THE THERMAL REVERSIBILITY OF THE MICHAEL REACTION: I. NITRILES

Abstract

Michael adducts of nitriles and α,β-unsaturated ketones have been found generally to undergo two or more kinds of thermal reversibility upon being heated to moderate temperatures. When the products are those from which the adduct was prepared, the dissociation is termed "normal," whereas the "abnormal" route gives an α,β-unsaturated nitrile and a methyl ketone. The scope and generality of the reversibility are described in three papers. The first deals with 31 ketonic nitriles, the second with nitroketones, and the last with diketones and acidic derivatives.Allowing the materials to decompose thermally in the heated inlet of a mass spectrometer permits a direct study of thermal reaction mixtures and it affords data the interpretation of which gives an indication of the products present, many of which may not have been previously expected. Identification of products is confirmed by comparison of the mass spectra with those of reference compounds. Under favorable conditions, such products can be isolated from independent decomposition reactions and their identities further confirmed by classical chemical methods. Both operations have been done often enough to show the general application of the mass spectrometer for this purpose. Thus laborious laboratory separations may be avoided. In two instances the four major products from both paths were isolated, identified, and quantitatively determined.