# A Water-Based and Continuous-Flow-Usable Cascade: Sustainable Synthesis of Tetrazolo-Fused Heterocycles

## TL;DR

This paper presents a sustainable, water-based method to synthesize a new high-nitrogen explosive compound using continuous-flow technology.

## Contribution

A novel water-based cascade reaction integrated with continuous-flow technology for synthesizing nitrogen-rich energetic materials.

## Key findings

- AHTO was synthesized with 90.8% yield and 98.1% purity in a 3-hour flow reaction.
- The method eliminates intermediate isolation and reduces toxic solvent use.
- NHTO, a potential metal-free primary explosive, was derived from AHTO.

## Abstract

The innovation of energetic materials is frequently hampered
by
economic inefficiency and safety concerns. Emerging cascade reactions
could overcome existing bottlenecks and accelerate next-generation
energetic materials with enhanced scalability and reduced risks. In
this work, a water-based cascade reaction has been applied to obtain
6-amino-7,8-dihydrotetrazolo­[5,1-f]­[1,2,4]­triazin-8-ol
(AHTO), a new nitrogen-rich energetic compound. Using
water as a green, multifunctional medium, this strategy achieves three
critical advances: (1) elimination of intermediate isolation through
cascade reaction integration, (2) minimization of toxic solvents and
hazardous reagents, and (3) stabilization of sensitive tetrazolo intermediates.
The inherent safety benefits of water-mediated chemistry are further
amplified through microchannel continuous-flow technology, leading
to an all-round improvement. Finally, AHTO was obtained
in a 90.8% crystallization yield and a 98.1% HPLC purity in a 3 h
flow reaction. After nitroamino derivatization, 6-nitroamino-7,8-dihydrotetrazolo­[5,1-f]­[1,2,4]­triazin-8-ol (NHTO) was prepared as
a new potential metal-free primary explosive.The integration of cascade
with flow chemistry will accelerate the development efficiency of
energetic materials while balancing economic, safety, and environmental
considerations.