Patent ID: 7288648

Claim:
A method of crystallizing an epsilon-polymorph of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.0 5,9 0 3,11 ]-dodecane (CL-20), comprising: combining CL-20, at least one organic solvent, and at least one nonsolvent to form a crystallization solution; saturating the crystallization solution; heating the crystallization solution to a temperature of from about 71° C. to about 94° C.; removing the at least one organic solvent from the crystallization solution while retaining a sufficient amount of the at least one nonsolvent to crystallize the CL-20 as the epsilon-polymorph; and separating the at least one nonsolvent from the epsilon-polymorph of CL-20.