SPACE SIMULATIONS. “Earlier experiments of Bernstein et al. were conducted with a larger temperature range (12–300 K), and in addition to the above-mentioned products, they discovered hexamethylenetetramine (C6H12N4), ethers, alcohols, compounds related to polyoxymethylene, ketones and amides in their samples. Their subsequent experiments showed the formation of aroma-bearing ketones and carbolylic acid functional groups.”
https://royalsocietypublishing.org/doi/10.1098/rsif.2016.0459