Anodic Synthesis Research Articles

Anodic synthesis of benzaldehydes—I. Voltammetry of the anodic oxidation of toluenes in non-aqueous solutions

The electrode kinetic investigation of the three consecutive steps of anodic toluene oxidation in methanol, namely the two-electron oxidation of toluene to benzylalcohol methylether, the two-electron oxidation of benzylmethylether to benzaldehyde dimethylacetal and the multielectron oxidation of benzaldehyde dimethylacetal to a mixture of unknown products was performed, using voltammetry at rotating and stationary disc electrodes and the rotating ring-disc electrodes in methanol, ethanol and acetonitrile as solvents. Investigated were toluene, benzylalcohol and benzaldehyde as references and para-substituted toluenes, benzylalcohols and benzaldehydes. Substituents with (+)I-effect activate the toleune towards anodic attack, substituents with (−)I-effect deactivate the aromatic system. A detailed electrode kinetic investigation is possible for p-methoxytoluene, the respective benzylalcohol and benzaldehyde. The current-voltage curve is almost exclusively mass transfer controlled. The chemical reaction following the first charge transfer is a first order reaction and is likely to be the proton dissociation of the toluene radical cation. It is heterogeneously catalysed as the choice of the anode material influences the half wave potential. In acetonitrile, as a more acidic solvent, dimerization seems to become important. A full description of the current-voltage curves by appropriate modelling is impossible as experimental inaccuracies do not allow for proper determination of the kinetic parameters. The proton dissociation rate of p-methoxytoluene radical cations can be estimated to be faster than 10 5s −1.

Anodic synthesis of benzaldehydes—II. Optimization of the direct anodic oxidation of toluenes in methanol and ethanol

The direct anodic oxidation of 3,4,5-trimethoxytoluene, p-methoxytoluene, toluene and p-chlorotoluene had been investigated by preparative electrolyses in dry methanol and ethanol solution with NaClO 4, NaBF 4 and Et 4N · BF 4 as a supporting electrolyte at graphite anodes in batch experiments. 3,4,5-trimethoxytoluene oxidation yields almost no benzaldehyde dimethylacetal but anodic oligo- and polymers. If oxidized, however, in the presence of 0.1 molar sodium methoxylate, the yield and selectivity of the benzaldehyde synthesis approaches 100%. With the three other toluenes, benzylmethyl (or ethyl) ethers and benzaldehyde dimethyl (or diethyl) acetals are obtained due to consecutive reaction steps. The acetals are further oxidized to a number of compounds among which benzoic acid ortho-esters and esters had been identified. The direct anodic oxidation of the three toluenes is almost always accompanied by anodic polymerization, so that material yields of less than 100% and selectivities between 0 and, at best, 70% are obtained for the anodic synthesis of benzaldehyde dialkylacetals at close to 100% conversion of the toluenes. The amount of benzylmethyl ethers produced as by-product is always low and approaches zero if the toluene conversion is almost complete. The observed polymerization reaction which in unfavourable cases consumes almost all converted toluene is contrary to predictions and model calculations which are based on voltametric data. Modelling of the anodic conversion of toluenes by using voltammetric data leads only to a qualitative agreement between experiment and model-predictions and optimization has to be performed by trial and error. However, optimal selectivities do not surmont 70 to 75% for p-methoxytoluene and p-chlorotoluene and only 30% for toluene.

Anodic synthesis and characterization of millimeter crystals of Ba 0.6K 0.4BiO 3

Anodic electrosynthesis of Ba 0.6K 0.4BiO 3 leads to millimeter-sized crystals of this cubic superconductor with transition temperatures of 30.5 K. Clusters of these lustrous blue-black crystals are grown on gold anodes in graphite crucibles which conveniently serve as the cathode. Details of the electrochemical procedure utilizing a hydroxide melt are given, along with the characterization of the superconductive transition by microwave absorption and magnetic measurements, and confirmation of the composition and structure with X-ray diffraction. The availability of crystals with cubic facets of up to 10 mm 2 has facilitated characterization and application of this material.

Synthesis of 12-oxophytodienoic acid (12-oxoPDA) and the compounds of its enzymic degradation cascade in plants, OPC-8:0, -6:0, -4:0 and -2:0 (epi-jasmonic acid), as their methyl esters

