Abstract:
Hexanitrobenzene is prepared by oxidizing the amine group of pentanitroaniline with H 2  O 2  in H 2  SO 4 . The compound is a high density explosive.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to methods for preparing aryl compounds having a multiplicity of nitro groups attached. More specifically, this invention relates to a method for the preparation of hexanitrobenzene. 
     2. Description of the Prior Art 
     Hexanitrobenzene is of great interest to those concerned with explosives. Aryl compounds with large numbers of nitro groups on the rings are well known to be explosives. A typical example is trinitrotoluene which is more commonly known simply as TNT. Orlova reports a method for preparing hexanitrobenzene in &#34;Chemistry and Technology of High Energy Explosive Substances,&#34; Khimia (1973). However, the authors of this specification were unable to duplicate the results of the Russian author. Accordingly, the authors of this specification, after a considerable amount of experimentation, developed the hereinafter disclosed method for the preparation of hexanitrobenzene. 
     SUMMARY OF THE INVENTION 
     According to this invention, hexanitrobenzene is prepared by reacting pentanitroaniline with H 2  O 2  in H 2  SO 4  at a temperature in the range from 25° to 30° C. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hexanitrobenzene may be prepared by carrying out the procedure set forth in the following specific example. 
     EXAMPLE 
     Pentanitroaniline (1.0 g) is dissolved in 50 mL of fuming H 2  SO 4  (20%S0 3 ). After cooling to 5° C., 5 mL of 98% H 2  O 2  is slowly added, keeping the temperature below 30° C. The solution, protected by a drying tube, is stirred at 25°-30° C. for 24 hours and at 0° C. for 1 hour. The precipitated product is removed by filtration through a sintered glass funnel and washed with concentrated H 2  SO 4  (additional product is obtained by extraction of the filtrate with methylene chloride; the extracts should be worked up immediately and not stored). It is dissolved in pure, dry, warm chloroform and the solution is decanted through a short column of anhydrous MgSO 4 . The filtrate after concentration at 25° C. to a volume of 10 mL and chilling at 0° C. for several hours, deposits small, chunky, pale yellow prisms of hexanitrobenzene: 0.63 g (58%); mp 240°-265° C. dec; concentration of the filtrate gives 0.14 g of additional product, mp 195°-245° C. The first crop on sublimation gives very pale yellow prisms: mp 246°-262° C. (lit: mp 240°-258° C.) (moisture must be excluded during the isolation operations);  13  C NMR (CD 2  Cl 2 )δ 138.7 relative to tetramethylsilane=O (lit. 139.0 ); IR (KBr) 1560, 1320, 887 cm 1  ; mass spectrum, strong m/e at 348 with very little fragmentation. 
     Anal. Calcd for C 6  N 6  O 12  : C, 20.70; N, 24.14. Found: C, 20.67; H, 0.00; N, 23.74. 
     In carrying out the foregoing procedure, 100% H 2  SO 4  may be used in lieu of the fuming H 2  SO 4  specified. Also the times of reaction (24 hours at 25°-30° C.) is not critical. The reaction time may be varied from as little as 5 to 6 hours up to an infinite amount of time. The 1 hour reaction time at 0° C. is not necessary. The hexanitrobenzene precipitates out during the reaction carried on at 25°-30° C. 
     Hexanitrobenzene may be utilized as an explosive in the same manner that other solid, crystalline explosive materials are utilized.