Nitric acid compounds

Under the influence of acetic anhydride and nitric acid compound (XXX) gives (XXV) (Marcus and Winkler [68]). 

Intercalation compounds of graphite with perfluoroalkanesulfonic acids and alkane sulfonic acids occur . Phase transitions occur in graphite-nitric acid compounds ". ... 

At room temperature, the intercalated layers of a stage two nitric acid compound are disordered in a liquid-like state modulated by the graphite lattice. The intercalated nitric acid molecules are neither organized in double layers, as suggested earlier by Rudorff , nor oriented parallel to the graphite c axis. Instead, the molecule planes are tilted by about 30° to the c axis, as deduced from neutron spectroscopy and from X-ray data". 

Compound A is a D-aldopentose. When treated with sodium borohydride, compound A is converted into an alditol that exhibits three signals in its C NMR spectrum. Compound A undergoes a Kiliani-Fischer synthesis to produce two aldo-hexoses, compounds B and C. Upon treatment with nitric acid, compound B yields compound D, while compound C yields compound E. Both D and E are optically active aldaric acids. 

Carius method The quantitative determination of S and halogens in covalent (organic) compounds by complete oxidation of the compound with cone, nitric acid and subsequent estimation of precipitated AgX or BaS04. 

CCls CHO. A colourless oily liquid with a pungent odour b.p. 98°C. Manut actured by the action of chlorine on ethanol it is also made by the chlorination of ethanal. When allowed to stand, it changes slowly to a white solid. Addition compounds are formed with water see chloral hydrate), ammonia, sodium hydrogen sulphite, alcohols, and some amines and amides. Oxidized by nitric acid to tri-chloroethanoic acid. Decomposed by alkalis to chloroform and a methanoate a convenient method of obtaining pure CHCI3. It is used for the manufacture of DDT. It is also used as a hypnotic. 

Nitro-compounds are prepared by the direct action of nitric acid. The reaction is greatly facilitated if a mixture of nitric and sulphuric acid is used. 

Uses of ammonia and ammonium compounds. Most of the ammonia produced is used in the manufaeture of nitrogenous fertilisers such as ammonium sulphate. Other uses include nitric acid and synthetic fibre and plastic manufacture. 

Oxidation of a sulphur compound with concentrated nitric acid yields sulphuric acid or a sulphate, which can be tested for with barium chloride. This can be used to estimate the sulphur. 

Certain aliphatic compounds are oxidised by concentrated nitric acid, the carbon atoms being split off in pairs, with the formation of oxalic acid. This disruptive oxidation is shown by many carbohydrates, e.g., cane sugar, where the chains of secondary alcohol groups, -CH(OH)-CH(OH)-CH(OH)CH(OH)-, present in the molecule break down particularly readily to give oxalic acid. 

It should be noted that aliphatic compounds (except the paraffins) are usually oxidised by concentrated nitric acid, whereas aromatic compounds (including the hydrocarbons) are usually nitrated by the concentrated acid (in the presence of sulphuric acid) and oxidised by the dilute acid. As an example of the latter, benzaldehyde, CjHsCHO, when treated with concentrated nitric acid gives ffi-nitrobenzaldehyde, N02CgH4CH0, but with dilute nitric acid gives benzoic acid, CgHgCOOH. 

If phenol is treated even with dilute nitric acid at room temperature, nitration readily occurs with the simultaneous formation of the yellow o-nitro-phenol and the white /> nitrophenol. These compounds can be readily... 

Selenium dioxide. The compound is conveniently prepared by the oxidation of selenium with nitric acid, followed by dehydration of the selenious acid thus formed by cautious heating ... 

Add 1 drop (0 05 ml.) of concentrated nitric acid to 2 0 ml. of a 0 5 per cent, aqueous solution of paraperiodic acid (HjIO,) contained in a small test-tube and shake well. Then introduce 1 op or a small crystal of the compound. Shake the mixture for 15 seconds and add 1-2 drops of 5 per cent, aqueous silver nitrate. The immediate production of a white precipitate (silver iodate) constitutes a positive test and indicates that the organic compound has been oxidised by the periodic acid. The test is based upon the fact that silver iodate is sparingly soluble in dilute nitric acid whereas silver periodate is very soluble if too much nitric acid is present, the silver iodate will not precipitate. 

However, if an oxidising agent (fuming nitric acid or sodium persulphate) is present to destroy the hydrogen iodide as it is formed, the equilibrium is displaced and the iodo compound may be conveniently prepared, for example ... 

Add 1 g. of the compound to 4 ml. of concentrated sulphuric acid and cautiously introduce, drop by drop, 4 ml. of fuming nitric acid. Warm the mixture on a water bath for 10 minutes, then pour it on to 25 g. of crushed ice (or 25 ml. of ice water). Collect the precipitate by filtration at the pump, and recrystallise it from dilute alcohol. 

