91232-52-9Relevant academic research and scientific papers
Pyrylium Compounds. XXII. 1H-N.M.R. and U.V. Spectroscopic Investigations on the Isomerization of Pseudobases of Unsymmetrically Substituted 2,4,6-Triarylpyrylium Salts
Fischer, Gerhard W.,Muegge, Clemens,Fink, Siegfried
, p. 647 - 656 (2007/10/02)
The kinetics and mechanism of the isomerization of the title compounds, the pentene-1,5-diones 2 and 3, were studied by 1H-n.m.r. and u.v. spectroscopy.The equilibrium constants measured vary little near 1, indicating the small influence of substituents on the equilibrium position.The mutual rearrangement 2(*)3 proved to be a base-catalyzed reaction which is characterized by a strictly linear Hammett correlation between lg k and (*)?p.The results obtained suggest resonance-stabilized anions of type 4 as intermediates. - Pseudobases of 3-alkyl-2,4,6-triarylsubstituted pyrylium salts do not undergo a reversible isomerization.
