,4,6-tripyridyl 1,3,5-triazine)iron(II) by vanadium(V), periodate and iodate ions in acetate buffers

The kinetics of oxidation of bis(2,4,6-tripyridyl 1,3,5-s-triazine)iron(II) by vanadium(V), periodate and iodate has been studied in acetate buffers by stopped-flow and spectrophotometric methods. The oxidation reaction of bis(2,4,6-tripyridyl 1,3,5-s-triazine)iron(II) by vanadium(V), periodate and iodate follows first order kinetics for the substrate and oxidant. Hydrogen ion has no significant effect on the rate. A generalized mechanism was proposed for these reactions and these reactions follow the rate law: Rate = k [oxidant] [Fe(tptz)₂ ²⁺].     

The preparation and properties of the acetate complex of trivalent cobalt

A reasonably stable solution of the cobalt(III) acetate complex in glacial acetic acid, containing no water or cobalt(II), has been prepared by the anodic oxidation of the corresponding cobalt(II) acetate solutions at a platinum electrode in a closed system. Cobalt(III) acetate has also been electrolytically prepared without the addition of sodium acetate. Various materials have been tested as membranes because cellophane, which is usually used, has too high electric resistance and too low mechanical strength. The concentration of water in cobalt(III) acetate solutions has been determined by dielectric constant measurements and it has been found that the cobalt(III) acetate stability is almost independent of the water concentration within the range of 0 to 2% of water. In the closed system, the current efficiency was in the range of 60 to 70%; the best reproducibility was obtained using a porous glass membrane.     

Oxidation of butane-1,3-, butane-1,4-, 2-methyl pentane-2,4- and 3-methyl pentane-2,4-diols by cerium(IV) in aqueous acidic medium catalyzed by rhodium(III)

The oxidation kinetics of butane-1,3-diol, butane-1,4-diol, 2-methyl pentane-2,4-diol and 3-methyl pentane-2,4-diol with cerium(IV) catalyzed by rhodium(III) in aqueous sulfuric acid showed a peculiar nature with respect to the variation in oxidant concentration, such that the reaction follows first-order kinetics in [Ce(IV)] at low [Ce(IV)] and then reaches a maximum with increasing [Ce(IV)], beyond which further increase in the oxidant concentration retards the rate. The rate shows direct proportionality with respect to [diol] at low concentrations, becoming independent of [diol] at higher concentrations. The rate is first order in catalyst. Retarding effects are observed when [H⁺] and [Ce(III)] are increased, while [Cl⁻] and hence ionic strength have a positive effect on the rate. Spectroscopic studies confirmed that the primary hydroxyl groups in butane-1,3-diol and butane-1,4-diol resulted in the formation of 3-hydroxy butanal and 4-hydroxy butanal, respectively. In the case of oxidation of the secondary hydroxyl groups in 2-methyl pentane-2,4-diol and 3-methyl pentane-2,4-diol, the products of oxidation were 4-hydroxy-4-methyl pentan-2-one and 4-hydroxy-3-methyl pentan-2-one, respectively.     

Improved Synthesis of Tricyclo (5.2.1.04,10) Decane-2,5,8-Trione by a Pauson-Khand Intramolecular Bis-Annulation

The title compound 1 has been synthesized from diol 3a, either directly or after protection of the two hydroxy groups as benzyl ethers, by an intramolecular Pauson-Khand bis-annulation, followed by catalytic hydrogenation and oxidation in overall yields ranging from 15% (free diol) to 35% (dibenzyl ethers).     

聚醚的氧化及其接枝共聚合的研究

聚醚在空气氧化或在H_2O_2存在下的光氧化条件下,很容易被氧化成过氧化氢物。控制适度的氧化时间和过氧化氢物浓度,可避免发生链的断裂。聚醚过氧化氢物与亚铁盐或N,N-二甲基对甲苯胺作用,可在较低温度下引发烯类单体接枝共聚,并可避免均聚反应。接枝率随过氧化氢物浓度的增加而增加,随反应时间延长而提高,改变N,N-二甲基对甲苯胺的浓度,接枝率也随之改变。共聚产物分离提纯后,经IR光谱测定和元素分析,均证实了产物为一接枝共聚物。聚醚的氧化及接枝共聚的实验,为聚醚氨酯的氧化和接枝共聚的机理的研究,提供了基本数据。     

Solid-phase extraction gas chromatography-ion trap-mass spectrometry qualitative method for evaluation of phenolic compounds in virgin olive oil and structural confirmation of oleuropein and ligstroside aglycons and their oxidation products

Phenolic compounds in Spanish virgin olive oil were analyzed by GC-MS after an SPE diol cartridge extraction and clean-up procedure. Posterior derivatization to trimethylsilyl (TMS) ethers using a mixture of hexamethyldisilazane:dimethylclorosilane (HMDS:DMCS) in pyridine (3:1:9) was performed. Several compounds were detected and 21 of them were identified. Free phenols such as hydroxytyrosol, tyrosol, tyrosyl and hydroxytyrosyl acetate, and aldehydic and dialdehydic forms of elenolic acid linked to tyrosol and hidroxytyrosol were the most abundant compounds. Likewise, oxidation products coming from the aldehydic and dialdehydic forms of elenolic acid, and of ligstroside and oleuropein aglycons, were detected, and their structure confirmed by other mass spectrometry technique, i.e., HPLC-APCI-MS. Individual oxidation products were isolated from an oxidized sample by preparative HPLC, converted to TMS ethers and re-analyzed by GC-MS. When necessary and for identification purposes, selective ion monitoring, namely, GC-MS-SIM, was employed. This is the first time that structures of oxidized forms are determined by GC-MS.     

