Esters nitrates

Nitrate esters are characterized by -O-NO2 bonds in their structures. Typical nitrate esters used in propellants and explosives are nitrocellulose (NC), nitroglyc-erin(NG), triethyleneglycol dinitrate (TEGDN), trimethylolethane trinitrate (TMETN), diethyleneglycol dinitrate (DEGDN), and nitratomethyl methyl oxetane (NIMO). These nitrate esters are aU liquid at room temperature, with the excephon 

NC is an energetic nitropolymer consisting of a hydrocarbon structure with -O-NO2 bonds as oxidizer fragments. In general, NC is produced from the cellulose, C6H702(0H)3 j of cotton or wood, which is nitrated using nitric acid (HNO3) to introduce -O-NO2 bonds into its structure. 

NC decomposes in an autocatalytic reaction with the evolution of NO2 as a result of breakage of the weakest bond of -O-NO2. The reaction between 363 K and 448 K is a first-order process and the activation energy is 196 kj moh. The remaining fragments form aldehydes such as HCHO and CH3CHO. The reaction between NO2 and these aldehydes produces heat and combustion gases. 

NG has a relatively low molecular mass of 227.1 kg kmoh. It is a liquid at room temperature, but solidifies below 286 Since NG is shock-sensitive and easy 

The simplest nitrate ester is methylnitrate, which has the chemical structure CH30N02. The decomposition process is given by119 221 

The first two reaction schemes are endothermic, but the overall reaction is exothermic and the final flame temperature is 1800 K. The observed pressure dependence of the burning rate follows a second order rate law the overall activation energy is consistent with the oxidation reaction by N02, which is the slowest and 

The primary step in the decomposition of ethylnitrate (C2H50N02) is again the breaking of the C2H50-N02 bond[23 and the decomposition rate obeys a first order law. The decomposition process of ethylene glycol dinitrate is1221  

N02 is then converted to NO by the oxidation reaction with RCHO. 

As is evident from the experimental measurements, most kinds of nitrate esters appear to decompose to N02 and C-H-O species with the breaking of the 0-N02 bond as the initial stage. A strong heat release occurs in the gas phase near the decomposing surface due to N02 reduction to NO with the accompanying oxidation of C-H-O species to H20, CO, and C02. NO reduction, however, is slow, and the reaction is not observed in the decomposition of some nitrate ester systems. Even when the reaction occurs, the heat release does not contribute to the heat feedback to the surface because the reaction occurs remote far from the surface. 

Nitrocellulose or gun cotton was discovered by Braconnot (France, 1833) and patented by Schonbein (1846) (Fig. 1). It is speculated that in order to determine whether the action of nitric acid was a reaction or merely a sorption into fibrous material, Sobrero (1846) treated glycerin, a liquid, with nitric acid and found a true reaction took place. Hence, nitrocellulose and nitroglycerin were discovered within a decade of each other, but neither found widespread use until the 1860 s when methods of stabilizing them were devised. Between 1865 and 1868, Abel patented improved preparations of nitrocellulose. He found that pulping allowed impurities, such as residual acid, to be more easily washed out by poaching and resulted in improved stability. The Abel stability test is named after him[5]. 

While complex nitrate esters, such as nitrocellulose and nitroglycerin, were the first to find application as explosives, understanding the mechanisms of nitrate ester decomposition was accomplished through the study of simpler compounds [11-16]. Ethanol nitrate was examhed by numerous researchers, and they conceded the first, and rate-determining, step was reversible loss of 

A comprehensive study examined the thermal stability and decomposition mechanism of a large number of primary, secondary, and tertiary mononitrates n-pentanol, 3-buten-l-ol, ethanol, neopentanol, 2- 

---

Table 7. Properties of Explosive Aliphatic Nitrate Esters...

R. Barefoot, "Compatibihty of Nitrate and Nitrate Esters," ia Conference on Compatibility of Propellants, Explosives, and Pyrotechnics with Plastics and Additives, Report NC-02P, AD PA, Washiagtoa, D.C., 1976, p. l-E-22. 

