Microwave detection of interstellar vinyl alcohol, CH2=CHOH

Vinyl alcohol (CH2 = CHOH) has been detected in emission toward Sagittarius B2N by means of its millimeterwave rotational transitions. The simplest en ol, vinyl alcohol is an important intermediate in many organic chemistry re actions. All three stable isomers of the C2H4O family, vinyl alcohol, ethyl ene oxide (c-C2H4O), and acetaldehyde (CH3-CHO) have now been identified in the interstellar medium, as have the three members of the C2H4O isomeric g roup (Hollis, Lovas, and Jewell). These complex species cannot be produced in detected amounts by quiescent gas-phase chemistry models, and grain proc esses have long been envisioned. Our analysis of the abundances of the six species suggests that evaporation from grains of copious amounts of less co mplex species such as CH3OH and H2CO, followed by gas-phase reactions among the evaporated species, explain the high abundance of four of the species, while isomerization (on grains) of the less stable glycol aldehyde and vin yl alcohol species accounts for their lower abundances. The role of catalys is on grains remains unclear.