Abstract: Aminoaryl-sulphonic acids can be prepared by reaction of arylamines and sulphuric acid at elevated temperature and under pressure, where water formed and, where appropriate, water present as water of dilution, is left in the reaction mixture until the end of the reaction.

Abstract: A new process for the preparation of aromatic sulphonic acids, in which the sulphonation of the aromatic compounds is carried out with sulphur trioxide in organic solvents in the presence of hydrogen halide.

Abstract: Aromatic aminosulphonic acids which have a reduced content of discoloring by-products are obtained when aromatic amines are reacted with a sulphonating agent in a reaction medium at least some of which consists of tetramethylene sulphone.

Abstract: Aminoarylsulphonic acids which have a relatively high purity and a relatively low content of aminoaryldisulphonic acids can be obtained, if they are prepared, from the corresponding arylammonium hydrogen sulphates, by an improved version of the so-called baking process, wherein the reaction is carried out under pressure at a temperature of at least 140.degree. C. and, at least partially, in the presence of water.

Abstract: In a process for the preparation of 4-nitrotoluene-2-sulphonic acid by reacting 4-nitrotoluene with gaseous sulphur trioxide at an elevated temperature, the improvement wherein molten 4-nitrotoluene is reacted with gaseous sulphur trioxide at a temperature in the range from 60.degree. to 150.degree. C. under a pressure above the vapor pressure of 4-nitrotoluene, in a molar ratio of sulphur trioxide to 4-nitrotoluene of 0.1:1 to 1.5:1, and, after a conversion of at least 70 percent of the reaction component not employed in excess is achieved, the sulphonation mixture is treated with water.

Abstract: A process for delignifying lignocellulosic material with a digestion liquor of nitroanthraquinones and/or dinitroanthraquinones. The process can be carried out in a closed reaction vessel at temperatures of 150.degree.-200.degree..+-. C. for 0.5 to 480 minutes with 0.001 to 10% nitroanthraquinone and/or dinitroanthraquinone by weight of lignocellulosic material.

Abstract: Alkali metal salts of hydroxybenzoates are claimed which are substantially anhydrous and free from hydrobenzoic acid and have the formula ##STR1## in which R.sup.1 denotes alkyl, alkenyl, cycloalkyl or aralkyl,R.sup.2 and R.sup.3 are identical or different and represent hydrogen, halogen, hydroxyl, amino, alkylamino, alkyl, alkoxy, aralkyl or aryl andMe denotes an alkali metal.Furthermore a process for the preparation of the said alkali metal salts of hydroxybenzoates, which are substantially anhydrous and free from hydrobenzoic acid, characterized in that a solution or suspension of a hydroxybenzoate of the formula ##STR2## in which R.sup.1, R.sup.2 and R.sup.3 have the abovementioned meaning, is neutralized with an alkali metal hydroxide at -10.degree. to +50.degree. C. until the degree of neutralization is 0.95 to 1.05, a degree of neutralization of 1.