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 retrogression were found, but ketonic acids which could only regress normally, in a competing reaction, formed lactones by dehydration. A formally similar β-hydroxyketone dissociated both ways in a comparable manner. Esters were more stable than cyano ketones under the conditions employed.