Picric acid, the 2 4 6-trinitro derivative of phenol, cannot be prepared in good yield by the action of nitric acid upon phenol since much of the latter is destroyed by oxidation and resinous products are also formed. It is more convenient to heat the phenol with concentrated sulphuric acid whereby a mixture of o- and p-phenolsulphonic acids is obtained upon treatment of the mixture with concentrated nitric acid, nitration occurs at the two positicsis mela to the —SOjH group in each compound, and finally, since sulphonation is reversible, the acid groups are replaced by a third iiitro group yielding picric acid in both cases ... 

Reaction with alcoholic silver nitrate. To carry out the test, treat 2 ml. of a 2 per cent, solution of silver nitrate in alcohol with 1 or 2 drops (or 0 05 g.) of the compound. If no appreciable precipitate appears at the laboratory temperature, heat on a boiling water bath for several minutes. Some organic acids give insoluble silver salts, hence it is advisable to add 1 drop of dilute (5 per cent.) nitric acid at the conclusion of the test most silver salts of organic acids are soluble in nitric acid. 

In qualitative organic analysis, use is made of the fact that silver iodate is sparingly soluble in dilute nitric acid whereas silver periodate is very soluble. For water-insoluble compounds solutions in ethanol or in pure dioxan may be employed. 

Place 2 ml. of the periodic acid reagent in a small test tube, add one drop (no more—otherwise the silver iodate, if formed, will fail to precipitate) of concentrated nitric acid, and shake well. Add one drop or a small crystal of the compound to be tested, shake the mixture for 15-20 seconds, and then add 1-2 drops of 3 per cent, silver nitrate solution. The instantaneous formation of a white precipitate of silver iodate is a positive test. Failure to form a precipitate, or the appearance of a brown precipitate which redissolves on shaking, constitutes a negative test. 

During my Cleveland years, I also continued and extended my studies in nitration, which I started in the early 1950s in Hungary. Conventional nitration of aromatic compounds uses mixed acid (mixture of nitric acid and sulfuric acid). The water formed in the reaetion dilutes the acid, and spent aeid disposal is beeoming a serious environ-... 

Benzene and some of its derivatives react with solutions of mercuric nitrate in concentrated nitric acid to give nitrophenols. These reactions, known as oxynitrations may proceed by mercuration followed by nitroso-demercuration the resulting nitroso compound becomes a diazonium compound and then a phenol, which is nitrated. ... 

The operation of the nitronium ion in these media was later proved conclusively. "- The rates of nitration of 2-phenylethanesulphonate anion ([Aromatic] < c. 0-5 mol l i), toluene-(U-sulphonate anion, p-nitrophenol, A(-methyl-2,4-dinitroaniline and A(-methyl-iV,2,4-trinitro-aniline in aqueous solutions of nitric acid depend on the first power of the concentration of the aromatic. The dependence on acidity of the rate of 0-exchange between nitric acid and water was measured, " and formal first-order rate constants for oxygen exchange were defined by dividing the rates of exchange by the concentration of water. Comparison of these constants with the corresponding results for the reactions of the aromatic compounds yielded the scale of relative reactivities sho-wn in table 2.1. 

The values are precisely defined only for a given nitric acid concentration, as the dependence of rate on nitric acid concentration varies from one compound to another... 

A simple kinetic order for the nitration of aromatic compounds was first established by Martinsen for nitration in sulphuric acid (Martin-sen also first observed the occurrence of a maximum in the rate of nitration, occurrii for nitration in sulphuric acid of 89-90 % concentration). The rate of nitration of nitrobenzene was found to obey a second-order rate law, first order in the concentration of the aromatic and of nitric acid. The same law certainly holds (and in many cases was explicitly demonstrated) for the compounds listed in table 2.3. 

Although the proportion of nitric acid present as nitronium ions does not change between 90% and 100% sulphuric acid, the rate constants for nitration of most compounds decrease over this rai e. Fig. 2.1 illustrates the variation with acidity of the second-order rate constants of the nitration of a series of compounds of widely differing reactivities. Table 2.4 lists the results for nitration in 95% and 100% acid of a selection of less completely investigated compounds. 

There is increasing evidence that the ionisation of the organic indicators of the same type, and previously thought to behave similarly, depends to some degree on their specific structures, thereby diminishing the generality of the derived scales of acidity. In the present case, the assumption that nitric acid behaves like organic indicators must be open to doubt. However, the and /fp scales are so different, and the correspondence of the acidity-dependence of nitration with so much better than with Hg, that the effectiveness of the nitronium ion is firmly established. The relationship between rates of nitration and was subsequently shown to hold up to about 82 % sulphuric acid for nitrobenzene, />-chloronitrobenzene, phenyltrimethylammonium ion, and p-tolyltrimethylammonium ion, and for various other compounds. ... 

Data for zeroth-order nitration in these various solvents are given in table 3.1. Fig. 3.1 shows how zeroth-order rate constants depend on the concentration of nitric acid, and table 3.2 shows how the kinetic forms of nitration in organic solvents depend on the reactivities of the compounds being nitrated. 

The observation already discussed ( 2.2, 2.3, 2.4) of nitrations, in concentrated and aqueous mineral acids and in pure nitric acid, which depend on the first power of the concentration of the aromatic compound, does not help much in elucidating the mechanisms of nitrations under these conditions. In contrast, the observation of zeroth-order... 

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