Abstract: The invention concerns new sulfonation products of naphthalene, process for their preparation according to which naphthalene is sulfonated under special reaction conditions by sulfur trioxide in inert organic solvents. The new sulfonation products are used as intermediates e.g. for the production of naphthalene-1,5-disulfonic acid.

Abstract: Improved process for the preparation of nitronaphthalene-sulphonic acids by reacting the corresponding naphthalene-sulphonic acids with nitric acid and working up the nitration mixture, characterized by the features that the reaction of the naphthalene-sulphonic acids with nitric acid is already interrupted before the nitration reaction has ended and that the nitration mixture is treated, optionally after dilution with water, with bases at a pH value of 5 to 14.

Abstract: The invention relates to a method for the drying and removal of hydrocarbons from gases.It is the object of the invention to increase the absorption ability of the solvent for aromatic hydrocarbons including naphthalene and water, to save material and energy, to lower the investment- and operating costs, as well as to avoid operational disturbances and to increase the safety during gas treatment, gas transmittance and gas distribution. This object is accomplished by the invention in that a mixture of glycol, N-methyl-.epsilon.-caprolactam and water is used as solvent. The mixture comprises 79.9 to 97 percent by weight of glycol, 2 to 20 percent by weight of N-methyl-.epsilon.-caprolactam and 0.1 to 1 percent by weight of water. The regeneration temperature of the charged solvent mixture is 150.degree. to 190.degree. C., preferably 170.degree. C. 3 to 15 percent by weight, preferably 10 percent by weight, of crude benzene is added to the charged solvent mixture.

Abstract: The process for preparing 1-amino-2-naphthol-4-sulphonic acid by acidifying 3-oxo-4-hydroxyimino-1,2,3,4-tetrahydronaphthalene-1-sulphonic acid or its alkali metal salt in the presence of hydrogen sulphite is carried out in the presence of iron ions.

Abstract: The invention relates to a process for isolating H acid and K acid in the form of their monoalkali metal salts from acid aqueous solutions which contain these two acids and alkali metal ions and may contain other aminonaphtholdisulphonic acids, in which process H acid monoalkali metal salts are precipitated at elevated temperatures from solutions which contain not only sodium ions but also potassium ions and then precipitating K acid monoalkali metal salts by cooling down the filtrate obtained after separating off the H acid monoalkali metal salts.