Process for the synthesis of 2,6-diamino-3,5-dinitrotoluene

An integrated process for preparing a complex of 2,3,5,6-tetraminotoluene and the aromatic diacid XYTA, wherein the complex is generally described by Formula IV

• wherein X and Y are each independently selected from the group consisting of H, OH, SH, methyl, ethyl, F, Cl, and Br;
• comprising the sequential steps under exclusion of oxygen:
• a) nitration of 2,6-dichlorotoluene (V)
• in a reaction mixture comprising oleum or SO3, nitric acid, and H2SO4
• wherein
• (iv) the concentration of nitric acid is about 2.0 to about 2.3 moles per mole of 2,6-dihalotoluene;
• (v) the concentration of SO3 is about 1 to about 3 moles per mole of 2,6-dichlorotoluene;
• (vi) the concentration of 2,6-dichlorotoluene in the reaction mixture is between about 12 and about 24 weight percent;
• and
• wherein the temperature of the reaction mixture does not exceed 120° C.;
• thereby producing 2,6-dichloro-3,5-dinitrotoluene;
• b) directly separating the 2,6-dichloro-3,5-dinitrotoluene from the reaction mixture by filtration, while recycling the sulfuric acid mother liquor;
• c) washing the 2,6-dichloro-3,5-dinitrotoluene with water or acid then water, then with NH4OH;
• d) aminating the 2,6-dichloro-3,5-dinitrotoluene by forming a reaction mixture comprising a suspension of the 2,6-dichloro-3,5-dinitrotoluene in glycol in the presence of ammonia and about 2 to about 25 wt % water, and heating the reaction mixture to convert the 2,6-dichloro-3,5-dinitrotoluene to 2,6-diamino-3,5-dinitrotoluene;
• e) directly separating the 2,6-diamino-3,5-dinitrotoluene from the reaction mixture formed in step (d) by filtration, washing with glycol, then washing with water;
• f) forming a slurry of the 2,6-diamino-3,5-dinitrotoluene with water and transferring the slurry to a hydrogenation reactor containing a hydrogenation catalyst to form a reaction mixture;
• g) hydrogenating the 2,6-diamino-3,5-dinitrotoluene by contacting the reaction mixture formed in step (f) with hydrogen at a pressure in the range of about 0.31 to about 3.45 MPa and a temperature in the range of about 20° C. to about 100° C. to hydrogenate the 2,6-diamino-3,5-dinitrotoluene, thereby producing 2,3,5,6-tetraminotoluene;
• h) contacting the 2,3,5,6-tetraminotoluene produced in (g) with an aqueous solution comprising 1 to 6 equivalents of acid per mol of 2,3,5,6-tetraminotoluene, optionally heating the solution, thereby dissolving the 2,3,5,6-tetraminotoluene;
• i) filtering the reaction mixture, thereby removing the spent hydrogenation catalyst;
• j) combining the filtered reaction mixture with
• (v) 0 to 5 equivalents of an acid;
• (vi) 0 to 5 equivalents of an organic base or an inorganic base;
• (vii) optionally, a buffer solution;
• and
• (viii) an XYTA source selected from XYTA and M2XYTA (Formula VI)
• wherein M is K or Na,
• and wherein the molar ratio of XYTA to the 2,3,5,6-tetraminotoluene salt is from 1:1 to 1:1.1;
• thereby adjusting the pH of the mixture to between about 3 and about 10 and thereby producing and precipitating the complex generally described by Formula (IV);
• and
• k) cooling, filtering, and washing the precipitated complex.