Radical intermediates and stable products in acrolein pyrolysis

Acrolein is a commonly encountered pollutant of health concern, yet the processes that decompose acrolein are poorly understood. Frequently used in industrial synthesis, it is also a byproduct of combustion and other high temperature processes, especially those involving biological substances, e.g., forest fires, deep frying, or cigarette smoke. Despite the need for investigation of the chemical behavior of acrolein at high temperatures, little experimental work exists on decomposition of acrolein using apparatus capable of observing reactive species. Here, the pyrolysis of acrolein was studied at temperatures of up to 1700 K. We identified radicals and other unstable species produced in the early reaction stages, including vinyl radical, methyl radical, and methyl ketene. Detection of these reactive intermediates, and indirect evidence on the formation of others, reveals reaction pathways to stable species, including carbon monoxide, ethylene, and acetylene.