FIELD: chemical technology. SUBSTANCE: product: water-soluble sulfonates of alkaline metals obtained by composition sulfonation. Composition consists of indene or a mixture of indene with hydrocarbons mixture consisting of at least by 70 wt.-% aromatic hydrocarbons and their alkyl derivatives. At least 75 wt.-% indicated aromatic hydrocarbons contain two or more fused nuclei, total indene content is 20-100 wt.-% in composition, sulfur trioxide at mass ratio 1:(0.8-2.2), respectively, in sulfur dioxide and at 30-120 C followed by neutralization of reaction mass with alkaline metal hydroxide. EFFECT: improved method of preparing. 4 cl, 3 tbl
