Sulphonic acids acidity

Hydroxylamine. Hydroxynitrilomono Hydroxynitrilodisulphonic Hydroxynltrilotrisulphonic sulphonic acid. acid. add. 

Curing temperatures below 120°C are obtained by additions of acids, such as para-toluene sulphonic acid, acid butyl phosphate, acid butyl maleate or special proprietory catalysts. The combination of acid catalysis and a highly reactive melamine formaldehyde resin can result in curing temperatures as low as 80°C. In such cases the paint formulator must pay careful attention to pigment and viscosity stabilities to ensure that flocculation of the pigment does not occur. Viscosity is normally controlled by primary alcohols in the solvent blend (at least 20% of total solvent). 

Dissolves in alkaline solutions to give purple-red solutions which are precipitated as lakes by heavy metal salts. Occurs naturally as a glucoside in madder but produced synthetically by fusing anthraquinone-2-sulphonic acid with NaOH and some KCIO3. Applied to the mordanted fibre. Al(OH)3 gives a bright red lake, Cr(OH)3 a red lake, FefOH) ... 

C. A typical aromatic amine. Best prepared by the prolonged action of concentrated ammonia solution at a high temperature upon anthraquinone-l-sulphonic acid in the presence of BaClj and by reduction of the corresponding nitro compound or by amination of the chloroanthraquinone. 

Anthraquinone can be brominated, chlorinated directly to the tetrachloro (I, 4, 5, 8-) stage, nitrated easily in the 1-position, but gives the 1,5-and 1,8-dinitro-derivalives on prolonged nitration the nitro groups in these compounds are easily displaced by neutral solutions of alkali sulphites yielding the corresponding sulphonic acids. Sulphonation with 20-30 % oleum gives the 2- 2,6- and 2,7-derivatives in the presence of Hg the 1- 1,5- and 1,8- derivatives are formed. 

Anthraquinone-J -sulphonic acid. Colourless leaflets, m.p. 214 C. It is used in the preparation of l-aminoanthraquinone. 

Ordinary commercial camphor is (-i-)-cam phor, from the wood of the camphor tree. Cinnamonum camphora. Camphor is of great technical importance, being used in the manufacture of celluloid and explosives, and for medical purposes, /t is manufactured from pinene through bornyl chloride to camphene, which is either directly oxidized to camphor or is hydrated to isoborneol, which is then oxidized to camphor. A large number of camphor derivatives have been prepared, including halogen, nitro and hydroxy derivatives and sulphonic acids. 

Usually prepared from the corresponding sulphonic acids by alkali fusion, methylation of phenol or from the aminotoluene by treatment with nitrous acid followed by boiling. Both o- and p-cresol are used as end components in azo dyes. 

Naphthalene-1-sulphonic acid crystallizes with 2HiO, m.p. 90 C. Used for the preparation of 1,8- and 1,5-nitronaphlhalene sulphonic acids. 

Naphihalene-2-sulphonic acid crystallizes with 3H2O, m.p. 83 C. It is also used for the preparation of nitro-derivatives. 

Naphthalene (risulphonic acids can be obtained by more drastic sulphonation of naphthalene or its mono- and disulphonic acids. Only the 1,3,5-, 1,3,6- and 1,3,7-acids are obtained. The most important of the iri-sulphonic acids is the 1,3,6-acid which is used for the preparation of H-acid, a dyestufT intermediate. 

Neville-Wintber acid The trivial name given to 4-hydroxy-1-naphthalene sulphonic acid. 

Further nitration gives w-dinilrobenzene sulphonation gives w-nitrobenzene sulphonic acid. Reduction gives first azoxybenzene, then azobenzene and aniline depending upon the conditions. Used in the dyestufTs industry as such or as aniline. 

Perfluoroalkyl derivatives have important technical uses, e.g. sulphonic acids as surfactants introduction of perfluoroalkyl groups confers useful properties on many drugs. 

Phenylhydrazine condenses with acetoacetic ester to give a pyrazolone derivative which on methylation gives phenazone. The sulphonic acid similarly gives rise to the tartrazine dyestuffs. It is used to make indole derivatives by the Fischer process. 

Schaffer s acid, CioHg04S. 2-hydroxy-7-naphthalene sulphonic acid. Obtained by sulphonating 2-naphthol with a small amount of sulphuric acid at a higher temperature than is used for the preparation of crocein acid. A valuable dyestuff intermediate. 

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. 

The sulphonic acids are strongly acidic compounds, very soluble in water and readily give water-soluble metallic salts. 

The most important reaction of the sulphonic acids is their conversion into phenols by fusion with caustic alkalis. When they are fused with potassium cyanide, nitriles are obtained, e.g. benzonitriie from ben-zenesulphonic acid. 

CaH803. Fine white needles, m.p. 82°C, b.p. 285°C, strong vanilla odour, characteristic taste. It occurs extensively in nature, and is the odoriferous principle of the vanilla pod it can be obtained from the glucoside coniferin. Vanillin is made commercially from the ligno-sulphonic acid obtained as a by-product in the manufacture of wood pulp. It is one of the most important flavouring and perfuming... 

Aromatic nitriles (or aryl cyanides) can be obtained by methods (1) and (3). but not by method (2). In addition, aromatic nitriles can be prepared by two other methods, (a) from the corresponding diazo compound by Sandmeyer s Reaction (p. 189), (b) by fusing the corresponding sulphonic acid (or its salts)... 

If phenol is heated with more concentrated nitric add (in the presence of sulphuric acid), nitration occurs ultimately at the para and at both the ortho positions, giving picric acid or 2,4,6-trinitrophenol. To prepare picric acid, however, it is more convenient first to heat the phenol with sulphuric acid, whereby a mixture of 0- and p-phenol sulphonic acids is readily obtained. If this mixture is now heated with concentrated nitric acid, nitration occurs at the... 

Aromatic sulphonic acids are frequently difficult to obtain pure, since they almost invariably decompose on attempted distillation, and many are very soluble in water such aqueous solutions on being concentrated often give syrupy solutions from which the sulphonic acid crystallises with difficulty. 

Toluene however sulphonates readily, and the following preparation illustrates the rapid formation of toluene-p ulphonic acid mixed with a small proportion of the deliquescent o-sulphonic acid, and the isolation of the pure crystalline /lara-isomer. 

This direct sulphonation should be compared with the indirect methods for the preparation of aliphatic sulphonic acids, e.g., oxidation of a thiol (RSH -> RSOjH), and interaction of an alkyl halide with sodium sulphite to give the sodium sulphonate (RBr + Na,SO, -> RSO,Na + NaBr). 

A further crystallisation from 15 ml. of hydrochloric acid gives the sulphonic acid, 5 5 g., m.p. 105°, almost devoid of deliquescent properties. 

The Schotten-Baumann reaction may also be carried out, using, for example, benzene sulphonyl chloride, CeH,SO,Cl (. e., the acid chloride of benzene sulphonic acid, C H5SOjOH) in place of benzoyl chloride, and similar deri a-tives are obtained. Thus when phenol is dissolved in an excess of 10% sodium hydroxide solution, and then shaken with a small excess of benzene sulphonyl... 

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