The synthesis of 12-Oxophytodienoic acid, and the compounds of its enzymic degradation sequence, OPC-8:0, -6:0, -4:0 and -2:0, important plant metabolites derived from linolenic acid, is reported. The syntheses use the known cyclopent-3-ene-1,2-diacetic acid as an early intermediate, and this is derived from the Cope rearrangement of 5-vinyltrinorborn-2-ene via bicyclo[4.3.0]nona-3,7-diene. lodolactonisation and tributyltin hydride reduction provides the key intermediate (3-oxo-2-oxabicyclo[3.3.0]octan-6-yl)acetic acid for the OPC series, whilst phenylselenolactonisation and elimination provides the necessary unsaturated lactone (7-oxo-8-oxabicyclo[3.3.0]oct-2-en-4-yl)acetic acid for 12-oxoPDA. Members of the OPC-series were made by chain extending the saturated oxabicyclooctane acid: that for the OPC-4:0 involved double Arndt–Eistert reaction, whilst the intermediates for OPC-6:0 and -8:0 were made by Kolbe anodic crossed coupling. The lactones were then converted via their lactols, Wittig reaction, esterification and oxidation, into the compounds of the OPC ester series, including OPC-2:0 (methyl epi-jasmonate).The unsaturated lactone 8-(7-oxo-8-oxabicyclo[3.3.0]oct-2-en-4-yl)octanoic acid required for 12-oxoPDA synthesis could also be prepared by anodic synthesis either from (7-oxo-8-oxabicyclo[3.3.0]oct-2-en-4-yl)acetic acid, or from its 2-phenylseleno-2, 3-dihydro precursor as elimination occurred concomitantly during the reaction. Since yields were low, the unsaturated acid lactone was converted into its lactol and the (Z)-pent-2-enyl side-chain was inserted first. After TBDMS blocking of the cyclopentene hydroxy group, the side-chain was elaborated to give 5-(pent-2-enyl)cyclopent-2-enylacetaldehyde and chain extension carried out by a Grignard-demesylation procedure. Sequential desilylation and depyranylation, followed by oxidation of the diol, gave 12-oxoPDA, isolated as its methyl ester.

Anodic synthesis and molecular structure of dodecaethylhexaamidobisphosphonium diperchlorate

The electrochemical oxidation of hexaethyl triamidophosphite in the absence of nucleophiles specially introduced into the electrolyte was studied by anodic voltamperometry and preparative electrolysis. The reversible one-electron oxidation of the triamidophosphite molecule gives an unstable radical-cation, which reacts with a molecule of the starting compound to give a dimeric radical-cation, whose subsequent oxidation leads to dodecaethylhexaamidobisphosphonium diperchlorate. This product is the first example of an acyclic, doubly charged bisphosphonium cation with a\(\mathop P\limits^ + - \mathop P\limits^ + \). The crystal structure of this compound was obtained by x-ray diffraction structure analysis.

Electrochemical synthesis of heterocyclic compounds—XX. Anodic synthesis of N-heterocycles with organic mediators

Anodic oxidations of a azomethine derivatives ( 1–4) mediated by cation radicals (I + or II +) were performed in acetonitriletetraethylammonium perchlorate electrolyte solution by controlled potential electrolysis. As a result of anodic oxidation corresponding N-heterocycles ( 1a–4a) were isolated in good yields ranging from 50–81%.

Properties and electrochemical behavior of a new electroactive polymer: Polydibenzofuran

The anodic synthesis, some properties and the electrochemical behavior of polydibenzofurans are presented. These new polymers can be reversibly p- or n-doped under precise experimental conditions, without alteration of the material.

ChemInform Abstract: Anodic Synthesis of Butenolides from β‐Ethylenic Esters. Double Cyclization in the Presence of Olefins.

ChemInform Abstract: Anodic Synthesis of Butenolides from β‐Ethylenic Esters. Double Cyclization in the Presence of Olefins.

Electrochemical synthesis of heterocyclic compoudsn—XIX. Anodic synthesis of bichromones by oxidation of enaminones

Anodic oxidation of enaminones ( 1– 4), prepared from o-hydroxyacetylarenes and N,N-dimethylformamaide dimethylacetal, were performed in acetonitrile—tetraethylamonium perchlorate electrolyte solution by controlled potential electrolysis. As a result of anodic oxidation corresponding bichromones ( 1a– 4a) were isolated in good yields ranging from 42 to 68%. On the bases of the electroanalytical and preparative results the mechanism of the reaction—including electron transfer, cyclization of radical cation, dimerization and proton and dimethylamine elimination—was discussed.

Anodic synthesis of butenolides from β-ethylenic esters double cyclization in the presence of olefins

Anodic oxidation of β-ethylenic esters yields butenolides 2 . In the presence of 1-phenyl-1-propene or α,β-disubstituted indenones a double cyclization takes place to yield more complex butenolides

ChemInform Abstract: Anodic Synthesis of Trifluorophosphoranes.

AbstractThe title compounds (III) are obtained by anodic oxidation of the secondary phosphines (I) in the presence of the ammonium fluoride (II).

Anodic synthesis of sulfur‐bridged polyaniline coatings onto Fe sheets

AbstractSulfur‐bridged polyaniline coatings are obtained onto Fe anodes by electrolyzing a basic solution of one aniline and ammonium sulfide. Their sulfur content ranges from 7% to 17%, depending on the substituents on aniline. Variously substituted anilines may be polymerized in this way and coating pollution by azobenzene formed in a side reaction is almost completely avoided. Sulfur probably enters the polymer chains through a free radical mechanism. HS• intermediates being formed by both homogeneous and anodic oxidation of HS− anions. Coatings from N‐allylaniline, being thermally curable, show satisfactory physical properties.