The hydroxyl groups on glycols undergo the usual alcohol chemistry giving a wide variety of possible derivatives. Hydroxyls can be converted to aldehydes, alkyl hahdes, amides, amines, a2ides, carboxyUc acids, ethers, mercaptans, nitrate esters, nitriles, nitrite esters, organic esters, peroxides, phosphate esters, and sulfate esters (6,7). 

Esters of nitro alcohols with primary alcohol groups can be prepared from the nitro alcohol and an organic acid, but nitro alcohols with secondary alcohol groups can be esterified only through the use of an acid chloride or anhydride. The nitrate esters of the nitro alcohols are obtained easily by treatment with nitric acid (qv). The resulting products have explosive properties but are not used commercially. 

G. E. Manser, "Nitrate Ester Polyether Glycol Prepolymer," JANNAF Propulsion Committee Meeting, New Orleans, La., Chemical Information Agency, John Hopkins University, Baltimore, Md., 1984. 

Composition of nitrating bath Cellulose nitrate ester ... 

Generally, the successful conversion of 20-ketopregnanes to 17-hydroxy-androstanes with peracids requires the protection of other ketones, with the exception of those at C-11, and possibly C-12 e.g., as ketals or cyanohydrins ) and isolated double bonds e.g., as dibromides). Unprotected hydroxyl groups do not interfere, except, as expected, a 17a-hydroxy-20-keto steroid is oxidized to the 17-ketone. The use of nitrate esters to protect... 

Nitrocellulose, of the resins used in these end uses and in car refinishing, is the nitrate ester of cellulose. The structure is linear and a wide range of (high) molecular weights is available as well as various degrees of nitration ... 

This change in editorial leadership has resulted, perhaps inevitably, in a change in editorial policy which is reflected in the contents of Volume 8. There has been a marked de-emphasis on the inclusion of organic parent compounds followed by an exhaustive and voluminous cataloging of azide, azido, azo, diazido, diazonium, diazo, nitro, dinitro, polynitro, hitr amine, nitrate (esters and salts), dinitrate, poly nitrate, nitroso, polynitroso, chlorate, perchlorate, peroxide, picrate, etc, derivatives — regardless of whether any of these derivatives exhibit documented explosive or energetic properties. Only those materials having such properties have been included in this volume... 

Analytical. Mannitol Hexanitrate can be hydrolyzed in basic soln and the soln acidified in the presence of NITRON to quanty ppt NITRON nitrate (Ref 16). A procedure is described for. the quant detn of nitrate esters, including Mannitol Hexanitrate, in the presence of aromatic nitro compds in Ref 17. It gives a yellow color when treated in et ale or acet with 5% aq K hydroxide, then 5% aq ammonia (Ref 24), It can be quanty detd by reduction with Devarda s alloy (Encycl 5, D-l 110) or A1 wire in aq et ale and titration of the evolved... 

O-nitration, in which a nitro group is attached to an oxygen atom to form a nitrate ester,... 

Ph. Naoum, Nitroglycerin und Nitroglycerin-sprengstoffe , Springer, Berlin (1924) is the standard reference on NG, EGDN other nitrate esters... 

Nitrate esters such as NG EGDN are made using MA contg 30-70% HN03, 35-70% H2S04 and 0—10% H20. The nitric acid content ot the MA is usually 20% in excess of stoichiometric... 

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... 

At best, expl power i a somewhat nebulous quantity. If we consider relative power as measured in a Ballistic Mortar or Trauzl Block, then OB correlates reasonably well with relative power, provided these comparisons are made for similar expls. This is illustrated in Fig 1, where Ballistic Mortar measurements axe respectively correlated with OB for nitro, nitramine, nitrate ester and aluminized expls. In general Ballistic Mortar measurements are more reproducible than Trauzl Block data. Consequently we have shown these in preference to Trauzl Block measurements. Correlation between Trauzl block data and OB are reported in Refs 1 8... 

Unlike other nitrate esters, PETN does not form a colloid soln with NC... 

Due to its symmetrical structure, Pentaery-thritol Tetranitrate is highly resistant to many reagents. Thus PETN differs from the majority of nitrate esters by not being readily decompd by sodium sulfide at 50°. On the other hand, it is decompd quite quickly by boiling in a ferrous... 

---