Hydrolysis and denitration

The general aspect of the problem of hydrolysis has been discussed already (p. 7). Here some particular points on hydrolysis of nitrocellulose will be briefly described. 

Nitrocellulose, treated with different hydrolysing agents such as aqueous solutions of alkalis, does not yield cellulose and the corresponding metal nitrate, but a range of highly variable decomposition products of cellulose as well as of inorganic substances. 

Different authors have isolated definite compounds from the products of alkaline hydrolysis of nitrocotton. Wolfrom et al. [42] enumerate the compounds that are produced by hydrolysis of nitrocellulose in the presence of acids and bases inorganic nitrates and nitrites, cyanides, 

Most of these products have been detected by the earliest investigators of nitrocellulose, such as Vohl [43], Bechamp [44], Hadow [45], Will [46] and M. Bert-helot [47]. 

In the presence of solid sodium hydroxide the reaction can proceed so quickly and violently that it can bring about ignition of the nitrocotton. 

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Cross-linking t Increasing the viscosity by means of cross-linking) Hydrolysis and denitration Other reactions... 

Further, the stabilization boiling of the nitrated cellulose exerts an express influence on the solubility of nitrocellulose. It causes the substance to become more soluble due to partial depolymerization and denitration. (A certain, insignificant decrease of nitrogen value occurs owing to partial hydrolysis). According to Bruley [54] the following relationship exists ... 

Formic Acid Denitrations. Simulated solutions were subjected to laboratory formic acid denitrations (Figures 2 and 3). The most usable free acid concentration for the simulated solutions was obtained when a formic acid to free acid ratio of about 1.6 to 1.9 was used. This ratio yielded a final free acidity of about 0.6 to 0.8M. As a result of Al3+ hydrolysis, it was possible to drive the A1-Am-Cm solution to about pH 10. However, acid concentrations less than 0.2M had to be avoided to prevent hydrolysis and precipitation of the actinides. 

Fig.2 shows the flow sheet of the HAW processing. The use of the waste solution directly for separation leads to the dissipation of avery large part of the electric energy for the electrolytic transport of the hydrogen and nitrate ions. The concentration of the nitric acid is therefore reduced to about 0.05 M through denitration by means of formic acid. To prevent the hydrolysis and the precipitation of some components, particularly Pu, acetic acid is added as complexing agent to the solution before denitration. The elements Nb,... 

Methylation of free OH groups, followed by denitration, hydrolysis, reduction, and glc analysis has been suggested as a method for determining the location of nitrate (82). This method has been suggested for CP and CS (82) as the phosphate and sulfate groups are stable to methylation and can then be removed. Periodate oxidation has been used to determine the DS of CS (81). 

In an alternative method of preparing m/vo-dihydroxyanthraquinonedisulfonic acid by heating the title compound with oleum to effect simultaneous hydrolysis, denitration and sulfonation of the nucleus, there is the possibility of formation of methyl nitrate from the scission fragments. 

The in vivo metabolism of nitrovasodilators, as exemplified above, can result from a number of pathways and mechanisms. The obvious pathways that come to mind first are enzymatic and nonenzymatic hydrolysis. As discussed below, the former pathway does not appear to occur, while the latter should play a limited role in vivo. The two other pathways to be discussed are hemoprotein-catalyzed and thiol-mediated reductive denitrations. 

Herzog and Londberg [20] have examined the X-ray diagrams of cellulose produced by denitration of a carefully nitrated product. The picture of the regenerated cellulose was in principle identical with that of cellulose before nitration. This observation suggests that a cautious nitration of cellulose that proceeds without oxidation or hydrolysis does not change the microcrystalline structure of the cellulose, i.e. this is a topochemical reaction, in which the product preserves the same... 

Croce and Okamoto [109] described a cationic micellar catalysis (Chapter IV) of aqueous alkaline hydrolysis of cyclonite (and octogene). Denitration occurred in the presence of ethylhexadecyldimethylammonium bromide. Liquid chromatography was used as the analytical method (32) ... 

Alkaline hydrolysis of starch nitrate produced ammonia, cyanides, nitrites, and nitrates.1478 Starch nitrate could be denitrated by use of diluted solutions of ammonium sulfite followed by the addition of hydrogen peroxide to remove colloidal sulfur.1448 The strong nitrate band absorption in the infrared between 730 and 960 cm-1 complicates the identification of polysaccharides. The region suitable for identification of starch nitrates is between 900 and 1350 cm M479 Nitration of glyceryl starch into a trinitrate was also reported.1480 Starch nitrates readily react with an TV.TV-dimethylformamidc-SO complex to give trisulfates.1481... 

The chemical stability of diethylene glycol dinitrate is roughly equal to nitroglycerine. Its hydrolysis is very slow even under hot water. For example, only 0.003 % diethylene glycol dinitrate is hydrolyzed at 60 °C for 120 h. It will be decomposed by waste acids. The denitration rate of diethylene glycol dinitrate in flie mixed acid with 7.5-10.5 % HNO3 and 0.5-1.1 % H2O is shown in Fig. 5.10. 

Danishefsky also investigated the development of a trans Diels-Alder reaction in seeming violation of the inherent stereoselectivity of the reaction mechanism. The key to this process was the use of 1-nitrocyclohexene (80) as the dienophile. After a standard intermolecular Diels-Alder reaction with diene 79, cis cycloadduct 81 could be transformed preferentially into trans-fused product 82 upon radical denitration and enol ether hydrolysis. ... 

Denitration can be achieved by strong sulfuric acid, but depolymerization of the carbohydrate also occurs. Alkaline hydrolysis gives rise to a mixture of polysaccharide fragmentation products as well as inorganic nitrates and nitrites. Nitrate groups are removed without appreciable degradation... 

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