Electrochemical synthesis of heterocyclic compounds—XIII. (1) Anodic synthesis of 1, 3-imidazoles and 1, 3-oxazoles derivatives

Anodic oxidation of a series of structurally different Schiff bases ( 1a – 15a ), prepared from o-phenylendiamine, o-aminophenol, 3-amino-4-hydroxycoumarine or 3,4-diaminocoumarine and corresponding aromatic aldehyde, were performed in acetonitrile-tetraethylammonium perchlorate electrolyte solution at platinum using controlled potentials. As a result of two-electron oxidative cyclodehydrogenations several 1,3-oxazoles derivatives (1b–10b) and 1,3-imidazoles derivatives (11b–15b) were prepared in the yields ranging from 60 to 90%. A mechanism rationalizing the formation of 2-anisylbenzimidazole, 11b , and 2-anisylbenzoxazole, 3b , has been studied by lsv, cpsv, rde, coulommetry and preparative scale electrolysis.

Electrochemical Synthesis of Heterocyclic Compounds. XV. Anodic Synthesis of s-Triazolo[4,3-a]pyridine Derivatives.

Electrochemical Synthesis of Heterocyclic Compounds. XV. Anodic Synthesis of s-Triazolo[4,3-a]pyridine Derivatives.

The Reactivity of Primary Free Radicals and Radical Ions, Mass Transfer, and Electrosorption—The Fundamental Factors for Selectivity in Electrochemical Syntheses of Organic Compounds

AbstractIn many cases the electrolytic synthesis of organic compounds is rather unselective. This is because the primary radical ions and/or radicals are very often so reactive that they are able to react competitively with several of the different species present in the electrolyte. The aim is to increase the selectivity by rationally altering the process parameters; this demands a knowledge, inter alia, of electrosorption effects and of the relationships between mass transfer and chemical reaction, at or in front of the electrodes (in the so‐called reaction layer). Four examples will be used to illustrate this theme: The anodic synthesis of triarylsulfonium salts, The addition of anodically generated N3‐radicals to olefins, producing “monomeric” 1,2‐diazides and “dimeric” 1,4‐diazides, The cathodic synthesis of optically active 1‐(2‐pyridyl)ethanol, The synthesis of 1,2‐ and 1,4‐diol ethers by anodic oxidation of vinyl compounds in alcoholic solutions.

Anodic synthesis of polyaniline coatings onto fe sheets

AbstractAniline Black coatings were obtained on Fe anodes by electrolyzing a basic solution of aniline in a water—methanol medium. Allylamine (an inhibitor of Fe corrosion), although not essential to the process, imparts better efficiency to it. The deposited polymers contain 15–20% azobenzene and exhibit semiconductor properties. The three nitroaniline isomers need a more efficient corrosion‐inhibition system. They may be polymerized to adherent films in the presence of both allylamine and K2CrO4.

ChemInform Abstract: ANODIC SYNTHESIS OF FLUORINATED QUINONES

Chemischer InformationsdienstVolume 10, Issue 24 Isocyclic Compounds ChemInform Abstract: ANODIC SYNTHESIS OF FLUORINATED QUINONES Z. BLUM, Z. BLUMSearch for more papers by this authorK. NYBERG, K. NYBERGSearch for more papers by this author Z. BLUM, Z. BLUMSearch for more papers by this authorK. NYBERG, K. NYBERGSearch for more papers by this author First published: June 12, 1979 https://doi.org/10.1002/chin.197924196Read 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. Volume10, Issue24June 12, 1979 RelatedInformation

Anodic Synthesis of Fluorinated Quinones.

Anodic Synthesis of Fluorinated Quinones.

Electrochemical Synthesis of Heterocyclic Compounds; VII1. Anodic Synthesis of 1,3-Thiazole Derivatives

Electrochemical Synthesis of Heterocyclic Compounds; VII¹. Anodic Synthesis of 1,3-Thiazole Derivatives

Anodic Synthesis of Organic Carbonates

Carbonic acid esters (carbonates) are produced by electrolysis of carbon monoxide and the corresponding alcohol in the presence of a halide electrolyte. The halide electrolyte plays a catalytic role in carbonate formation. The efficiency for the process depends, among other variables, on the starting alcohol. Both mono and 1,2‐dihydric aliphatic alcohols form carbonates in high yields. Under our electrolytic conditions, without optimization, dimethyl carbonate from methanol and ethylene carbonate from ethylene glycol were formed with 80 and 45% current efficiencies, respectively. One mole of hydrogen is liberated per mole of carbonate. Organic carbonates represent a class of important industrial solvents. They are commercially produced via employment of phosgene; is formed as a by‐product. The electrochemical process obviates the use of phosgene and eliminates the hydrochloric acid disposal problem.