Yu. P. Andreichikov

The lability of the halogen in 5(6)-bromo substituted benzimidazoles

The bromine atom is not labile either in 5-bromo-1-ethylbenzimidazole, its 6-nitro derivative, the isomeric 6-bromo-5-nitro compound, nor in the benzimidazolium salts derived therefrom. The similarly constituted 4-bromo-3-nitrotrimethylphenylammonium salt fairly readily exchanges its bromine atom for an arylamino group.

A new oxidative reaction in the 2-aminoimidazole series

Abstract2-Aminoimidazoles in liquid ammonia display the properties of polybasic NH acids, forming mono-, di-, and possibly trianions according to the conditions. The following methods have been developed for the generation of these N anions: the action of bases on 2-aminoimidazoles; debenzylation of their N-benzyl derivatives; and reductive fission of 2-azidoimidazoles by sodium in liquid ammonia. The polyanions have been shown to be oxidized by atmospheric oxygen to 2, 2′-azo- and 2-nitroimidazoles.

Synthesis of substituted 2- and 4-carboxypyrylium salts

Modified methods for the synthesis of substituted 2- and 4-carboxypyrylium perchlorates and the necessary diphenacylacetic acids are proposed.

Condensed heterocyclic systems with a quaternary nitrogen atom

Nitro and amino derivatives of pyrido[1,2-f]phenanthridinium perchlorate were synthesized by the Pschorr method and by photocyclodehydrogenation from N-(nitrophenyl)-or N-(aminophenyl)pyridinium perchlorates. The mechanism of the photoconversion was investigated.

Condensed heterocyclic systems with a quaternary nitrogen atom. III. Synthesis of benzimidazo[3,2-b]isoquinolinium perchlorates

Isochromylium cations containing easily detached groupings (NHCOR, NH2, OCH3) in the 3 position react readily with o-phenylenediamine. The reaction is accompanied by opening of the benzopyrylium ring and condensation of the resulting compound at one or two amino groups of o-phenylenediamine. Benzimidazo[3,2-b]isoquinolinium salts were synthesized alternatively by acylation of 2-(3,4-dimethoxybenzyl)benzimidazole. The tautomerism of the synthesized N-(2-aminoaryl)isoquinolinium perchlorates was investigated.

Properties of the amino group in N-(aminophenyl)pyridinium perchlorates

The pyridinium ring as a substituent in aniline is an electron acceptor, the effect of which is comparable to the effect of NO2 and N(CH3)2 groups. Correlation of the reactivities with the basicities of the amino groups is not observed in the investigated reactions of N-(aminophenyl)pyridinium perchlorates with some electrophilic reagents, inasmuch as steric factors apparently play a greater role.

Optical and photochemical properties of N-benzalaminophenylpyridinium perchlorates

The electronic spectra of a number of benzylidene derivatives of N-aminoarylpyridinium perchlorates are associated with absorption localized on the individual pyridinium and azomethine fragments and with intramolecular charge transfer (ICT) from the azomethine fragment to the pyridinium ring. The luminescence is associated with the latter process. The photochromism is due to proton transfer in the excited state of the azomethine fragment, which competes with ICT, and is also due to structural factors.

N-Aminoarylpyridinium perchlorates and their behavior in diazotization

N-Aminoarylpyridinium salts react with nitrosyl perchlorate to give diazonium dications, which undergo diazo coupling, exchange a diazo group, and are cyclized by the Pschorr method.