The Thermal Reversibility of the Michael Reaction: Iii. 1,5-Diketones and Adducts Bearing Acidic Groups

Abstract

In this paper a number of known chemical facts obtained by classical methods are correlated with the mass spectra of compounds thermally decomposed in the heated inlet of the mass spectrometer. Of the 31 substances examined, 24 are dioxo compounds. Among them are the few and only Michael adducts previously known to undergo thermal reversal. Both normal and abnormal types of retrogressior~ were found, but ketonic acids which could only regress normally, in a competing reaction, formed lactones by dehydration. A formally similar 6-hydroxyketone dissociated both ways in a comparable manner. Esters were more stable than cyano ketones under the conditions employed.

Studies on NaI/DMSO inducedretro-Michael addition (RMA) reactions on some 1,5-dicarbonyl compounds

“…9 Moreover, studies on the scope of RMA reactions, particularly those involving 1,5-ketodiesters and 1,5-diketones compounds are rare, though the reaction is known to take place for some aromatic 1,5diketones during mass spectral fragmentation. 10 Albrecht and coworkers 11 studied the RMA reaction of selected 1,5-diketones and showed that the reaction could be improved by using steam distillation in the presence of sodium hydroxide adsorbed on glass wool as catalyst. Li and Wang 12 studied steam-mediated RMA reaction for some 1,5-diketones present in steroid-like molecules.…”