Kinetics and mechanism of oxidation of 1,4-butanediol by chromium(VI) in acid perchlorate medium

Summary The kinetics of oxidation of 1,4-butanediol by chromium(VI) was studied in acid perchlorate medium and the oxidation product of the diol was identified as 4-hydroxybutanal. The kinetic rate law observed accounted for the complex dependence of the hydrogen ion k=(k₂K₁[H+]+k₃K₁K₂[H+]²)/(1+K₁[H]+) where k is the observed second-order rate constant.     

Kinetics and Mechanism of Oxidation of Adipic Acid by Ce(IV) Ion in Acidic Medium

Kinetic study of oxidation of adipic acid by Ce(IV) ion in aqueous solution of sulphuric acid shows that the reaction follows first order kinetics in both Ce(IV) and adipic acid and the over all reaction order ascertained is two. The specific rate constant increases with an increase in the concentration of adipic acid. Effects of hydrogen ion concentration, bisulphate ion and temperature have been studied in detail. Various kinetic parameters have been computed. The experimental findings are consistent with the mechanism involving rapid resersible formation of an activated complex between Ce(IV) and adipic acid followed by a rate determining step involving C-C bond fission.     

Voltammetric study of the oxidation of quercetin and catechin in the presence of cyanide ion

The reaction of electrochemically generated o-benzoquinones from oxidation of quercetin and catechin as Michael acceptors with cyanide ion as nucleophile has been studied using cyclic voltammetry. The reaction mechanism is believed to be EC; including oxidation of catechol moiety of these antioxidants followed by Michael addition of cyanide ion. The observed homogeneous rate constants (k _obs) for reactions were estimated by comparing the experimental voltammetric responses with the digitally simulated results based on the proposed mechanism. The effects of pH and nucleophile concentration on voltammetric behavior and the rate constants of chemical reactions were also described.     

Kinetics and mechanism of the oxidation of α-amino acids by n-bromoacetamide

The kinetics of the oxidation of eight α-amino adds by N-bromoacltanude have been studied in aqueous perchloric acid solution. The main products of the oxidation are the corresponding carbonyl compounds. The reaction is of first order with respect to the oxidant and the amino acid. The rate of oxidation decreases linearly with an increase in hydrogen ion concentration. The rate is decreased by the addition of acetamide. The oxidation of deuteriated glycine indicated the absence of a primary kinetic isotope effect. The reaction rate has been determined at different temperatures and activation parameters have been calculated. Hypobromous add has been postulated as the reactive oxidizing species. A rate-determining reaction of the neutral amino add and hypobromous add to give an N-bromo derivative has been proposed. The slow step is followed by a fast decomposition of the N-bromo derivative to yield the ultimate product.     

Kinetics and Mechanism of Oxidation of 1-Phenylsemicarbazide by Peroxydisulphate

Kinetics of oxidation of 1-phenylsemicarbazide (PSC) by peroxydisulphate ion (PDS) have been carried out where by the pseudo first order condition was verified at large excess of PDS concentration. The rate of the reaction was followed spectrophotometrically, The stoichiometry was found to be 1:1 where 1-phenylazoformamide is the oxidation product. The effect of acidity on the rate of oxidation was investigated for different temperatures. The parameters of activation ΔG*, ΔH* and ΔS* were computed for both hydrogen ion depedent and hydrogen ion independent reaction pathes. A free radical mechanism was proposed.     

Kinetics of the oxidation of aliphatic aldehydes by Os(VIII) in alkaline solution

Kinetics of oxidation of six aliphatic aldehydes by Os(VIII) in alkaline solutions have been studied. The reaction is of first order with respect to each of the aldehyde and Os(VIII). The pseudo-first order rate constants decreased with an increase in the concentration of hydroxyl ions. The oxidation of deuterioacetaldehyde (MeCDO) exhibited a substantial primary kinetic isotope effect. Separate rate constants for the oxidation of hydrate and free aldehyde forms have been evaluated. The aldehyde hydrate is postulated as the active reductant. Ionic strength has no noticable effect on the rate. The rate-determining step is, therefore, postulated to be a bimolecular reaction between the aldehyde hydrate and [OsO₄(OH)₂]^?2. The value of the limiting rate constant exhibited an excellent correlation with Taft σ* values; reaction constant being negative. A mechanism involving transfer of a hydride ion from the aldehyde hydrate to Os(VIII) has been proposed.     

Kinetics and mechanism of the liquid-phase reaction of 2,4-dinitrotoluene with ozone in the presence of manganese(II) acetate

The kinetics and the mechanism of the liquid-phase oxidation of 2,4-dinitrotoluene with ozone in the presence of manganese(II) acetate have been investigated. The major products of 2,4-dinitrotoluene oxidation with ozone in acetic anhydride are 2,4-dinitrobenzyl acetate (65.8%) and 2,4-dinitrobenzylidene diacetate (18.8%). The effect of the manganese(II) acetate concentration on the selectivity of substrate oxidation at the methyl group is reported. A redox catalysis mechanism providing an explanation to experimental data is considered.     

Catalyzed liquid-phase oxidation of dialkylthiophenes

The oxidation of 3-methyl-2-ethylthiophene with molecular oxygen in glacial acetic acid in the presence of a cobalt-bromide catalyst was investigated. It was established that there is a dependence of the rate of oxidation of this compound on its concentration, on the catalyst (cobalt acetate) concentration, and on the initiator (NaBr) concentration. The principal oxidation products are 3-methyl-2-acetothienone (III) and 1-(3-methyl-2-thienyl) ethyl acetate, which were isolated and characterized. The reactivity of 3-methyl-2-ethylthiophene in the oxidation reaction is higher than that of 4-methyl-2-ethylthiophene.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 758–761, June, 1981.