Meta-aminophenol is prepared by reducing metanitrophenol, or by heating resorcin with ammonium chloride and ammonia to 200° C. Dimethyl-meta-aminophenol is prepared by heating meta-aminophenol with methyl alcohol and hydrochloric acid in an autoclave; by sulphonation of dimethylaniline, the sulphonic acid formed being finally fused with potash; or by nitrating dimethylaniline, in the presence of sulphuric acid at 0° C. In the latter case a mixture of nitro-compounds is obtained which can be separated by the addition of sodium carbonate.
Phenol dissolves readily in concentrated sulphuric acid, a mixture of phenol-orthoand -para-sulphonic acids being formed.
Oxidation of thio-ethers results in the formation of sulphoxides, R2: S: 0, and sulphones, R2: S02; oxidation of mercaptans yields sulphonic acids, R S0 3 H, and of sodium mercaptides sulphinic acids, R S0(OH).
For example: nitric acid and sulphuric acid readily react with benzene and its homologues with the production of nitro derivatives and sulphonic acids, while in the aliphatic series these acids exert no substituting action (in the case of the olefines, the latter acid forms an addition product); another distinction is that the benzene complex is more stable towards oxidizing agents.
This compound is readily oxidized to benzoic acid, C 6 H 5 000H, the aromatic residue being unattacked; nitric and sulphuric acids produce nitro-toluenes, C6H4 CH3 N02j and toluene sulphonic acids, C 6 H 4 CH 3 SO 3 H; chlorination may result in the formation of derivatives substituted either in the aromatic nucleus or in the side chain; the former substitution occurs most readily, chlor-toluenes, C 6 H 4 CH 3 Cl, being formed, while the latter, which needs an elevation in temperature or other auxiliary, yields benzyl chloride, C 6 H 5 CH 2 C1, and benzal chloride, C 6 11 5 CHC1 2.
Experience has shown that such mono-derivatives as nitro compounds, sulphonic acids, carboxylic acids, aldehydes, and ketones yield as a general rule chiefly the meta-compounds, and this is independent of the nature of the second group introduced; on the other hand, benzene haloids, amino-, homologous-, and hydroxy-benzenes yield principally a mixture of the orthoand para-compounds.
Ethyl salicylate, C 6 H 4 (OH) CO 2 C 2 H 5j is obtained by boiling salicylic acid with alcohol and a little sulphuric acid, or by dropping an alcoholic solution of salicylic acid into 13-naphthalene sulphonic acid at a temperature of 140-150° C. (German Patent 76,574).
It combines with sulphuric acid to form nitro-sulphonic acid, SO 2 (OH) (N02).
P For sulphonic acids containing nitrogen see Ammonia.
The pure substances are best obtained by fusion of the corresponding toluene sulphonic acids with potash.
It may be prepared by fusion of ortho-toluene sulphonic acid with potash; by the action of phosphorus pentoxide on carvacrol; or by the action of zinc chloride on camphor.
It may be prepared by the fusion of para-toluene sulphonic acid with potash; by the action of nitrous acid on para-toluidine; or by heating para-oxyphenyl acetic acid with lime.
Numerous sulphonic acids of anthracene are known, a monosulphonic acid being obtained with dilute sulphuric acid, whilst concentrated sulphuric acid produces mixtures of the anthracene disulphonic acids.
An important nucleus-synthetic reaction is the saponification of nitriles, which may be obtained by the interaction of potassium cyanide with a halogen substitution derivative or a sulphonic acid.
The a-naphthylamine sulphonic acids are used for the preparation of azo dyes, these dyes possessing the important property of dyeing unmordanted cotton.
Numerous sulphonic acids derived from 0-naphthylamine are known, the more important of which are the 2.8 or Badische, the 2.5 or Dahl, the 2.7 or S, and the 2.6 or Bronner acid.
Various sulphonic acids of anthraquinone are known, as well as oxy-derivatives, for the preparation and properties of which see Alizarin.
Methyl orange (helianthin, gold orange, Mandarin orange), (CH 3) 2 N C 6 H 4 N 2 C 6 H 4 SO 3 Na, is the sodium salt of paradimethylaminobenzene-azo-benzene sulphonic acid.
Numerous di- and tri-sulphonic acids are known.
4), formed when diazotized naphthionic acid (a-naphthylamine-4-sulphonic acid) is boiled with dilute sulphuric acid (Nevile and Winther, Ber., 1880, 1 3, p. 1 949), or when sodium naphthionate is heated with concentrated caustic soda solution under pressure at 240°-260° C. (German patent 46307 (1888)).
The 0-naphthol sulphonic acids find extensive application in the colour industry.
It may be synthetically prepared by the fusion of cymol sulphonic acid with caustic potash; by the action of nitrous acid on 1-methyl-2-amino-4-propyl benzene; by prolonged heating of 5 parts of camphor with r part of iodine; or by heating carvol with glacial phosphoric acid.
Perkin; the method being to sulphonate anthraquinone, and then to convert the sulphonic acid into its sodium salt and fuse this with caustic soda.
It may be prepared synthetically by fusing meta-iodophenol, phenol meta-sulphonic acid, and benzene meta-disulphonic acid with potash; by the action of nitrous acid on meta-aminophenol; or by the action of 10% hydrochloric acid on meta-phenylene diamine (J.
Reinsch on distilling catechin (the juice of Mimosa catechu); occurs free in kino and in beechwood tar; its sulphonic acid is present in the urine of the horse and man.
The mixture can be separated by shaking with sulphuric acid, whereupon the ortho and meta forms are converted into soluble sulphonic acids, the para form being soluble only in concentrated acid; the ortho and meta acids may be separated by crystallization of their salts or sulphonamides.
But its chief technical application depends upon the formation of sulphonic acids when it reacts with aromatic hydrocarbon residues; these compounds being important either as a step towards the preparation of hydroxy-compounds, e.g.
C 2 H 5 SO 2 C1 (chlorides of sulphonic acids), by heating the salts of esters of sulphuric acid with potassium hydrosulphide, and by heating the alcohols with phosphorus pentasulphide.
On oxidation by nitric acid they yield sulphonic acids.
