Sulphuric acid, action

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. 

The sulphonic acids are usually prepared by the action of sulphuric acid upon a compound. The concentration of the acid and the temperature of reaction are varied according to the reactivity of the compound. Often oleum is used or even chiorosulphonic acid. Alternatively sulphur trioxide complexed to pyridine or dioxan can be used with reactive substrates. Aminosulphonic acids such as sulphanilic and naphthionic acids are most conveniently prepared by heating the sulphate of the amine at ISO C. 

Strong oxidising acids, for example hot concentrated sulphuric acid and nitric acid, attack finely divided boron to give boric acid H3CO3. The metallic elements behave much as expected, the metal being oxidised whilst the acid is reduced. Bulk aluminium, however, is rendered passive by both dilute and concentrated nitric acid and no action occurs the passivity is due to the formation of an impervious oxide layer. Finely divided aluminium does dissolve slowly when heated in concentrated nitric acid. 

The hydrogen fluoride is conveniently produced in situ by the action of concentrated sulphuric acid on calcium fluoride ... 

Hydrochloric and dilute sulphuric acids have no appreciable action at room temperature on the pure Group V elements. 

Ammonia may be estimated by dissolving the gas in a known volume of standard acid and then back-titrating the excess acid. In a method widely used for the determination of basic nitrogen in organic substances (the Kjeldahl method), the nitrogenous material is converted into ammonium sulphate by heating with concentrated sulphuric acid. The ammonia is then driven off by the action of alkali and absorbed in standard acid. 

It is the nitronium ion which is responsible for nitrating actions in organic chemistry which are carried out in a mixture of nitric and sulphuric acids. When nitric acid is dissolved in water, its behaviour is that of a strong acid, i.e. ... 

By their oxidising action heating with copper and concen trated sulphuric acid yields brown fumes of nitrogen dioxide. 

Industrially. phosphoric(V) acid is manufactured by two processes. In one process phosphorus is burned in air and the phos-phorus(V) oxide produced is dissolved in water. It is also manufactured by the action of dilute sulphuric acid on bone-ash or phosphorite, i.e. calcium tetraoxophosphate(V). Ca3(P04)2 the insoluble calcium sulphate is filtered off and the remaining solution concentrated. In this reaction, the calcium phosphate may be treated to convert it to the more soluble dihydrogenphosphatc. CafHjPOjj. When mixed with the calcium sulphate this is used as a fertiliser under the name "superphosphate . 

Ozone is formed in certain chemical reactions, including the action of fluorine on water (p. 323) and the thermal decomposition ofiodic(VII) (periodic) acid. It is also formed when dilute (about 1 M) sulphuric acid is electrolysed at high current density at low temperatures the oxygen evolved at the anode can contain as much as 30% ozone. 

The reducing action of sulphurous acid and sulphites in solution leads to their use as mild bleaching agents (for example magenta and some natural dyes, such as indigo, and the yellow dye in wool and straw are bleached). They are also used as a preservative for fruit and other foodstuffs for this reason. Other uses are to remove chlorine from fabrics after bleaching and in photography. 

Hydrogen bromide cannot be prepared readily by the action of sulphuric acid on a bromide, because the latter is too easily oxidised by the sulphuric acid to form bromine. It is therefore obtained by... 

The action of concentrated sulphuric acid liberates hydrogen fluoride, which attacks glass, forming silicon tetrafluoride the latter is hydrolysed to silicic acid by water, which therefore becomes turbid,... 

Nitriles also react w ith Grignard reagents to give ketones, which arise from the hydrolysing action of the dilute sulphuric acid on the intermediate addition product. Acid amides beha e similarly. 

Concentrated sulphuric acid. The only well-known use for this reagent is for drying bromine, with which it is immiscible. The bromine is shaken in a separatory funnel with small quantities of concentrated sulphuric acid until no further action takes place. The reagent is, however, widely used for desiccators. 

Nitrations are usually carried out at comparatively low temperatures at higher temperatures there may be loss of material because of the oxidising action of the nitric acid. For substances which do not nitrate readily with a mixture of concentrated nitric and sulphuric acids ( mixed acid ), the intensity of the reaction may be increased inler alia by the use of fuming sulphuric acid (containing up to 60 per cent, of sulphur trioxide) or by fuming nitric acid. Thus nitrobenzene is converted by a mixture of fuming nitric acid and concentrated sulphuric acid into about 90 per cent, of wi-dinitrobenzene and small amounts of the o- and p-isomers the latter are eliminated in the process of recrystallisation ... 

