Sulphuric acid, action 70%, preparation

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. 

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... 

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 ... 

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... 

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. 

Camphene is prepared artificially by the isomerisation of pinene with sulphuric acid or by the withdrawal of HCl from pinene monohydrochloride, or by the action of heat in the presence of acetic anhydride on bornylamine, CjjHj7NH2, which causes the withdrawal of ammonia and leaves camphene, as follows —... 

The latest patent for the preparation of artificial thymol is that of E. M. Cole (U.S.P. 1,378,939, 24 May, 1921). His method consists essentially in the electrolytic reduction of nitro-cymene in the presence of sulphuric acid, and the subsequent diazotisation and reduction of the para-amidocymenol produced, by e ctric action, involving the use of stannous chloride. 

Hydrochloric acid and sulphuric acid are widely employed in the preparation of standard solutions of acids. Both of these are commercially available as concentrated solutions concentrated hydrochloric acid is about 10.5- 12M, and concentrated sulphuric acid is about 18M. By suitable dilution, solutions of any desired approximate concentration may be readily prepared. Hydrochloric acid is generally preferred, since most chlorides are soluble in water. Sulphuric acid forms insoluble salts with calcium and barium hydroxides for titration of hot liquids or for determinations which require boiling for some time with excess of acid, standard sulphuric acid is, however, preferable. Nitric acid is rarely employed, because it almost invariably contains a little nitrous acid, which has a destructive action upon many indicators. 

Hydrogen does not appear free in the atmosphere except at levels below 1 ppm, since rapid diffusivity enables molecules to escape the earth s gravitational field and it is continuously lost from the atmosphere. It is present in the earth s crust at about 0.87% in combination with oxygen in water and with carbon and other elements in organic substances. It is prepared commercially on a small scale by action of sulphuric acid on zinc ... 

Ethyl and 2-fluoroethyl 9-bromononanecarboxylate and ethyl and 2-fluoroethyl 9-fluorononanecarboxylate were all prepared from 9-bromononanecarboxylic acid, made by the action of hydrogen bromide and sulphuric acid on 9-acetoxynonane-carboxylic acid, which in turn was obtained by a four-stage synthesis from sebacic acid. 

The reaction just described is carried out technically on a large scale in iron vessels provided with stirrers, for /9-naphthol, as well as the numerous sulphonic acids which can be obtained from it by the action of sulphuric acid, is widely used for the preparation of azo-dyes. Moreover, by the action of ammonia under pressure, /3-naphthylamine is produced from /S-naphthol ... 

Preparation.—1. In the pure state by the action of sulphuric acid on an alloy of arsenic and sine —... 

Dichloro-tetrammino-platinic Chloride, [Pt(NH8)4Cl2]Cl2, is prepared by passing chlorine gas through a solution of tetrammino-platinous chloride till the liquid begins to turn red. From the cold dilute solution the salt crystallises with one molecule of water of crystallisation, whilst from more concentrated solutions the anhydrous salt is deposited. It may also be obtained by the action of ammonia on tetraehloro-dianunino-platinum. It crystallises in pale yellow microscopic oetahedra, is sparingly soluble in water, and only half of the chlorine is precipitated as silver chloride when the aqueous solution is treated with a cold solution of silver nitrate. Sulphuric acid eliminates only two molecules of chlorine.1... 

According to E. Fremy s Recherches sur les fluorures (1856), the acid furnished by the action of sulphuric acid on fluorspar always contains water, sulphuric acid, sulphurous acid, hydrofluosilicic acid, and other impurities. After many fruitless attempts to puiify and dehydrate the crude material so obtained, he sought other means of preparation, and found that anhydrous hydrofluoric acid could be satisfactorily obtained by heating well-dried potassium hydrogen fluoride in a platinum retort attached to a platinum receiver which was cooled by immersion in a freezing mixture. The first portions of the acid which distilled over contained a little moisture. H. Moissan thus describes the operation ... 

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