SELECTIVE THERMOLYSIS OF THE ENOL FORMS OF ACETOACETATES DURING GAS-CHROMATOGRAPHY, REVEALED BY COMBINED MATRIX-ISOLATION FOURIER-TRANSFORMINFRARED AND MASS-SPECTROMETRY

The thermal decompositions of methyl and ethyl acetoacetates have been observed by combined gas chromatography (GC)-mass spectrometry-matrix -isolation Fourier transform infrared spectrometry. Under the conditio ns employed, keto and enol forms could be separated by GC and, by care ful control of interface temperatures, the thermolysis of the individu al components could be studied. Each enol acetoacetate form was almost completely converted to a keto-ketene and an alcohol. The keto-acetoa cetate forms were only partially decomposed, with reaction products id entical to those of the enol forms, indicating that the preferred mech anism of thermal degradation is via the enol-acetoacetate form.