Novel strategies for the safe chemical degradation of organic peroxide explosives: A mechanistic investigation

Conventional strategies of explosives disposal are unsuitable for Organic Peroxide Explosives (OPEs) due to their extreme sensitiveness to initiating stimuli. A gentle, chemical means of degrading OPEs is a highly desirable way to safely remove the explosive threat in the field. Previous studies toward this goal have centred on triacetone triperoxide (TATP), using Brønsted-acid-catalysed degradation or the use of redox reactions to effect degradation. Few of these studies conducted detailed analysis of underlying mechanisms. Hazards such as unacceptable risk of detonation, formation of toxic volatile gases or other sensitive peroxides, and long reaction times make the strategies proposed to date unsuitable for use outside the laboratory.This thesis opens with a review of the TATP degradation literature, highlighting key features and limitations in the acidic and redox strategies. In experimental work, a model OPE, tripentanone triperoxide (TPTP) was synthesised, fully characterised and shown to reduce certain laboratory hazards. Acidic degradation experiments using TPTP, monitored by GCMS, showed its reaction mechanism was analogous to that of TATP, and also identified that the hydroperoxide degradation intermediates were highly active Baeyer-Villager (BV) oxidants. The centrality of these reactive hydroperoxides to effective degradation via acidic and redox mechanisms was demonstrated using chemical and electrochemical experimentation, as was the difficulty of reducing cyclic peroxides. A novel and extremely fast degradation reaction of TATP, TPTP and other OPEs with metal-based Lewis acids was identified and a mechanism proposed based on the results of controlled reactions monitored by NMR, FTIR and GCMS. The reaction products suggest that the reaction proceeds via a concerted Baeyer-Villiger-type mechanism, highlighting the potential of BV chemistry as a strategy to degrade OPEs to safe products. A field-relevant, catalytic approach to safe degradation via BV chemistry was then developed utilising both Brønsted and Lewis acids, and strategies for its further refinement proposed. This is the first study to take a cohesive ‘acid-redox’ approach to the degradation of OPEs, and provides a new strategy for the design of a field-relevant method for the safe neutralisation of these hazardous materials