Radiolytic Synthesis of Cyanogen Chloride, Cyanamide and Simple Sugar Precursors

Chemical evolution, from simple molecules to complex systems, is fundamental to modern origins of life research, and complex reaction networks are often supposed to have operated on the early Earth. Herein, a variety of compounds useful particularly for RNA synthesis - namely, cyanogen chloride, cyanamide, and nitrile precursors to simple sugars - are produced in short order by a chemical reaction network starting from hydrogen cyanide and driven by gamma radiolysis. The radiolytic yield of cyanamide was found to be proportional to the concentration of chloride, an often overlooked spectator anion. Aqueous irradiation of hydrogen cyanide in the presence of sodium chloride also affords cyanogen chloride, a possible intermediate in the radiolytic synthesis of cyanamide. Meanwhile, the synthesis of simple sugar precursors is proposed to proceed through a Kiliani-Fischer homologation mechanism made possible by the reducing power of the solvated electron and hydrogen atom. Such a reaction network has the potential to serve as a model for better understanding and engineering chemical evolution of complex mixtures in the laboratory that could have happened on the early Earth.