Phenols In Acetonitrile Research Articles

One-pot, simple, and facile synthesis of 4-(3-benzylbenzo[d]thiazol-2(3H)-ylidene)-cyclohexa-2,5-dien-1-one derivatives via a novel three-component reaction

In this study, a series of 4-(3-benzylbenzo[ d]thiazol-2(3 H)-ylidene)-cyclohexa-2,5-dien-1-one derivatives are efficiently synthesized in excellent yields by reactions of 2-chlorobenzothiazole, benzyl bromides, and phenols in acetonitrile under reflux and catalyst-free conditions in the presence of triethylamine for 2 h. The structures of the products are characterized by NMR, IR, EI-MS, and elemental analyses.

Effect of Anodic Pretreatment on the Performance of Glassy Carbon Electrode in Acetonitrile and Electrooxidation of Para-substituted Phenols in Acetonitrile on Platinum and Glassy Carbon Electrode

In the first part of the work electropolymerisation of phenol was studied at glassy carbon electrode. Rapid fouling of its surface indicated the formation of coherent poly(phenyleneoxide) layer which was demonstrated by the repeated cyclic voltammetric scans. Effect of anodic pretreatment potential in acetonitrile solvent was also investigated and the results showed that at potentials higher than 2 V glassy carbon electrode becomes deactivated. Preanodisation of glassy carbon electrode at 3 V in acetonitrile resulted in diminished anodic peak currents by phenols. It was due to the partial deactivation of electrode surface and its extent increased with the pretreatment time. The electrooxidation of para-substituted phenols (p-Cl-phenol, p-NO2-phenol, p-tertbutylphenol, p-methoxyphenol) in acetonitrile resulted in no fouling layer on platinum electrode and the peak currents were significantly higher than in the first scan of unsubstituted phenol in the same concentration. Glassy carbon deactivated continuously by repeating the scans due to the solvent and bonding of products on the surface.

Hydroxylation of benzene to phenol on Cu x O y @C with hydrogen peroxide

Cu x O y @C was directly prepared with glucose and a copper(II) salt by a one-pot hydrothermal method. The catalyst was characterized by XRD, TG, XPS, FT-IR and SEM. The catalytic performance for the hydroxylation of benzene to phenol in acetonitrile with hydrogen peroxide as the oxidant was investigated. The features of the reaction system with the prepared heterogeneous catalyst were studied by various reaction parameters including reaction temperature, catalyst amount, hydrogen peroxide amount, reaction time, effect of solvents and additives. The result showed that solvent and additive affect the yield of phenol.

Modulation of Phenol Oxidation in Cofacial Dyads.

The presentation of two phenols on a xanthene backbone is akin to the tyrosine dyad (Y730 and Y731) of ribonucleotide reductase. X-ray crystallography reveals that the two phenol moieties are cofacially disposed at 4.35 Å. Cyclic voltammetry reveals that phenol oxidation is modulated within the dyad, which exhibits a splitting of one-electron waves with the second oxidation of the phenol dyad occurring at larger positive potential than that of a typical phenol. In contrast, a single phenol appended to a xanthene exhibits a two-electron process, consistent with reported oxidation pathways of phenols in acetonitrile. The perturbation of the phenol potential by stacking is reminiscent of a similar effect for guanines stacked within DNA base pairs.

ChemInform Abstract: Facile One‐Pot Synthesis of VxOy@C Catalysts Using Sucrose for the Direct Hydroxylation of Benzene to Phenol.

VxOy@C catalysts were prepared from sucrose and NH4VO3 by a one-pot hydrothermal method. They showed satisfactory catalytic performance for the hydroxylation of benzene to phenol in acetonitrile using oxygen as the oxidant.

Facile one-pot synthesis of VxOy@C catalysts using sucrose for the direct hydroxylation of benzene to phenol

VxOy@C catalysts were prepared from sucrose and NH4VO3 by a one-pot hydrothermal method. They showed satisfactory catalytic performance for the hydroxylation of benzene to phenol in acetonitrile using oxygen as the oxidant.

