# Fragmentation Dynamics of Benzoyl Peroxide: Insights from Rotational Spectroscopy

## TL;DR

This study uses rotational spectroscopy to understand the structure and breakdown of benzoyl peroxide, offering insights into its stability and decomposition.

## Contribution

First gas-phase rotational spectroscopy characterization of benzoyl peroxide and identification of its decomposition products.

## Key findings

- BPO has a C2-symmetric structure with quasi-perpendicular aromatic rings.
- A stabilizing n→π* interaction between carbonyl groups contributes to BPO's thermal resilience.
- Photofragmentation products include benzoic acid, benzyne, benzaldehyde, and benzophenone.

## Abstract

Benzoyl peroxide
(BPO) represents a structurally simple
yet hazardous
organic peroxide with widespread applications across industrial and
pharmaceutical domains. Despite its extensive use, detailed molecular-level
understanding of its thermal instability remains limited. Here, we
present the first rotational spectroscopy characterization of isolated
BPO in the gas phase, enabled by laser ablation and supersonic jet
expansion techniques. Our analysis reveals a C
2-symmetric structure with quasi-perpendicular aromatic rings,
in excellent agreement with crystallographic data. Quantum chemical
calculations and topological analysis identify a stabilizing reciprocal
n→π* interaction between adjacent carbonyl groups that
may contribute to BPO’s thermal resilience compared to other
organic peroxides. Furthermore, we detect several photofragmentation
products, including benzoic acid, benzyne, benzaldehyde, and benzophenone,
providing insights into potential decomposition pathways. This molecular-level
investigation bridges the gap between macroscopic hazard assessments
and fundamental understanding of peroxide reactivity, with implications
for safer handling and rational design of peroxide-based systems.