Statistical Optimization of a Novel Approach for the Reductive Debenzylation of 2,4,6,8,10,12-Hexabenzyl-2,4,6,8,10,12-hexaazaisowurtzitane Using Pd@SiO2 Nano Catalyst

The synthesis of 2,6,8,12-tetraacetyl-4,10-dibenzyl-2,4,6,8,10,12hexaazaisowurtzitane (TADB), from 2,4,6,8,10,12-hexabenzyl-2,4,6,8,10,12hexaazaisowurtzitane(HBIW) is a key step in the preparation of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW or CL-20). In this study, a novel highly efficient nano catalyst based on Pd@SiO2 was used for the reductive debenzylation of HBIW. It is notable that an orthogonal array design OA9 was applied as a statistical optimization method for the synthesis of TADB. The current application of the Taguchi method in optimizing the experimental parameters of the TADB synthetic procedure was successful. TADB was synthesized by investigating the effect of the reaction conditions, such as catalyst percentage, time (h) and temperature (°C). The effects of these factors on the yield of TADB were evaluated quantitavely by the analysis of variance (ANOVA). The Pd@SiO2 nano catalyst, consisting of a palladium core with SiO2 monolayer shells, was synthesized and characterized by SEM, TEM and IR spectroscopy. The optimum condition indicated that the use of fresh Pd@SiO2 nano catalyst provides a high yield (90%). The use of Pd@SiO2 nano catalyst after recovery gave a yield of 65%.