Hydroxylation of Benzene by Activated Carbon Catalyst

Phenol is widely used in industry. The hydroxylation of benzene to phenol can meet the increasing requirement for phenol and green chemistry. Commercial wood-based activated carbon was treated by different methods, including oxidation by nitric acid and hydrogen peroxide and thermal treatment at different temperatures, and used as the catalyst for the hydroxylation of benzene to phenol in acetonitrile using H 2 O 2 as oxidant. The mechanism of the hydroxylation was also investigated. The activated carbon samples were characterized by Boehm titration, nitrogen adsorption, and X-ray photoelectron spectroscopy. The pH had a significant effect on the phenol yield. The effect of benzene adsorption was also investigated. Several model compounds with oxygen groups were used as catalysts for the hydroxylation of benzene. The reaction between phenolic hydroxyl and quinone on the surface of activated carbon was responsible for the hydroxylation of benzene to phenol when it activated H 2 O 2 to form the hydroxyl radical. Activated carbon was an efficient and stable catalyst and a maximum phenol yield of 14.4% was obtained under the optimal reaction conditions. 将市售活性炭经过硝酸 过氧化氢及不同温度进行处理后用于苯的羟基化反应, 并研究了活性炭催化苯羟基化反应机理. 用 Boehm 滴定, N 2 吸附-脱附及 X 射线光电子能谱对活性炭进行了表征. 结果表明, 反应体系的 pH 对催化剂活性具有重要的影响, 活性炭对苯的吸附受表面含氧基团含量的影响. 模型化合物反应结果表明, 活性炭表面的酚羟基和羰基是反应的活性位, 两者可相互转化, 并在一定的 pH 条件下达到平衡, 该转化使得 H 2 O 2 活化为羟基自由基, 进而与苯反应生成苯酚. 在苯羟基化反应中, 活性炭表现出良好且稳定的催化性能, 苯酚收率可达 14.4%. The reaction between phenolic hydroxyl and quinone on the surface of activated carbon activated H 2 O 2 to form a OH radical, which then reacts with benzene to form phenol.

Direct Synthesis of Phenol from Benzene on an Activated Carbon Catalyst Treated with Nitric Acid

Commercially available coal-based activated carbon was treated by nitric acid with different concentrations and the resultant samples were used as catalysts for the direct hydroxylation of benzene to phenol in acetonitrile. Boehm titration, X-ray photoelectron spectroscopy, scanning electron microscope coupled with an energy dispersive X-ray microanalyzer, and Brunauer-Emmett-Teller method were used to characterize the samples. The number of carboxyl groups on the surface was found to be the main factor affecting the catalytic activity. An optimum catalytic performance with a yield of 15.7% and a selectivity of 87.2% to phenol was obtained.

The role of low levels of water in the electrochemical oxidation of α-tocopherol (vitamin E) and other phenols in acetonitrile

The phenol, α-tocopherol, can be electrochemically oxidised in a -2e(-)/-H(+) process to form a diamagnetic cation that is long-lived in dry organic solvents such as acetonitrile and dichloromethane, but in the presence of water quickly reacts to form a hemiketal. Variable scan rate cyclic voltammetry experiments in acetonitrile with carefully controlled amounts of water between 0.010 M-0.6 M were performed in order to determine the rate of reaction of the diamagnetic cation with water. The water content of the solvent was accurately determined by Karl Fischer coulometric titrations and the voltammetric data were modelled using digital simulation techniques. The oxidation peak potential of α-tocopherol measured during cyclic voltammetry experiments was found to shift to less positive potentials as increasing amounts of water (0.01-0.6 M) were added to the acetonitrile, which was interpreted based on hydrogen-bonding interactions between the phenolic hydrogen atom and water. Several other phenols were examined and they displayed similar voltammetric features to α-tocopherol, suggesting that interactions of phenols with trace amounts of water were a common occurrence in acetonitrile. The H-bonding interactions of α-tocopherol with water were also examined via NMR and UV-vis spectroscopies, with the voltammetric and spectroscopic studies extended to include other coordinating solvents (dimethyl sulfoxide and pyridine).

