Some alkylnaphthalene sulphonic acids

Abstract

Compounds of the types(a) Tri-isopropylnaphthalenesulphonic acids(b) Isopropylnaphthalene disulphonic acids(c) Methylisopropylnaphthalenesulphonic acid(d) tert Butylnaphthalenesulphonic acid and(e) Isopropyltetralin sulphonic acid have been studied. (a) Tri-isopropylnaphthalenesulphonic acids. have been prepared from the corresponding sodium and potassium salts of naphthalenesulphonic acids ( made by the action of 100% sulphuric acid at 40 - on naphthalene, and subsequent neutralisation) by the action of isopropyl alcohol and excess 100% sulphuric acid for 16 hours at 40 - 45. The acids so formed have been desulphonated, and the same parent hydrocarbon obtained. Many derivatives of the two have also been studied. (b) The preparation of Isopropylnaphthalene disulphonic acids was attempted using sodium naphthalene 1.5 and 2.7 disulphonates, but under the necessary experimental conditions, desulphonation occurred, and no disulphonic acid could be isolated. (c)Methylisopropylnaphthalenesulphonic acid has been prepared as the potassium salt by the isopropylation of the potassium salt of 1 .Methylnaphthalene-4-sulphonic acid, formed from treating 1-Methylnaphthalene with chlorosulphonic acid at 0.The chloride and aniline salt were also studied. (d) Tert-Butylnaphthalene was prepared by shaking, naphthalene in P.E. solution with isobutyl alcohol for 24 hours. The purified hydrocarbon was then used in the preparation of the corresponding acid, being sulphonated with 100% sulphuric acid at 50 . Attempts to prepare this acid using methods analogous to those previously described, were unsuccessful. Investigations were also carried out on various salts and derivatives of the acid.(e) isopropyltetralinsulphonic acid. The most successful method of preparation was found to be as follows;- Tetralin was condensed with concentrated sulphuric acid and the appropriate amount of 30% fuming acid added to bring the strength to 100%.This mixture was added to isopropyl alcohol in sulphuric acid, and after 20 hours stirring at 45, the required acid (1) was isolated as the barium salt. The parent hydrocarbon, and various salts and derivatives have been investigated. It has been found that certain compounds of the alkylnaphthalene sulphonic acid type have the property, when dissolved in water, of lowering its surface tension, thus rendering wetting of fabrics immersed in it much more rapid, even when they are present in minute proportions. in the patent literature, this property has been ascribed to the presence of several isopropyl groups, and to several sulphonic acid groups. The main object of the present research was to obtain such compounds, whose wetting properties could be tested. Those examined fall into five main groups. Firstly, bearing in mind the fact that the presence of several isopropyl groups was thought to be necessary tri.isopropyl-naphthalene and its two sulphonic acids were prepared. When the preparation of alkyl disulphonic acids was attempted. The other types of compounds tried were methyl isopropyl, and tert.butylderivatives, and the isopropyl derivatives of tetralin.