Quantum Tunneling Mediated Low-Temperature Synthesis of Interstellar Hemiacetals.

Sugars and sugar-related molecules are ubiquitous in carbonaceous meteorites and in star-forming regions, but the underlying mechanisms of their formation have remained largely elusive. Herein, we report an unconventional synthesis of the hemiacetal, ( R / S )-1-methoxyethanol (CH 3 OCH(OH)CH 3 ), through quantum tunneling mediated reactions in low-temperature interstellar model ices composed of acetaldehyde (CH 3 CHO) and methanol (CH 3 OH). The detection of racemic 1-methoxyethanol through a bottom-up synthesis from simple, abundant precursor molecules within interstellar ices represents a vital starting point to the formation of complex interstellar hemiacetals. Once synthesized, hemiacetals may act as possible precursors to interstellar sugars and sugar-related molecules in deep space.