Hemiaminal route for the formation of interstellar glycine: a computational study

Calculations related to two simple two-step paths (path-I: H2C=O+NH3 -> alpha -hydroxy amine<mml:mspace width="0.25em"></mml:mspace>-> +CO</mml:mover><mml:mspace width="0.25em"></mml:mspace>glycine, path-II: <mml:mspace width="0.25em"></mml:mspace>H2C=NH+H2O -> alpha -hydroxy amine<mml:mspace width="0.25em"></mml:mspace>-> +CO</mml:mover><mml:mspace width="0.25em"></mml:mspace>glycine) for the formation of glycine have been discussed. Calculations show that at interstellar conditions these two paths are feasible only in hot cores, not in the cold interstellar clouds (cold core formation is possible only if CH2 = NH, H2O (excess) and CO of path-II, react in a concerted manner). For the laboratory synthesis of glycine, the possibility suggested is via path-I and the reaction being carried out as controlled temperature one-pot synthesis. This study can also be extended to other alpha -amino acids and possibly enantiomeric excess can be expected. We think this work will not only be able to enrich our future understanding about the formation of amino acids in interstellar medium but also be able to suggest alternative paths for laboratory synthesis of amino acids using either Strecker's or Miller's ingredients.<fig id="Figa" position="anchor"><caption xml:lang="en">Using computational calculations, two different reaction paths which go through a hemiaminal (alpha -hydroxyamine) intermediate have been proposed. It has been proposed that the reaction H2C=O+NH3 -> alpha -hydroxyamine<mml:mspace width="0.25em"></mml:mspace>-> +CO</mml:mover><mml:mspace width="0.25em"></mml:mspace>glycine, is a thermodynamically favorable reaction path in the laboratory conditions, if carried out as a controlled temperature one-pot synthesis. On the hand, it has been argued that the reaction<mml:mspace width="0.25em"></mml:mspace>H2C=NH+H2O -> alpha <mml:mo>-hydroxy amine<mml:mspace width="0.25em"></mml:mspace><mml:mover accent="false"><mml:mo>-> <mml:mo>+CO</mml:mover><mml:mspace width="0.25em"></mml:mspace>glycine is a feasible reaction path in the interstellar conditions, if it proceeds not via the hemiaminal route, rather in a concerted reaction path.</caption><graphic position="anchor" specific-use="HTML" mime-subtype="PNG" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="894_2019_4224_Figa_HTML.png" id="MO1"></graphic