Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Systems with Thirteen Conjugated Atoms

The triaryl compounds 290 (R = Ar) are prepared by condensation of 2-aminophenol with triarylpyrylium salts followed by treatment with alkali. The triphenyl betaine (290 R = Ph) is obtained as a purple solid, mp 165 C (decomp), which shows large thermo/solvatochromic effects. Oxidation of the betaine 290 (R = Ph) with hydrogen peroxide gives the triphenyl-pyridinium-3-olate 291 (R = Ph) (see Section III,A,2) and the pyrrole 292 (R = Ph). The mechanism of this unusual reaction has not yet been Established. [Pg.53]

Examples of these betaines (293) are the bridged heterocycles 295, which have been made by condensation of l,2,4-triazin-5-one derivatives 294 with aldehydes or ketones.2-2is yj g molecular structure of compound 295 (R = H, R2 = R = Me, R = SMe) has been determined by X-ray crystallography. Acetylation gives derivatives 295 (R = Ac) which with methyl iodide give the deep red salts 296 in high yield. [Pg.53]

Doleschall and K. Lempert, Acta Chim. Acad. Sci. Hung. 77, 345 (1973). [Pg.53]

The betaines 297 are easily prepared from a pyrylium salt and the appropriate 4-aminophenol followed by deprotonation. Typically, 2,4,6-triphenyl-pyridinium iodide and 4-aminophenol give the blue-black betaine (297 R = R = Ph, R = H) which also occurs as a red hexahydrate. With methyl iodide this compound gives 7V-(p-methoxyphenyl)-2,4,6-triphenyl-pyridinium iodide. 10,221 [Pg.54]


See other pages where Systems with Thirteen Conjugated Atoms is mentioned: [Pg.52]    [Pg.52]    [Pg.52]    [Pg.52]   


SEARCH



Atomic systems

Conjugate system

Conjugated atom

Conjugated system conjugation)

Conjugated systems

© 2024 chempedia.info