# Mechanically driven stainless steel-initiated activation of S–H bonds to construct disulfides

## TL;DR

A new green method uses stainless steel to create disulfides without harmful chemicals or expensive metals.

## Contribution

A mechanochemical method for disulfide synthesis using stainless steel without solvents, oxidants, or catalysts.

## Key findings

- Stainless steel nanoparticles enabled efficient disulfide synthesis with 41–99.9% yields under ambient conditions.
- The process uses a radical-mediated pathway dominated by iron species, preventing over-oxidation.
- The method is environmentally friendly and tolerant to a wide range of substrates.

## Abstract

Disulfides are important scaffolds in biologically active molecules and pharmaceuticals; however, their traditional synthesis method relies on costly precious metals, toxic solvents, oxidants, and harsh reaction conditions. Herein, we report a mechanochemical strategy enabling solvent-, oxidant-, catalyst-, and auxiliary abrasive-free construction of disulfides via stainless steel-induced S–H activation. Stainless steel nanoparticles (SS NPs) generated during ball milling facilitated efficient oxidative coupling of thiols under ambient conditions, achieving 41–99.9% yields within 30–90 minutes. The mechanistic studies confirmed the synergistic radical-mediated pathway dominated by iron species, effectively suppressing over-oxidation. This green approach eliminated environmental burdens while offering broad substrate tolerance, advancing sustainable disulfide synthesis for pharmaceutical and material applications.

We developed a mechanochemical strategy for the solvent-, oxidant-, exogenous catalyst-, and auxiliary abrasives-free synthesis of symmetrical and unsymmetrical disulfides via stainless steel-induced S–H activation.