DEGDN

     DEGDN, an acronym for diethylene glycol dinitrate, is a nitrated ester chemically similar to nitroglycerin, although far more stable. It is commonly used in rocket propellants as an energetic plasticizer to increase burning rates and to keep solid propellant formulations plastic and flexible at varying temperatures and to prevent cracking and shrinking. It is also used in explosive compositions for the same reasons and to improve the safety of such compositions. DEGDN is a liquid at room temperature, and while it can be detonated by itself, it is only used in admixture with other explosives because it is so insensitive. DEGDN is stable at room temperature and can be stored for extended periods. It is very toxic and can be absorbed through the skin or inhaled as vapors. Toxic symptoms are similar to nitroglycerin, i.e. bad headaches.

CHEMICALS	APPARATUS
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     Synthesis 1: Under the usual nitrating conditions DEGDN will decompose, or even detonate because of side reactions with the mixed acid. It is also very important to keep reactions temperatures low throughout the procedure to avoid accidents or loss of product. The addition of an organic solvent prevents side reactions and helps keep reactions temperatures low. In a 100-mL beaker kept cool by immersion in a salt-ice bath prepare a mixture of 1.75 mL of nitrating acid consisting of 50.7% nitric acid and 49.3% sulfuric acid. Percentages are by weight and the acids should be as highly concentrated (>99%) as possible (the more water there is the lower the yield will be). Allow the mixed acid to cool for a few minutes and then add 50 mL of n-heptane. Allow the mixture to cool below 10 C before proceeding with the next step. After the acid and solvent mixture has cooled to 10 C, slowly add 0.70 mL of diethylene glycol with very rapid stirring. The heptane solvent should prevent the reaction mixture from rising above 20 C, but if it does be prepared to dump the beaker in ice water to quench the reaction. Allow the reaction to proceed for several minutes and then discontinue stirring. Shortly after the stirring is stopped three layers should form in the beaker consisting of spent acid on the bottom, DEGDN in the middle, and heptane on top. Add the contents of the beaker to a seperatory funnel and again allow the layers to form. Remove and discard the lower acid layer. Collect the now lowest layer of DEGDN in a small Erlenmeyer flask and mix it with several times its volume of concentrated sodium carbonate solution to neutralize any remaining acid. The DEGDN is extracted from the carbonate solution by shaking it with a portion of ethylene chloride in a seperatory funnel. This extract should be transferred to an Erlenmeyer flask and dried by adding anhydrous magnesium sulfate. The ethylene chloride can be removed by gentle heating. Synthesis 2: In a 100-mL beaker prepare a nitrating acid mixture consisting of, by weight, 70 % nitric acid and 30% sulfuric acid. Pour 24 parts of the mixed acid in a separate beaker along with 50 parts of dichlorofluoromethane*. In yet another beaker prepare a mixture of 9 parts of diethylene glycol and 50 parts of dichlorofluoromethane*. Cool the contents of both of the beakers containing the solvent to 8 C in a salt-ice bath. Carefully pour one of the beakers into the other with considerable stirring. After all the chemicals have been mixed the reaction only needs a few minutes to go to completion. A reaction temperature no higher than 11 C should be maintained because the solvent will evaporate off. Stop stirring a let the reactants settle. Two layers will separate consisting of an upper solvent layer containing DEGDN and a lower spent acid layer. Place the mixture in a separatory funnel and drain off the lower acid layer. The solvent layer should be placed in another beaker and the acid added to the separatory funnel. Extract any remaining DEGDN from the acid by shaking with 50 parts of dichlorofluoromethane*, and then combine this extract with the other solvent. The combined solvent should be washed by shaking with a 20 parts of water. The solvent is now allowed to evaporate, either by gently heating or aspiration, and the remaining crude DEGDN is washed with 20 parts of 4% sodium carbonate solution followed by 20 parts of water.

      * The particular choice of solvent for this reaction does not have to be dichlorofluoromethane. A suitable alternative solvent must be a hydrocarbon with at least half of the hydrogens replaced by halogens, and at least one halogen must be fluorine. The solvent must have a low boiling point, typically between 10 and 30 C. Such solvents are available OTC as refrigerant at stores that sell automotive supplies.

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