Optimizing of the production process of dinitropentamethylenetetramine (DPT) using central composite design (CCD) of experiments

Dinitropentamethylenetetramine (DPT) is an important intermediate in the production of cyclotetramethylene tetranitramine (HMX) explosive. This substance is usually produced by nitration of the hexamethylenetetramine, or hexamine, by a solution of ammonium nitrate-concentrated nitric acid and acetic anhydride in glacial acetic acid environment [1-3]. In this research, effect of various factors on the production efficiency of DPT high-energy substance have been statistically modelled and optimized by the central composite design of experiments (CCD) using Minitab software, and multivariate linear regression (MLR) method. Also, necessary quantitative and qualitative analyses, including melting point, CHN elemental analysis, Fourier-transform infrared (FT-IR), and carbon-13 /hydrogen nuclear magnetic resonance spectroscopy have been investigated to identify and confirm the quality of the final product. Experimental investigations show that the four main factors affecting the reaction efficiency, i.e., the amount of nitrating agent ammonium nitrate-nitric acid, reaction temperature, nitrating time and retention time, have significant effect on the product production efficiency. Statistical analyzes show a very good agreement between the presented MLR model and the experimental results, enabling the production of DPT with an efficiency of close to 82%.