Nitric acid function

The actual mechanism by which the N=N molecule cleaves is very complicated, and is not fully understood yet. It is nevertheless clear that much nitrogen is oxidized to form nitrous oxide, NO. This NO dissolves in the water that inevitably accompanies lightning and forms water-soluble nitrous acid HNO2, which further oxidizes during the storm to form nitric acid, HNO3. Nitric acid functions as a high-quality fertilizer. It has been estimated that a thunderstorm can yield many tonnes of fertilizer per acre of land. 

This reaction proceeds via an electrophilic aromatic subsdtudon in which a nitronium ion (NO2 ) is believed to be the electrophile. This strong electrophile is formed from the acid-base reaction that takes place between HNO3 and H2SO4. Nitric add functions as a base to accept a proton from sulfuric acid, followed by loss of water to produce a nitronium ion (Mechanism 19.5). It might seem strange that nitric acid functions as a base rather than an add, but remember that acidity... 

The function of the sulphuric acid is to furnish a strongly acid medium and to convert the nitric acid into the highly reactive nitronium ion NOj+, which is the real nitrating agent ... 

Acidity function plots have been used in another way. In 65-90 % sulphuric acid the concentration of the nitronium ion is not equal to the concentration of nitric acid the quantity... 

The reaction of aldoses with nitric acid leads to the formation of aldaric acids by oxidation of both the aldehyde and the terminal primary alcohol function to carboxylic acid groups Aldaric acids are also known as saccharic acids and are named by substi tutmg aric acid for the ose ending of the corresponding carbohydrate... 

These variations permit the separation of other components, if desired. Additional data on uranium, plutonium, and nitric acid distribution coefficients as a function of TBP concentration, solvent saturation, and salting strength are available (24,25). Algorithms have also been developed for the prediction of fission product distributions in the PUREX process (23). 

A mathematical model of the operating characteristics of a modem HLW storage tank has been developed (60). This model correlates experimental data for the rate of radiolytic destmction of nitric acid, the rate of hydrogen generation owing to radiolysis of water, and cooling coil heat transfer. These are all functions of nitric acid concentration and air-lift circulator operation. 

Aldaric acid (Section 25.19) Carbohydrate in which carboxylic acid functions are present at both ends of the chain. Aldaric acids are typically prepared by oxidation of aldoses with nitric acid. 

Similar to the alkylation and the chlorination of benzene, the nitration reaction is an electrophilic substitution of a benzene hydrogen (a proton) with a nitronium ion (NO ). The liquid-phase reaction occurs in presence of both concentrated nitric and sulfuric acids at approximately 50°C. Concentrated sulfuric acid has two functions it reacts with nitric acid to form the nitronium ion, and it absorbs the water formed during the reaction, which shifts the equilibrium to the formation of nitrobenzene ... 

The nitrate ion of the nitric acid acts as the oxidizing agent. The function of the hydrochloric add is to furnish Cl ions to form the very stable complex ion Audi. ... 

An important aspect of nitrating toluene to nitrotoluene is the very low solubility of toluene and nitroioluenes in nitrating mix Is. Therefore the nitration proceeds in a two-phase system and the rate of nitration depends greatly on dispersion, which in turn depends on keeping the two phases efficiently stirred. This is emphasized in Fig 4, which gives the yield of MNT for a 11/64/25% nitric acid/sulfuric acid/water MA and a nitration time of 30 minutes as a function of stirring speed... 

Fig 5 shows the yield of MNT as a function of acid/toluene ratio for a MA of 27/55/18% nitric acid/sulfuric acid/water and a nitration time of 50 minutes at 30°... 

The heat capacities of liq gaseous nitric acid may be expressed as functions of the absolute temp, T, by Eqs 1 2 (according to Lagowski, Ref 32, p 153)... 

The conclusion that the nitration of quinoline in sulphuric acid takes place via the conjugate acid has been confirmed by Moodie et al.50, who measured the rates of nitration of a wide range of heterocyclic compounds in nitric acid-sulphuric acid mixtures at a range of temperatures. A summary of the second-order rate coefficients and Arrhenius parameters is given in Table 4. From an analysis of the shapes of the plots of log k2 versus sulphuric acid acidity (or some function of this), it was concluded that all of the compounds starred in Table 4... 

Finally, it is customary to compare the partial rate factors obtained under different conditions to indicate the reactivity of the electrophile. Unfortunately, the medium, nitric acid in sulphuric acid, in which the nitronium ion is most clearly established as the electrophile, is such a poor solvent for aromatics that meaningful competitive nitrations are impossible and kinetic studies are hampered by the difficulties noted above. However, since the isomer distribution is a function of the rate factors, inspection of these distributions (Table 15) shows a very... 

Nonaqueous Systems In nonaqueous (nonpolar) solvent systems, nitrosatlon also proceeds. In these solvents, alpha-tocopherol acts as a lipid soluble blocking agent in much the same fashion as ascorbic acid functions in the aqueous phase. Alpha-tocopherol reacts with a nitrosating agent and reduces it to nitric oxide. At the same time, alpha-tocopherol is oxidized to tocoquinone, which is the first oxidation product of vitamin E and also a normal metabolite in vivo. 

J(PQ) and J(PN)). Trends in J(P170) have been used to study the protonation of phosphoryl tribromide, phosphoryl trifluoride and dif1uorophosphoric acid. Nitric acid had a greater protonation power than Hammett acidity functions indicated.77 This coupling has been the subject of a semiempirical sum over states theoretical study.7 ... 

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