# How Does Adenine Form from Hydrogen Cyanide?

## TL;DR

This paper explores how adenine, a key building block of life, can form from hydrogen cyanide through complex chemical reactions.

## Contribution

The study reveals new reaction steps and confirms the role of DAMN as a necessary intermediate in adenine formation.

## Key findings

- A complex, nonequilibrium interplay between four base-catalyzed pathways to adenine was identified.
- Polyimine was found to act as an oxidizing agent in one of the newly discovered reaction steps.
- Diaminomaleonitrile (DAMN) is confirmed as a necessary intermediate in adenine formation.

## Abstract

The abiotic formation of adenine from hydrogen cyanide
(HCN) has
long been suspected to be a key step in the origin of life. However,
the inherent complexity of HCN’s self-reaction chemistry has
challenged researchers for decades, obscuring the detailed mechanistic
pathway to adenine. In this study, we employ quantum chemistry and
microkinetic modeling to predict and compare four interwoven base-catalyzed
pathways to adenine in liquid HCN. Our analysis incorporates both
previously proposed aminomalononitrile (AMN) and diaminomaleonitrile
(DAMN) intermediates and reveals previously unknown reaction steps,
including one in which polyimine can serve as an oxidizing agent.
Our modeling offers compelling evidence of a complex, nonequilibrium
interplay between these pathways and confirms DAMN as a necessary
intermediate. This work establishes a foundational reference for the
exploration of abiotic nucleobase formation and highlights how rigorous
testing of origin-of-life chemistry pushes the boundaries of state-of-the-art
computational chemistry.