Selective Nitrations: Laser-Induced Nitrations

The Army uses nitrated compounds as explosives and propellants. There is a special need for propellants with the chemical composition necessary to burn exactly with a minimum of side products which create smoke, but with high energy production. An important part of this process is the ability to selectively nitrate materials. Laser-induced chemistry possesses the potential to drive some reactions in an efficient and selective manner. Laser-induced chemistry may be useful in driving nitration reactions toward specific products. Reported herein are the results of several successful attempts to laser-induce the reaction of nitrogen dioxide with hydrocarbons of 3, 4 and 5 carbons. Specifically, the tunable continuous wave infrared laser was used to drive the reaction between nitrogen dioxide, and propane, n-butane, isobutane, and n- pentane. The major products of the reactions were secondary (tertiary in the isobutane reaction) nitro-hydro carbons, of the same chain length as the reacting hydrocarbon. Some short chain nitrated compounds were also identified. The yield of acting hydrocarbon. Some short chain nitrated compounds were also identified. The yield of 2-nitro-butane observed in the nitration of butane is approximately 20% based on the depletion of nitrogen dioxide. The propane reacted with nitrogen dioxide to produce mostly 2-nitropropane with a smaller yield of 5-9%. The analogous reaction of pentane produced approximately 9% of the major product which is believed to be 2-nitro-pentane. The isobutane nitration resulted in approximately a 10% yield of 2-methyl-2-nitropropane. The results of these laser-induced reactions are contrasted to the corresponding thermal reactions.