UV radiation and the reaction between ammonium and thiocyanate under prebiotic chemistry conditions

Abstract

The reaction between ammonium and thiocyanate under prebiotic chemistry conditions was studied using FT-IR spectroscopy. Ammonium thiocyanate (1.0 10-3 mol L-1) was dissolved in sodium chloride solution (28.57 g L-1) at two different pH values (5.30 and 7.20). FT-IR results showed that it was possible that some compound that resembles dithiooxamides was synthesized when samples of ammonium thiocyanate were exposed to UV radiation under a regular atmosphere, as UV radiation in the presence of oxygen leads to the formation of perchlorate ions (ClO4-) due to the presence of Cl- ions as well. After acid hydrolysis of the samples of ammonium thiocyanate irradiated under a nitrogen atmosphere, yellow and white compounds were obtained, which could not be identified. These results were different from those reported in the literature, where other authors found methionine. However, they used higher concentrations of ammonium thiocyanate and a different type of UV lamp. On the other hand, in the present study, a lower concentration of ammonium thiocyanate was used, which probably resembled more the concentration of ammonium thiocyanate of primitive earth.