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 ... 

The action of sulphuric acid alone upon acetone cyanohydrin affords a-methylacrylic acid. The methyl methacrylate polymers are the nearest approach to an organic glass so far developed, and are marketed as Perspex (sheet or rod) or Dialcon (powder) in Great Britain and as Plexiglass and Luciie in the U.S.A. They are readily depolymerised to the monomers upon distillation. The constitution of methyl methacrylate polymer has been given as ... 

Hydrolysis of a nitrile to an amide. Warm a solution of 1 g. of the nitrile benzyl cyanide) in 4 ml. of concentrated sulphuric acid to 80-90°, and allow the solution to stand for 5 minutes. Cool and pour the solution cautiously into 40 ml. of cold water. Filter oflT the precipitate stir it with 20 ml. of cold 5 per cent, sodium hydroxide solution and filter again. RecrystaUise the amide from dilute alcohol, and determine its m.p. Examine the solubility behaviour and also the action of warm sodium hydroxide solution upon the amide. 

Therefore, in the cases of both additives, the kinetic law for the catalysis will assume a linear form when the concentration of the added species, or, in the case of sulphuric acid, the nitronium ion generated by its action, is comparable with the concentration of the species already present. This effect was observed to occur when the concentration of additive was about o-2 mol 1, a value in fair agreement with the estimated degree of dissociation of nitric acid ( 2.2.1). 

S-Coniceine (2-piperolidine), is prepared by the action of sulphuric acid on bromoconiine. It has a multiplicity of names. Itw, s first characterised by Lellmann, who assigned to it formula (III) and was synthesised by Loffler and Kaim who distilled piperidylpropionic acid to obtain piperolid-2-one (IV) and reduced this to 2-piperolidine (III) which proved... 

Seheuing and Winterhalder treated 2 6-distr3rrylpyridine tetra-bromide with potassium hydroxide in alcohol, so producing 2 6-di-)3-phenylacetylenylpyridine (XI) which by the action of 50 per cent, sulphuric acid was converted into 2 6-diphenacylpyridine (XII), and this, on hydrogenation in presence of platinic oxide, barium sulphate and methyl alcohol, was reduced to 2 6-di-(6-hydroxy-(6-phenylethylpyridine, and the hydrochloride of this, on similar catalytic hydrogenation, yielded worlobelanidine (XIII). This can be methylated to lobelanidine, from which in turn dMobeline and lobelanine can be obtained. 

The nature of the investigation of the action of bromine on nicotine (Formula A),. So treated in acetic acid nicotine yielded a hydrobromide perbromide, C oHjjONgBr,. HBr. Br, from -which, after treatment with aqueous sulphurous acid, the free base, dibromocotinine (Formula D), C QH jONjErj,... 

Meconidine, C21H23O4N. This alkaloid was prepared by Hesse and its existence in Japanese opium was confirmed by Machiguchi. It is a brownish-yellow, amorphous substance, m.p. 58°, easily soluble in alcobol, most organic solvents and in alkalis. It gives a green solution with sulphuric acid. The salts are amorphous. Meconidine is said to exhibit a slight tetanising action. 

Oxyberberine, C2oHj,05N, This, the first product of the action of potassium permanganate on berberine, crystallises from xylene in plates, m.p. 198-200°. When even traces are dissolved in 50 per cent, sulphuric acid and a drop of nitric acid is added, a brown colour is produced, changing to intense violet. The constitution of oxyberberine is discussed below. From the results of these and other reactions, Perkin assigned a formula to berberine, which was modified by Perkin and Robinson to(V). 

In the cases of quinine and quinidine there is an additional complication, except for reaction (c), owing to partial de-methylation of the methoxyl group, thus in the action of sulphuric acid on quinine there may be four products of formula E, viz., the two geometrical isomerides apoquinine and isoapoquinine (for which Q is 6-hydroxyquinolyl) and their methyl ethers, j8-isoquinine and a-isoquinine respectively (for which Q is 6-methoxyquinolyl). 

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