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 CH 3 • 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.