Ethylene glycol [IUPAC name 1,2-ethanediol] is the simplest dialcohol (or diol). A (toxic) liquid under standard pressure from 197 °C down to −12 °C, its mixture (70–30 %) with water remains liquid down to −51 °C, which explains its use as antifreeze. It is currently produced by reaction of ethylene oxide (oxirane, C2H4O) with water. Ethylene glycol has been found in the interstellar medium toward the galactic center and in comet C/1995 O1 (Hale-Bopp).
Detection of ethylene glycol in interstellar matter was rather difficult; it was performed for the first time by Hollis et al. (2002) toward the galactic center. This contrasts with the relative strength of the lines in comet C/1995 O1 (Hale-Bopp), where this molecule was identified in archive spectra as soon as the line frequencies were available (Crovisier et al. 2004). Several conformers of ethylene glycol exist (Hollis et al. 2002), and the astronomical detections prior...