Acetoin, CH 3 C(O)CH(OH)CH 3 , is an additive used in foods and cigarettes as well as a common component of biomass pyrolysate during the production of biofuels, yet little is known about its thermal decomposition mechanism. In order to identify thermal decomposition products of acetoin, a gas-phase mixture of approximately 0.3% acetoin in argon was subject to pyrolysis in a resistively heated SiC microtubular reactor at 1100-1500 K. Matrix-isolation FTIR spectroscopy was used to identify pyrolysis products. Many products were observed in analysis of the spectra, including acetylene, propyne, ethylene, and vinyl alcohol. These results provide clues to the overall mechanism of thermal decomposition and are important for predicting emissions from many industrial and residential processes.

The 1-butyn-3-yl radical (C 4 H 5 ) is thought to play a role in the formation of hydrocarbons in the interstellar medium and planetary atmospheres, but it is not well characterized. In this study, the 1-butyn-3-yl radical was formed by the pyrolysis of gas-phase 3-bromo-1-butyne at temperatures of 800-1200 K. Nascent radicals were isolated in an argon marix, followed by FTIR spectroscopy. Vibrational bands in the experimental spectra were matched to frequencies predicted by Gaussian 09. Pyrolysis of 3-methyl-1-butyne was also investigated as a possible pyrolytic precursor to the 1-butyn-3-yl radical under similar conditions. Evidence of 1-butyn-3-yl formation was observed, but other radicals may have formed as well.