A Computational Study of a Prebiotic Synthesis of D-Riboflavin (Vitamin B2)

Abstract

Ab initio applied computing is used to determine the viability of a plausible mechanism for the formation of riboflavin from planetary and interstellar gases that contain the necessary essential elements. The immutable laws of chemical thermodynamics and kinetics enable the intermediates in the synthesis to be characterized and the activation energies to be established. The gases propyne, cyanogen, carbon monoxide, and hydrogen are invoked in a synthesis of the isoalloxazine precursor of the vitamin riboflavin (Vitamin B2), whilst the additional presence of hydrogen cyanide enables the surface-catalyzed, photochemically activated synthesis of a D-ribitylamine requiring the magnesium metalloporphyrin catalyst. These two molecules then bond in a Sn2 reaction to form the final vitamin structure. The reactions have been shown to be feasible from the overall enthalpy changes in the ZKE approximation at the HF and MP2 /6-31G* level and with acceptable activation energies.