BDNPA

     BDNPA, an acronym for bis(dinitropropyl) acetal, is an energetic plasticizer or binder. BDNPA is also called 1,1'-[ethylidenebis(oxy)]bis[2,2-dinitro-propane; bis(2,2-dinitropropyl) acetal acetaldehyde; 1,1-bis(2,2-dinitropropoxy)-ethane; 2,2-Dinitropropanol acetal; and bis(2,2-dinitropropyl) acetal. While not an explosive itself, BDNPA is one of several of a new class of materials designed to replace inert plasticizers with energetic ones. BDNPA finds use as in propellants, plastic explosives, and in gas generating systems like airbags. BDNPA will add extra energy to any explosive or propellant, whereas the traditional binders are inert thus sapping explosive energy. BDNPA is often mixed with its close counterpart BDNPF.

CHEMICALS	APPARATUS
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     Into a dry flask purged with nitrogen prepare a mixture of 2.00 g of 2,2-dinitropropanol and 0.48 g of acetaldehyde. Cool the mixture to 0 C in an ice bath and slowly add 0.96 g of boron trifluoride diethyl etherate over a period of 45 minutes. During the addition the mixture is kept at 0 C, stirred rapidly, and kept under a protective atmosphere of nitrogen. Quench the reaction with 4 mL of water, and then add 10 mL of methyl tert-butyl ether. The reaction mixture is added to a separatory funnel and the aqueous layer is removed. The organic layer is shaken with an excess of 5% sodium hydroxide solution for 30 minutes. The organic layer is washed with a second portion of 5% sodium hydroxide, followed by three 5 mL portions of water. The washed organic layer is added to a small Erlenmeyer flask along with some anhydrous magnesium sulfate drying agent. The solvent is removed by gently heating to 40 C leaving behing pure BDNPA. Final yield is almost 1.3 g or 59%.

      Synthesis 2:
Into a 100-mL flask prepare a mixture of 15 mL of ethylene dichloride, 80 g of 2,2-dinitropropanol, and 19 mL of 96% sulfuric acid. The flask is immersed in a cooling bath and the mixture is stirred for several minutes while the temperature is lowered to 20 C. Add 7.8 g of paraformaldehyde at such a rate as to keep the temperature below 30 C. The mixture is stirred for 1 hour while the temperature is maintained between 25-30 C. Let the mixture sit so it can develop into layers; some methylene chloride is added to aid this process. Add the upper layer to a separatory funnel and extract it with one portion of methylene chloride. The extract is washed with two portions of dilute sodium hydroxide and with two portions of water. The washed extract is dried over anhydrous sodium sulfate. The solvent is removed by vacuum aspiration leaving behind crude BDNPA. The BDNPA is purified by dissolving 40 g in 100 mL of ethyl alcohol. Cool the mixture to 12 C and add some seed crystals of BDNPA. Cool the mixture to -20 C to precipitate the product. Filter to collect the crystals, wash them with water, and allow them to dry. Final yield of pure BDNPA is about 30 g or 76%.

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