Synthesis of N,N,N′,N′-Tetraoctyl-3-oxapentane-1,5-diamide (TODGA) and Its Steam Thermolysis-Nitrolysis as a Nuclear Waste Solvent Minimization Method

The amide based nuclear extractant, N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA), was synthesized by an alternate route. A noncatalytic steam thermolysis and nitrolysis of TODGA was investigated in a SS 316 flow reactor as a nuclear waste solvent minimization method. All the reaction products of steam thermolysis and nitrolysis of TODGA were identified by using gas chromatography-thermal conductivity-flame ionization-mass spectroscopic detection techniques to get the complete mass balance. In the pyrolysis products, C1–C4 hydrocarbon gases, NOx, alkyl amines, and unconverted TODGA were characterized and quantified. The experimental data for the steam pyrolysis of TODGA was obtained in a temperature range of 550–1100 °C at overall atmospheric pressure. A continuous steam pyrolysis of TODGA in a SS 316 flow reactor over a temperature range of 850 to 1000 °C was found to be an irreversible, pseudo-first-order reaction with approximate activation energy of 123 kJ/mol. A comprehensive reaction network model was proposed to include the reaction mechanism of steam thermolysis of TODGA. The present experimental data and product’s statistics of the steam nitrolysis of TODGA estimates that the possibility of the explosive runaway reactions during the nitration of TODGA at elevated temperatures is rare.