Nitrostarch, also called NS; nitrate d'amidon; nitrostaerke; and staerkenitrat, is actually a mixture of several nitrate esters of starch. Yes, starch is the plant product that can be purchased in the grocery store. Since this is really a variety of nitrated products the formula is [C6H7(OH)x(ONO2)y]n where x+y=3 and n is any whole number from one on up. The exact composition depends on the reaction conditions during the nitration. Nitrostarch found a use as a filler in hand grenades back in WWII, and also in mining explosives. Nitrostarch was first made when H. Barconnot nitrated cellulose and starch back in 1833. At that time nitrocellulose and nitrostarch were thought to be one and the same. Then A. Béchamp applied various methods of separating them in 1862. The US first began to produce nitrostarch in 1888 under the name Volney Powder. Various companies produced nitrostarch throughout both world wars, but the US emerged as its sole manufacturer.
|nitric acid||500-mL beaker|
|sodium bicarbonate||graduated cylinder|
Prepare a mixture of 100 mL of 98-100% nitric acid and 138 mL of 95-100% sulfuric acid in a 500-mL beaker by pouring one acid into the other. Add the acids slowly as a lot of heat will be generated, keep the beaker in a salt-ice bath to cool it. Slowly add 100 g of starch to the acid mix while stirring and maintain a temperature of 10-12 °C for 1 hour and 50 minutes, continue stirring during the nitration. You can increase the rate of the reaction by holding the temperature to as much as 40 °C, but keep in mind higher temperatures increase the chance of accidents. Information on purifing and stabilizing the product is sketchy because of trade secrets, I suggest adding the nitrostarch to water and bring it to a boil. Then add the nitrostarch to another batch of water in which a small amount of base has been added, like sodium bicarbonate, and bring to a boil. This should stabilize and purify the nitrostarch. The nitrostarch is then filtered to collect it and dried. You will need a graduated cylinder for measuring liquids, a stirring rod or magnetic stirrer for mixing, and a thermometer to monitor the temperature.
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