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.

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.

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