Temperature dependence products with nitrate

Solutions of nitric acid in chlorinated solvents can add to some alkenes to give nitrate esters. Some tertiary nitrate esters can be prepared in this way isobutylene (49) reacts with fuming nitric acid of 98.6 % concentration in methylene chloride to give ferf-butyl nitrate (50). However, the products obtained depend on both the substrate and the reaction conditions /3-nitro-nitrate esters, vic-dinitrate esters, /3-nitroalcohols and nitroalkenes have been reported as products with other alkenes. Oxidation products like carboxylic acids are also common, especially at elevated temperatures and in the presence of oxygen. The reaction of alkenes with fuming nitric acid is an important route to unsaturated nitrosteroids, which assumedly arise from the dehydration of /3-nitroalcohols or the elimination of nitric acid from /3-nitro-nitrate... 

Quinoline-l-oxide undergoes nitration at the 2-, 5-, and 8-positions. While it is known that isomer ratios are temperature dependent, it has been recently shown that the orientation of nitration is also dependent on the acidity of the reaction medium <1997CPB279>. 2-Nitroquinoline 1-oxide, arising from nitration of unprotonated substrate, predominates under weakly acidic conditions. Nitration in stronger acidic media occurs on the hydroxyquinolinium ion and yields 5- and 8-nitroquinoline 1-oxide as the major products with increasing amounts of the 5-isomer formed in very highly acidic media. 

During World War II several authors resumed the investigations. G. B. Bachman and his co-workers [40] nitrated polystyrene with nitric acid (sp. gr. 1.50) and obtained products of various degrees of nitration depending on the nitration temperature at 50°C a product containing 10.0% of N was obtained, while at 150°C the product contained 11.2% of N. 

This has been demonstrated by the synthesis of several diastereomers, including A- and A-cis(N02),frans(NHCo(N02)2(S-aigH)2] + as the nitrate salts.4 The analogous A isomer as the chloride salt is synthesized herein. The applicability of this product to complex resolutions is shown by the resolution of ct s(N02),/rans(N)-[Cogly2(N02)2]- into diastereomers with the A-cis(N02),/ra/w(N)-[Co(N02)2(S-argH)2]+ion and by the partial resolution of [Co(acac)3] on a column of the optically active chloride salt. The A isomer can also be obtained through fractional crystallization, but the temperature dependence precludes the routine synthesis of both isomers without repeated recrystallizations. 

The products of these reactions are carbocations or olefins which are in equilibrium with the carbocations. Mechanisms involving structures VIII-13-VIII-14 can be only hardly discriminated. The only evidence for the mechanism of electrophilic substitution might be the deep similarity in selectivity and KIE for the reactions between palladium(ll) and alkanes on the one hand, and nitration of alkanes with NOz on the other hand. Indeed, such a similarity has been evaluated in the study of the temperature dependencies of KIE and 5/6 effects. 

Note that the concentration product of nitric acid and ammonia in equilibrium with a mixed sulfate-nitrate solution having a value of T = 0.5 is about one-half as high as that in equilibrium with a pure ammonium nitrate solution. The temperature dependence of the partial-pressure product for the aqueous mixed-salt case is similar to that of the pure salt. 

The reactions (Equation 3.72-73) cannot be the initiating factors of hydroperoxide decomposition. The reaction (Equation 3.72) is exothermic, but its stable products are nitrites and alcohols. However, the products of PP hydroperoxide conversion in an atmosphere of NO consist predominantly of macromolecular nitrates. The reaction (Equation 3.73) is strongly endothermic and, hence, unlikely to proceed at room temperature. Dependence of the induction period on the degree of purity of NO indicates that reactions involving trace amounts of higher nitrogen oxides control the initiation process. Consequently, the interaction of hydroperoxide with NO proceeds according to the reaction ... 

Control of exudation depends mainly on the suitable choice of the nitrocellulose used. Some lack of uniformity in this product is certainly desirable. This offers no serious difficulty, although it is necessary to ensure a constant watch on manufacturing processes to see that quality is maintained. In other gelatine explosives, particularly those containing ammonium nitrate, exudation can be induced by slow chemical reaction. The addition of alkalis, for example, can liberate ammonia which in turn can react with nitrocellulose and cause it to lose its power of binding nitroglycerine. Such effects are accelerated at high temperatures and under wet conditions and it is usual practice to test all explosives under such adverse conditions before they are put on the market. 

While nitramines are formed from the reaction of secondary amines with nitronium salts the success of the reaction depends on the basicity of the amine (Equation 5.11). Thus, amines of low to moderate basicity are A-nitrated in good yields. The nitration of more basic amines is slow and the nitrosamine is often observed as a significant by-product, a consequence of the partial reduction of the nitronium salt to the nitrosonium salt during the reaction. Increased reaction temperature is also found to increase the amount of nitrosamine formed. The amine substrate is usually used in excess to compensate for the release of the strong mineral acid formed during the reactions. Both nitronium tetrafluoroborate and the more soluble hexafluorophosphate are commonly used for A-nitrations. Solvents like acetonitrile, methylene chloride, nitromethane, dioxane, sulfolane, ethyl acetate and esters of phosphoric acid are commonly used. 

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