HNS

     HNS, an acronym for 2,2',4,4',6,6'-hexanitrostilbene, is a heat resistant high explosive developed at the Naval Ordinance Laboratory in the 1960s. Other names include 1,1'-(1,2-ethenediyl)bis[2,4,6-trinitrobenzene]; 1,2-bis-(2,4,6-trinitrophenyl)-ethylene; hexanitrodiphenylethylene; and JD-X. It is commonly used as a booster charge and in detonating cord. HNS det cord is commercially utilized in aircraft and spacecraft for blowing open canopies. HNS is also used in oil wells where its heat resistance is useful. HNS is also quite stable to shock, friction, and electrostatic discharge, in fact nothing short of a detonation shockwave can set this stuff off. HNS is manufactured in four grades, type I, II, III, and IV that refer to crystallized HNS of differing particle size and surface area. Type I HNS has a particle size of 1-5 microns, type II HNS has a particle size of 100-300 microns, type IV HNS has a surface area of 5 to 25 m2/g

CHEMICALS	APPARATUS
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     Synthesis 1: Prepare a solution of 1.2 g of HNBB and 0.05 g of copper sulfate in 15 mL of DMF. Bubble a strong current of air into this solution over a period of 40 hours to complete the reaction. Filter to collect the product, wash with acetone, and allow to dry. Concentrated ammonium hydroxide (0.1 g) can be used in addition to or in place of copper sulfate. Yields can also be marginally increased by heating the solution to 70 C during the oxidation. This reaction can be scaled up as needed. A variant of this reaction is to use a solution of 1.2 g of HNBB, 0.6 g of anhydrous copper sulfate, and 2 drops of 30% ammonium hydroxide in 5 mL of DMF, stir for 4 hours at 30 C, and filter as above. Yield is 79%. Synthesis 2: Prepare a solution of 1.2 g of HNBB and 0.67 g of quinone in 15 mL of DMSO. Heat the mixture to 95 C, with stirring, for 3 hours. After the heating is complete add a large volume of water to precipitate the product. Filter to collect the crystals and add them to a small beaker of hot acetone. HNS is insoluble in acetone, but the byproducts of this reaction should be taken up in solution. Filter to collect the crystals and allow to dry. Yield is about 33%. A significantly larger yield (83%) can be had by using hexamethylphosphoramide in place of DMSO and heating to only 70 C. One can also increase the yield by adding 0.5 g of pyridine as a co-catalyst. Synthesis 3: Prepare a solution of 1.2 g of HNBB and 1 g of bromine in 25 mL of pyridine. Stir this mixture for 3 hours at room temperature, and then add it to an excess of water to precipitate the product. Filter to collect the crystals, add them to 50 mL of acetone, and stir for 30 minutes. Again filter to collect the crystals and allow them to dry. Final yield of purified HNS is about 1 g or 83%. Synthesis 4: Prepare a solution of 1.2 g of HNBB, 1.2 g of bromine, and 0.6 g of pyridine in 25 mL of DMF. Heat the solution, with stirring, to 70 C for 4 hours, and then add it to an excess of water to precipitate the product. Filter to collect the crystals, add them to 50 mL of acetone, and stir for 30 minutes. Again filter to collect the crystals and allow them to dry. Final yield of purified HNS is about 92%. It is possible to use p-dioxane (yield 67%), THF (yield 83%), or acetonitrile (yield 92%) in place of DMF in this reaction. It is also possible to use 1 g of anhydrous sodium carbonate (yield 17%), 2 g of sodium bicarbonate (yield 33%), or 1 g of magnesium oxide (yield 42%) in place of pyridine. Synthesis 5: Prepare a mixture of 1.2 g of HNBB, 1.2 g of bromine, and 1.2 g of pyridine in 50 mL of chlorobenzene. Heat the solution, with stirring, to 100 C for 1 hour, and then allow it to cool to room temperature. Decant off the chlorobenzene and filter to collect the crystals, add them to 50 mL of acetone, and stir for 30 minutes. Again filter to collect the crystals and allow them to dry. Final yield of purified HNS is about 100%. Synthesis 6: Prepare a solution of 15 g of TNT dissolved in 100 mL of THF and 50 mL of methyl alcohol. Cool this solution to 5 C. Prepare a second solution of 15.75 g of sodium hypochlorite diluted with enough water to make 100 mL. Cool this solution to 5 C. Prepare a third solution of 2.87 g of trimethylamine hydrochloride diluted with enough water to make 14.4 mL. Slowly add, with rapid stirring, the TNT solution to the hypochlorite solution at such a rate as to keep the temperature below 15 C. At precisely 90 seconds after the addition is begun add the trimethylamine solution. After all of the hypochlorite solution has been added allow the mixture to stand at 15 C for 1 hour. Filter to collect the precipitate, wash it with methyl alcohol, and then wash it with hot acetone. After drying the final yield is about 7.5 g or 50%. Synthesis 7: Prepare a solution of 10 g of TNT in 50 mL of THF and 1000 mL of methyl alcohol. Cool this solution to 0 C. Prepare a second solution of 35 mL of Clorox bleach (5% sodium hypochlorite), 0.5 g of sodium hydroxide, and 65 mL of water. Slowly add the bleach solution to the TNT solution dropwise over a period of 5-10 minutes. By the end of the addition the reaction temperature should have risen to 35 C. Allow the reaction to stand for 15 minutes to allow for full precipitation of the product. Filter to collect the product, wash it with methyl alcohol until the washings are colorless, and dry in an oven at 100 C to constant weight. Final yield is about 7.9 g or 79%. The HNS may be purified by adding to hot acetone, refluxing for 2 hours, filtering, and drying in an oven at 100 C.

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