Formamide Dehydration and Condensation on Acidic Montmorillonite: Mechanistic Insights from Ab-Initio Periodic Simulations

Formamide (NH2CHO) is a molecule of extraordinary relevance as prebiotic precursor of many biological building blocks. Its dehydration reaction, which could take place during the Archean Era, leads to the production of HCN, the fundamental brick of DNA/RNA nitrogenous bases. Mineral surfaces could have played a crucial role in activating biological processes which in gas phase would have too high activation barriers to occur, thus allowing the event cascade, which finally led to the formation of biological macromolecules. In the present work we studied the dehydration process of formamide (NH2CHO → HCN + H2O) as catalyzed by a surface of acid montmorillonite. In this surface, a silicon atom has been substituted by an aluminium one, thus generating a negative charge that is compensated by an acidic proton on the top of the surface. This proton should, in principle, help the formamide dehydration. However, our results indicate that this particular acidic surface does not exert an efficient catalytic behavior in the decomposition of formamide.