A New Recycling Technique of Trifluoroacetic Acid in Synthesis of LLM-105 Explosive

Trifluoroacetic acid (TFA) is corrosive and toxic,which is hard to decompose by chemical reaction and micro-biological degradation[1 -2].However,TFA is largely used for the nitrogen oxidation reaction to obtain 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105).Common industrial separation methods such as distillation can not be utilized for recovery of TFA because of a maximum boiling azeotrope (20.6 wt ％ water,boiling at 105.5 ℃ [3]) formed by TFA and water.Till now,there is few report about the separation method of TFA-H2O.Deng[4] et al.studied the recovery of TFA liquid in the synthesis of LLM-105 explosive,the operation processes included neutralization using strong base,concentration,acidation and distillation.Mahajan[5] et al.investigated the feasibility of using reactive distillation to recover TFA through esterification with 2-propanol,but this method was aimed to dilute aqueous solution,which is unsuitable for concentrated aqueous solution. Considering above,we explored a new broken azeotropic technique to recover TFA by adding solvent A,and then employ atmospheric distillation to recove TFA for synthesis of LLM-105.The process diagram is shown in Scheme 1.

Trifluoroacetic acid （TFA） is corrosive and toxic, which is hard to decompose by chemical reaction and micro-biological degradation^[1-2]. However, TFA is largely used for the nitrogen oxidation reaction to obtain 2,6-diamino-3,5-dinitropyrazine- 1-oxide （LLM-105）.