Synthesis and Characterization of Polymer Anchored Cu(II) Complexes: Heterogeneous Catalysts for Preparation of Diaryl Ethers

AbstractPolymer anchored Cu(II) Schiff base complexes have been prepared and characterized by using scanning electron microscope (SEM), elemental analysis, atomic absorption spectroscopy (AAS), thermogravimetric analysis (TGA), spectrometric methods like diffuse reflectance spectra of solid (DRS) and fourier transform infrared spectroscopy (FTIR). These catalysts show excellent catalytic activity in the O‐arylation reaction of aryl halides with phenol in acetonitrile using Cs2CO3 at 70°C under an open air condition to give diaryl ethers in high yields. The effects of various parameters such as solvent, catalyst from different copper salt and base on the reaction system have been studied. The reaction is applicable to a wide variety of substituted aryl halides and phenols with different steric and electronic properties. These catalysts are recovered by simple filtration and the reusability experiments show that these catalysts can be used five times without much loss in the catalytic activity.

A laser flash photolysis and theoretical study of hydrogen abstraction from phenols by triplet α-naphthoflavone

The hydrogen abstraction (HA) reaction by the triplet of alpha-naphthoflavone (1) has been investigated experimentally by the use of laser flash photolysis (LFP) and theoretically with density functional theory (DFT) and atoms in molecules (AIM). The triplet excited state of 1, in acetonitrile, has an absorption maximum at 430 nm and lifetime of 10 micros. The quenching rate constants for the triplet of 1 with 1,4-cyclohexadiene, substituted phenols and amines were determined. The low reactivity of this ketone with respect to HA from 1,4-cyclohexadiene is in accord with a pi,pi* excited state. HA from phenols in acetonitrile is proposed to occur in a diffusion controlled reaction from free phenol based upon the determination of the Abraham beta(H)(2) value for acetonitrile and correction of the quenching rate constants for hydrogen bonding of the phenols to acetonitrile. A molecular orbital analysis of the triplet (SOMO and SOMO-1) of 1 reveals contributions from the carbonyl oxygen atom, but principally from the alpha-carbon and the associated pi-bond network, consistent with a pi,pi* excited state. From a thermodynamic point of view, the triplet HA from phenol to oxygen of the carbonyl group is 17 kcal mol(-1) less demanding than the transfer to the alpha-carbon, consistent with the acidic nature of the phenolic hydrogen atom. DFT and AIM analysis of the hydrogen abstraction reaction reveals that the transition state (TS) is pseudo-symmetrically polarized and that HA in the hydrogen bonded exciplex occurs in a concerted manner but not necessarily by simultaneous electron and proton transfer.

Capillary electrophoresis of methyl-substituted phenols in acetonitrile

The separation of mono- and dimethylphenols by capillary electrophoresis in pure acetonitrile was investigated. In acetonitrile, uncharged phenols interact with background electrolyte anions forming negatively charged complexes, which can be separated from each other by capillary electrophoresis. The background electrolyte anions tested were acetate, bromide and chloride. The calculated formation constants for phenol–anion complexes were highest with acetate and smallest with bromide. Complex formation was found to be sensitive to traces of water in the background electrolyte. The separation of methylphenols was also carried out in acetonitrile at high pH using background electrolytes prepared from diprotic acids and tetrabutylammonium hydroxide. At high pH the phenols were partly dissociated, providing an additional mechanism for the separation. All methylphenols were separated with the use of malonate background electrolyte. However, this approach was prone to interference from methanol resulting from the tetrabutylammonium hydroxide solution.

Antithetical product situation in the femtosecond and nanosecond photoionization of sterically hindered phenols in non-protic solvents

The photoionization of sterically hindered phenols in acetonitrile or n-butyl chloride solution gives apparently contradictory results performing biphotonic ionization with femtosecond as well as nanosecond UV lasers: in the first case phenol radical cations were found whereas in the latter one only phenoxyl radicals were detected. This is explained by non-resonant and resonant ionization pathways. Furthermore, the deprotonation rate of the phenol radical cations in acetonitrile in the presence of water traces could be determined as to be diffusion controlled ((3 to 7 )×10 9 dm 3 mol −1 s −1) which could not be observed till now because of its extreme p K a value of ≪−1.

