N. Kleimeier, A. Turner, R. Fortenberry
May 26, 2020
Citations
1
Influential Citations
8
Citations
Journal
Chemphyschem : a European journal of chemical physics and physical chemistry
Abstract
Acetaldehyde (CH 3 CHO) is ubiquitous throughout the interstellar medium and has been observed in cold molecular clouds, star forming regions, and in meteorites such as Murchison. As the simplest methyl-bearing aldehyde, acetaldehyde constitutes a critical precursor to prebiotic molecules such as the sugar deoxyribose and amino acids via the Strecker synthesis. In this study, we reveal the first laboratory detection of 2,3-butanedione (diacetyl, CH 3 COCOCH 3 )-a butter and popcorn flavorant-synthesized within acetaldehyde-based interstellar analog ices exposed to ionizing radiation at 5 K. Detailed isotopic substitution experiments combined with tunable vacuum ultraviolet (VUV) photoionization of the subliming molecules expose that 2,3-butanedione is formed predominantly via the barrier-less radical-radical reaction of two acetyl radicals (CH 3 ĊO). These processes are of fundamental importance for a detailed understanding of how complex organic molecules (COMs) are synthesized in deep space thus constraining the molecular structures and complexity of molecules forming in extraterrestrial ices containing acetaldehyde through a vigorous galactic cosmic ray driven non-equilibrium chemistry.