Comparison of the Crystals Obtained by Precipitation of CL-20 with Different Chemical Purity

Abstract

The precipitation of CL-20 with different chemical purity is presented herein. Studies have shown that the first crystallization of the crude CL-20 does not allow achieving the expected polymorphic purity and slightly increases chemical purity. Further precipitation processes result in gradual increase of the chemical purity about 1–2 % and in the improvement of the properties of crystals, i.e. density, polymorphic purity, and sensitivity to friction. This paper attempts a preliminary purification of the crude CL-20 with columns filled with activated charcoal. A material of high purity, obtained by this process, was used in the process of precipitation. As a result of the crystallization a sample of CL-20 was obtained with high chemical purity of 99.5 % and significantly reduced sensitivity to friction (128 N) and to impact (4 J). Additionally, samples of CL-20, recovered from the filtrate after crystallization with a chemical purity of about 88 %, were purified on columns filled with activated charcoal. In this process a significant amount of impurities was removed and the purity was increased to 96 %.