Synthesis of 3‐phenoxy‐1,3‐dihydro‐1‐isobenzofuranones by palladium‐catalyzed carbonylative cyclization of 2‐bromobenzaldehyde with phenols

Abstract2‐Bromobenzaldehyde reacts with phenols in acetonitrile under carbon monoxide pressure in the presence of a catalytic amount of bis(triphenylphosphine)palladium(II) chloride to afford the corresponding 3‐phenoxy‐1,3‐dihydro‐1‐isobenzofuranones in high yields.

Acid-catalyzed rearrangement of K-region arene oxides: observation of ketone intermediates and a sterically induced change in rate-determining step

K-region arene oxides rearrange to phenols in acetonitrile in two acid-catalyzed steps: rapid rearrangement of the arene oxide to positionally isomeric keto tautomers of K-region phenols, followed by slow enolization. Accumulation of the ketones, proposed intermediates in the acid-catalyzed solvolyses of arene oxides in aqueous solution, allowed their direct spectroscopic observation and characterization for the first time under solvolytic conditions. Rate constants and products are reported for the K-region arene oxides of benzo[a]anthracene, its 1-, 4-, 7-, 11-, 12-methyl, and 7,12-dimethyl substituted derivatives, benzo[a]pyrene, benzo[c]phenanthrene, 3-bromophenanthrene, chrysene, dibenz[a,h]anthracene, phenanthrene, and pyrene

ChemInform Abstract: Nucleophilic Substitution at Trigonal Carbon. Part 4. Substituent Effects in the Reactions of Aliphatic Acyl Chlorides (I) with Methanol and Phenol in Acetonitrile

ChemInformVolume 19, Issue 44 Preparative Organic Chemistry ChemInform Abstract: Nucleophilic Substitution at Trigonal Carbon. Part 4. Substituent Effects in the Reactions of Aliphatic Acyl Chlorides (I) with Methanol and Phenol in Acetonitrile D. N. KEVILL, D. N. KEVILL Dep. Chem., North. Ill. Univ., DeKalb, IL 60115, USASearch for more papers by this authorC.-B. KIM, C.-B. KIM Dep. Chem., North. Ill. Univ., DeKalb, IL 60115, USASearch for more papers by this author D. N. KEVILL, D. N. KEVILL Dep. Chem., North. Ill. Univ., DeKalb, IL 60115, USASearch for more papers by this authorC.-B. KIM, C.-B. KIM Dep. Chem., North. Ill. Univ., DeKalb, IL 60115, USASearch for more papers by this author First published: November 1, 1988 https://doi.org/10.1002/chin.198844101Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume19, Issue44November 1, 1988 RelatedInformation

Nucleophilic substitution at trigonal carbon. Part 4. Substituent effects in the reactions of aliphatic acyl chlorides with methanol and phenol in acetonitrile

A previous study of the methanolysis and phenolysis of acetyl chloride in acetonitrile has been extended to the influence of the substitution of up to two chlorine atoms or up to three methyl groups into the acetyl chloride. For each of the substrates so obtained, the methanolysis continues to exhibit pathways with both second-and third-order kinetics. The introduction of up to two methyl groups has only a minor influence but an appreciable fall in the magnitude of both rate coefficients is observed upon introduction of the third methyl group. The introduction of chlorine atoms leads to fairly large accelerations, and a tightening of the loose SN2 transition state or, possibly, a change to an addition–elimination mechanism. The phenolysis reactions, in the presence of methyl substituents, can be described at fairly low phenol concentrations in terms of second-order rate coefficients, which fall off slightly in value as methyl groups are introduced. In contrast to methanolysis, the phenolysis shows a large decrease in rate on introduction of an electron-withdrawing chlorine substituent; this reduction is consistent with a retardation of the electrophilically assisted ionization mechanism proposed for phenolysis of the parent substrate.

“Amplifying” effect of hydrogen bonding on the correlation of frequencies of O–H stretching vibrations of phenols with Hammett substituent constants

The OH stretching frequencies measured for dilute solutions of various phenols in acetonitrile have been correlated with Hammett substitution constants.

26. Acylation. Part XIV. A comparison of the reactivities of acetyl and chloroacetyl chloride towards phenols in acetonitrile

The first page of this article is displayed as the abstract.