Electrochemical amination of benzene in aqueous solutions of sulfuric acid and an organic solvent

Electrolysis of the Ti(IV)-NH2OH-C6H6 system in 11 M H2SO4 reveals that out of four organic solvents - methanol, formic acid, acetonitrile, and acetic acid - only the last two meet conditions imposed on solvents to be used in indirect cathodic amination of aromatic compounds. They improve the aromatic substrate solubility in the catholyte and affect the process mechanism, determining, together with other factors, the substitution's rate and selectivity

Electrochemical amination in the system Ti(IV)-NH 2OH-C 6H 6: The efficiency of the process in a sulfuric acid solution containing an organic solvent

Electrolysis of the system Ti(IV)-NH 2OH-C 6H 6 in an 11 M H 2SO 4 solution shows that using an organic solvent (acetic acid, acetonitrile) during cathodically initiated amination of aromatic substrates permits the production of aromatic amines with the overall yield by hydroxylamine reaching 91%. Due to a chain mechanism of radical substitution, the benzene amination in electrolytes containing 5 M CH 3COOH and 5.5 M CH 3CN terminates largely upon consuming 70-75 and 50-55% of the charge required theoretically for a one-electron process. The maximum efficiency of electrochemical amination is observed at low hydroxylamine conversions and the overall current efficiency for mono- and disubstituted products of the benzene amination may exceed in these conditions 750%

Electrochemical amination of unsaturated and aromatic compounds

The mechanism and synthetic perspectives of an indirect cathodic amination of unsaturated and aromatic substrates are considered. The influence of experimental conditions on the state and reactivity of the aminating reagent in solution is studied. The key role of the electrolyte acidity and redox properties of the reagents and intermediates in the obtained isomeric composition and the yield of the amination products is demonstrated

Electrochemical amination: Efficiency of a radical substitution

Electrochemical amination of benzene in sulfuric acid electrolytes is studied and experimental conditions for highly efficient synthesis of primary aromatic amino compounds are determined. In the electrolysis of Ti(IV)-NH 2OH-C 6H 6 in 11 M H 2SO 4 solutions containing acetic acid or acetonitrile as organic solvents, aniline and isomeric phenylenediamines are obtained with the total yields by hydroxylamine of 95.6 and 99.6%, respectively. A monoamino compound is the main product of radical substitution in acidic organo-aqueous media. It is found that the use of acetonitrile in electrochemical process is limited to certain sulfuric acid concentrations and temperatures

Efficiency of electrochemical amination of anisole in aqueous-organic solutions of 4 M H 2SO 4

Cathodically initiated amination of anisole has been performed with the Ti(IV)-NH 2OH system in aqueous solutions of 4 M H2SO4 containing high concentration of acetic acid or acetonitrile. In electrolyses performed to reach full conversion of hydroxylamine, the isomeric anisidines obtained (2 para/ortho ∼ 3.9) with total yields referred to the current and amino radical source exceeded 80%. © Pleiades Publishing, Ltd., 2012

Electrochemical amination. Dilute aqueous organic solutions of sulfuric acid

The electrochemical process of anisole amination is studied in 1.5-9 M H2SO4 solutions containing acetonitrile or acetic acid. It is shown that the synthesis of aromatic monoamino compounds is better performed in moderately acidic media with high concentrations of organic solvents. Due to the chain mechanism of the electrochemical process, the current efficiency of amines can exceed 150% under these conditions. © 2009 Pleiades Publishing, Ltd

Electrochemical amination. synthesis of aniline in aqueous–acetonitrile solutions of sulfuric acid

© 2015, Pleiades Publishing, Ltd. The process of indirect cathodic amination of benzene is studied in aqueous media containing 4-10 M H2SO4 and, accordingly, 13.8–7.1 M CH3CN. At 50°C, electrolysis in the system of Ti(IV)–NH2OH–C6H6 results in formation of aniline and also small amounts of isomeric phenylenediamines and diphenyl. The current efficiency of aniline is maximum in the catholyte containing 8 M H2SO4 and 9.4 M CH3CN. Under these conditions, full conversion of hydroxylamine is observed; the 80% current efficiency of aniline corresponds to the efficiency of the amino radical source and its mass fraction among the products of electrolysis exceeds 97%

Electrochemical amination. Functionalization of anisole in solutions of 4.0-6.0 M H 2SO 4 and acetic acid

The electrochemical amination of anisole in 4.0-6.0 M H 2SO 4 solutions containing CH 3COOH and small amounts of water is studied with the use of the Ti(IV)/Ti(III)-NH 2OH system. Under these conditions, the products of radical substitution are para- and ortho-anisidines. Their total current efficiency and yield by hydroxylamine are 82.0% at a complete conversion of the source of amine radicals. Owing to the chain mechanism, the electrochemical process is terminated upon consumption of no more than 0.5 electrons per NH 2OH molecule. At a small charge passed through the electrolyte, the anisidines current efficiency can exceed 380%. © 2011 Pleiades Publishing, Ltd

Electrosynthesis of anisidines in aqueous sulfuric and acetic acids

The influence of the concentrations of acetic and sulfuric acids on the efficiency of anisole amination by means of hydroxylamine and Ti(IV)/Ti(III) mediator was studied. Ortho- and para-anisidines were obtained with the total yields of about 79% by current and hydroxylamine. © 2009 Pleiades Publishing, Ltd

Electrochemical behavior of Ti(IV)/Ti(III) redox couple on dropping mercury electrode in sulfuric acid aqueous and aqueous-organic media

The processes of electrochemical reduction of Ti(IV) and oxidation of Ti(III) in aqueous solutions of H2SO4 not containing and containing AcOH or MeCN are studied by the methods of classical and commutation polarography. It is shown that in the absence of organic solvents the heterogenous electron transfer is irreversible in the media with the sulfuric acid concentration up to 9 M, while in aqueous-organic solution the same occurs at the concentration up to 7 M. Organic solvents are involved into the process of complex formation and like H2SO4, influence the step of heterogenous electron transfer; this effects weakens with the increase in the concentration of sulfuric acid. © 2009 Pleiades Publishing, Ltd