Nitric esters decomposition rate

It is necessary to take into consideration the fact that the decomposition of nitric esters has an autocatalytic character water and nitrogen dioxide formed during the decomposition lead to the formation of nitric and nitrous acids which accelerate the reaction of decomposition of the nitric ester. The influence of nitric acid on the rate of decomposition of nitroglycerine was studied by Roginskii [79] and is described below. 

A number of authors have tried to express the decomposition rate of nitric esters in mathematical formulae. Thus Berthelot [77] expressed the relation between the decomposition rate of nitric esters and the temperature as ... 

Nitrocellulose, like all other nitric esters with the possible exception of PETN,.is intrinsically unstable, even at ordinary temperatures. Yet the decomposition of a thoroughly purified sample is remarkably slow. Koehler and Marqueyrol100 have made a careful study of the decomposition of nitrocellulose at various temperatures in the vacuum of a mercury pump. They found that it evolved gas at the rate of about 0.7 cc. per gram per day at 100°, 0.01 cc. per gram per day at 75°, and 0.0001 cc. per gram per day at 40°. 

Oxalic and malonic acids, as well as a-hydroxy acids, easily react with cerium(IV) salts (Sheldon and Kochi, 1968). Simple alkanoic acids are much more resistant to attack by cerium(IV) salts. However, silver(I) salts catalyze the thermal decarboxylation of alkanoic acids by ammonium hexanitratocerate(IV) (Nagori et al., 1981). Cerium(IV) carboxylates can be decomposed by either a thermal or a photochemical reaction (Sheldon and Kochi, 1968). Alkyl radicals are released by the decarboxylation reaction, which yields alkanes, alkenes, esters and carbon dioxide. The oxidation of substituted benzilic acids by cerium(IV) salts affords the corresponding benzilic acids in quantitative yield (scheme 19) (Hanna and Sarac, 1977). Trahanovsky and coworkers reported that phenylacetic acid is decarboxylated by reaction with ammonium hexanitratocerate(IV) in aqueous acetonitrile containing nitric acid (Trahanovsky et al., 1974). The reaction products are benzyl alcohol, benzaldehyde, benzyl nitrate and carbon dioxide. The reaction is also applicable to substituted phenylacetic acids. The decarboxylation is a one-electron process and radicals are formed as intermediates. The rate-determining step is the decomposition of the phenylacetic acid/cerium(IV) complex into a benzyl radical and carbon dioxide. 

Concentrated, oxidising acids such as sulfuric, nitric and chromic acids which cause decomposition the rate of decomposition may be accelerated in the presence of metals, for example, zinc and iron. Attacked by bromine and fluorine even at room temperature. Unsuitable for use in contact with aromatic and chlorinated hydrocarbons, ketones, nitro-compounds, esters and cyclic ethers these penetrate the PVC and cause marked swelling. Can have a high impact strength but can be very notch sensitive. Methylene chloride can be used to detect an under-gelled compound. 

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