explodes at 160 °C
|mannitol hexanitrate||molecular mass
Mannitol hexanitrate, or nitro mannitol, is a somewhat unstable primary explosive compound. Nitro mannitol is prepared by nitrating the sugar mannitol. Mannitol or, mannite, is not your everyday sugar so do not expect to find any in the grocery store. Mannitol comes in two stereoisomeric forms called L-mannitol and D-mannitol. A stereoisomer is a pair of molecules that are mirror images of each other, same formula but arranged differently. Like your hands they are equal but opposite. When a beam of polarized light passes through a solution of a stereoisomer and the angle changes, it is optically active. Polarized light are beams of light traveling in the same plane, sunglasses polarize light so only light waves of one plane, usually vertically, reach your eyes. If vertical light is rotated to horizontal the angle has changed. Light rotated left is called levorotatory, abbreviated L. Light rotated to the right is called dextrorotatory, abbreviated D. Why the lecture? First of all I love stereoisomerism, and second there is always a chance that chemicals will react differently if L and D. Now you know. In all probability the L or D mannitol will synthesize nitro mannitol. The difference commonly affects biological reactions. This explosive was first prepared back in 1847 by A. Sobrero when he mixed mannitol with nitric acid. It was prepared on a lab scale throughout the 19th century and was manufactured in the Royal Arsenal at Turin, Italy until 1853 when it blew up. Mannitol hexanitrate is also called nitromannite or hexanitromannite, the French call it nitromannitane, the Germans and Italians call it nitromannite, and the Russians call it mannitazotnokislyy. Mannitol hexanitrate is used as a secondary explosive and in some cases as a safety blasting cap. It can be stored safely with the addition of 5-10% sodium, potassium, or lithium salicylates.
|ethyl alcohol||dropping funnel/buret|
|mannitol||300-mL Erlenmeyer flask|
|nitric acid||graduated cylinder|
|sodium bicarbonate||sintered-glass funnel|
Cool 50 mL of 99% nitric acid in a 300-mL Erlenmeyer flask to 0 °C in a salt-ice bath. Slowly add 10 g of mannitol in small amounts at such a rate as to keep the temperature below 0 °C. After all the mannitol is dissolved, add 55 mL of 99% sulfuric acid from a dropping funnel, or buret, at such a rate that the temperature is held below 0 °C. The porridge-like mass is filtered on a sintered-glass funnel, washed with water, 5% sodium bicarbonate, and again with water. The crude product is dissolved in warm ethyl alcohol, filtered, and cooled to deposit crystals of pure mannitol hexanitrate. A second crop is obtained by heating the filtrate and washings to boiling, adding water until the solution is cloudy, and cooling. The yield is 23 g or 96.6% of the theoretical yield. You will need a graduated cylinder for measuring liquids, and a thermometer to monitor the temperature.
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