sulphonation

When these insoluble azo colours are treated with sulphuric acid they are converted into sulpho acids, undergoing what is called sulphonation, an operation of the greatest (p. 067) importance and value in the preparation of dye-stuffs.

The Dyeing of Woollen Fabrics Franklin Beech

Complete solution of the substance in sulphuric acid is, generally speaking, a criterion of complete sulphonation.

Synthetic Tannins Georg Grasser

CO. O.C_6H_5 is sulphonated, a product is obtained which is easily soluble in water, but which is identified as a mixture of the sulphonation products of salicylic acid and phenol, the salol being dissociated on sulphonation.

Synthetic Tannins Georg Grasser

It makes no difference to the final product whether the condensation is the first step followed by sulphonation and consequent solubilisation of the intermediary insoluble product, or whether, vice versa, the sulphonic acid is subjected to condensation.

Synthetic Tannins Georg Grasser

Of aromatic acids all those which yield water-soluble sulphonation products seem suitable for the industrial production of tanning matters.

Synthetic Tannins Georg Grasser

(CH_3) _2 is sulphonated, and the water-soluble sulphonation product heated with formaldehyde for some time, the product remains soluble in water and precipitates gelatine.

Synthetic Tannins Georg Grasser

If the acids themselves do not yield water-soluble sulphonation products, the alkali salts of the latter may be condensed with formaldehyde, and the resulting products then constitute tanning matters provided their solutions can be neutralised or faintly acidified without the solute being thrown out of solution in insoluble form.

Synthetic Tannins Georg Grasser

A very similar condensation product was obtained by condensing sodium-_p_-hydroxybenzoate with formaldehyde and subsequent sulphonation with sulphuric acid.

Synthetic Tannins Georg Grasser

In addition to phenolic mono - and disulphonic acids (and higher sulphonation compounds), the homologues, cresols, xylenols, and naphthols enter into reaction.

Synthetic Tannins Georg Grasser

OH. COOH. which at higher temperatures is easily sulphonated with concentrated sulphuric acid; the sulphonation product represents a white solid, which easily dissolves in water forming a clear liquid.

Synthetic Tannins Georg Grasser