Starches nitrate esters

Nitrostarch (NS) is a nitrate ester (more properly a mixt of several nitrate esters) of starch, which is a plant-product polysaccharide of the general formula (CgHujOj) The general molecular formula for NS is [C6H7(OH)x-(0NO2)y]n where x + y - 3, The following empirical relation, similar to that used for NC... 

Nitrotoluenes, Van No strand, NY(1918) 2)M.Kostevitch, "Tarry Matter of Alpha Trinitrotoluene, Part II, Imprd Art Vol-taire,P aris( 1927), 8 3)Sidgwick( 19 37), 259 et seq 4)Davis(1943), 136-7, 147, 149-51 170-1 5>negering( 1950), 139 seq 6) Dept of the Army TM 9-1910( 1955), 146 Alkalies, Action on Nitric Esters. Organic nitrates in general are readily saponified by alkaline solns. A simple metathetical reaction to yield the alkali nitrate and alcohol does not take place instead, as a result of simultaneous oxidation and reduction, alkali nitrite and a variety of products are formed depending on the conditions of the reaction. The resistance of different nitric esters to alkalies varies considerably. Thus, starch nitrate is decomposed much more slowly than cellulose nitrate and amylopectin nitrate still more alowly... 

The most important of the carbohydrate esters of nitric acid are the polysaccharide nitrates, particularly cellulose nitrate or nitrocellulose (NC) and starch nitrate ( nitrostarch ) which is much less used. Nitric esters prepared from other sugars such as saccharose and lactose are not of any importance as explosives. 

Composition Nitric ester of starch. It is not a definite, single compound, but rather a mixture of various esters of different degrees of nitration, measured by the percentage of nitrogen. Like nitrocellulose, nitrostarch is a nitrate and not a nitro compound and the correct chemical name is starch nitrate. However, the term nitrostarch has been generally adopted. 

Starch acetates have been extensively investigated both as to manner of preparation and as to properties. This is in contrast to the other organic esters of starch of which only a few have been prepared, and, of these, only a few characterized. Among the inorganic esters, the starch nitrates have received the most attention and have risen to industrial importance because of their use in explosives. Partly because of this use and the secrecy attending their manufacture, a full disclosure of the preparation and properties of starch nitrates has not been published. 

Nitric acid esters of starch are the oldest known starch derivatives and are the only starch esters commercially produced on a large scale. Like cellulose nitrates, the starch nitrates are excellent explosives. They are used extensively in blasting compositions, for quarrying and for certain types of mining. Tapioca starch was used mainly for commercial nitrations in the United States until the advent of World War II and the disruption of supplies made it necessary to nitrate com starch. This transition has been accomplished with little difficulty, although the exact process used is a trade secret. 

Structure of cellulose polymer and determination of molecular weight Pyrolysis of nitrocellulose Thcrmochemical properties of nitrocellulose Mixed esters nitrates and sulphates Stabilization of nitrocellulose Knccht compound Manufacture of nitrocellulose Semi-continuous methodof Bofors-Nobel-Chematur Drying of nitrocellulose Safety in the manufacture of nitrocellulose Starch nitrates (nitrosiarch)... 

The nitrate ester is the oldest known derivative of starch. Since the beginning of this century, it has been, industrially, by far the most important, high-substituted starch derivative. 

Will and Lenze s studies, published in 1898, reflect an increasing appreciation of this vital problem of adequate stabilization of the nitrate ester. They fractionated starch nitrates (produced by the inferior technique of initial dissolution in nitric acid) by means of acetone-alcohol, and the fraction insoluble in alcohol was purified by several boilings in alcohol. A maximum nitrogen content of 14.04% was reported. This figure is possible but, taking into account the analytical accuracy of the time, was probably an inaccurately high value. 

That the age-old problem of better stabilization was still present as late as 1920 was shown by the issuance of a U. S. patent to B. Flurscheim for stabilizing starch nitrate by means of cyanamid or calcium cyanamid on the other hand, G. R. Anchors, quite evidently unimpressed by the difficulties of obtaining a stable nitrate ester from starch, undertook the nitration of puffed cereals in mixed acids, using soap for a stabilizer ... 

Pyroxylin Starch nitrate UN0146 UN1337. A nitric ester of starch, probably the octonitrate used for blasting explosives, either alone, or by mixing 10% of it with a mixture of sodium nitrate and carbonaceous material. See pyroxylin [9004-70-0]. 

Derivatives of starch. The esters and ethers of starch do not find the wide field of uses of their cellulose counterparts. Starch nitrate is used as a high explosive. Slight derivatization of starch yields a number of commercially useful products. 

The problem of how to stabilize nitrostarch has been solved by different means, but the majority of stabilization processes remain obscure as patent secrets. None the less, from certain observation some general conclusions can be made. It was early observed by Bechamp [13] that nitrostarch obtained by nitration in nitric acid alone is more stable than one obtained by means of nitric acid mixed with sulphuric acid. This has been confirmed experimentally by Hackel and T. Urbanski [18], and seems likely to be explained by the formation of starch sulphates or mixed nitric and sulphuric esters of starch. 

In unmodified cellulose the hydroxyl groups give a large amount of hydrogen bonding which leads to insolubility in most solvents. On the other hand if these arc changed by chemical reactions to ether or ester groups a much more tractable material results. Cellulose acetate, butyrate and nitrate methyl and ethyl ether and carboxy methyl ether are widely used modified celluloses. Starches also are modified, but much less commercial success has been had with them. 

In 1833 Braconnot obtained nitric esters of cellulose and starch by acting with nitric acid on plant fibres and starch, at low temperature, hi 1834 Mitscherlich nitrated benzene to nitrobenzene. But it is only since 1842, when Zinin reduced nitrobenzene to aniline, that rapid development of the chemistry of nitro compounds and their application to organic industry has occurred. 

SAFETY PROFILE A very dangerous fire and explosion hazard when exposed to heat, flame, shock, or oxidizers. It is a powerful high explosive. Nitrostarch is not a definite compound, but a mixture of various nitric acid esters of starch with different degrees of nitration. When heated to decomposition it emits toxic fumes of NOx. See also NITRO COMPOUNDS. 

---