FTIR spectroscopic investigation of matrix-isolated isomerization and decomposition products of ionized acetone: generation and characterization of 1-propen-2-ol

Abstract

An electron bombardment – matrix isolation apparatus was used to generate and isolate products from acetone isomerization and decomposition for infrared spectroscopic examination. Bombardment of a dilute acetone/argon gas mixture (1:400) above a 12 K matrix isolation substrate leads to the direct observation of neutral fragmentation and isomerization products. A major product is 1-propen-2-ol, the enolic tautomer of acetone, whose IR absorption spectrum, and that of its perdeutero analog, are interpreted with the aid of ab initio computations. The observation of matrix-isolated decomposition products of acetone such as acetyl radicals, ketene, methane, and CH3• is interpreted in terms of ion and neutral decomposition processes occurring in the gas phase above the matrix surface and during matrix condensation. The detection of matrix-isolated 1-propen-2-ol is consistent with a process involving acetone ionization, isomerization, neutralization, and stabilization, an approach that may have general utility in the generation of other thermodynamically unfavourable neutral isomers of organic molecules. Keywords: enol, isomerization, acetone, infrared, ionization, 1-propen-2-ol.