Summary: | The problem whether 1-hydroxylmethyl-3,5,7-trinitro-1,3,5,7-tetraazacyclooctane is the key active intermediate for the synthesis of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) from urotropine or 3,7-dinitro-1,3,5,7-tetraazabicyclo[3.3.1]nonane (DPT) remains to be illuminated for decades. In this paper, the hydrolysis and nitrolysis of the esterified intermediate 1-acetoxymethyl-3,5,7-trinitro-1,3,5,7-tetraazacyclooctane (PHX) were studied to solve the long-standing puzzle. The 1H NMR spectrum and 13C NMR spectrum of the 1-hydroxymethyl-3,5,7-trinitro-1,3,5,7-tetraazacyclooctane were detected by tracking the hydrolysis of PHX, which provide direct experimental evidences for its existence. Meanwhile, it was found that 1-nitroso-3,5,7-trinitro-1,3,5,7-tetraazacyclooctane (MNX) is a stable intermediate in the nitrolysis of PHX to generate HMX, and the presence of small amounts of water in the nitrolysis of PHX not only stimulate the redox reaction between nitric acid and formaldehyde but also promote the reaction by hydrolyzing PHX to corresponding N-hydroxymethyl derivative, which verify that 1-hydroxymethyl-3,5,7-trinitro-1,3,5,7-tetraazacyclooctane is the key active intermediate in the synthesis of HMX.
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