Abstract: Methine dyestuffs of the formula ##STR1## are prepared by subjecting a compound ##STR2## to a condensation reaction with a compoundA--CHO (VI)and with 1 to 5 equivalents of an inorganic acid in the presence of 0-30% by weight of an organic solvent and 0-15% by weight of water.

Abstract: Process for the preparation of styryl dyestuffs of the formula ##STR1## in which R.sub.1 and R.sub.2 denote hydrogen, alkyl, alkoxy or halogen andX denotes an alkylene radical,characterized in that compounds of the formula ##STR2## in which X, R.sub.1 and R.sub.2 have the meaning given for formula (I) andR denotes alkyl or aryl,are hydrolyzed by means of mineral acid to give compounds of the formula (I) and the latter are isolated.

Abstract: The preparation of hydrazone dyestuffs of the formula ##STR1## wherein R.sup.13 and R.sup.14 independently of one another represent hydrogen, C.sub.1 -- to C.sub.4 --alkyl, C.sub.1-- to C.sub.4-- alkoxy or halogen, in particular chlorine or bromine, andA.sup.- denotes an anionic radical,by reacting azo bases of the general formula ##STR2## wherein R.sup.13 and R.sup.14 have the above mentioned meaning andR.sup.15 represents hydrogen or the methyl group, with dimethyl sulphate in a mixture of water and an organic solvent and in the presence of an acid-binding agent, is characterized in that (a) aromatic or aliphatic chlorinated hydrocarbons are used as the organic solvents, (b) the reaction is carried out at a temperature of 10.degree.-60.degree. C., (c) a 5-90% excess of dimethyl sulphate is employed and (d) the reaction is allowed to proceed at a pH of 5-10.

Abstract: An improvement in a process for the preparation of dichlorophene by reacting p-chlorophenol with formaldehyde in the presence of sulfuric acid. The improvement lies in contacting p-chlorophenol with the stoichiometric excess of formaldehyde in aqueous sulfuric acid by introducing into a sulfuric acid reaction medium 1 to 6% by weight of the total amount of p-chlorophenol to be reacted and thereafter adding the formaldehyde and additional p-chlorophenol to the reaction mixture in an amount such that at the end of the addition of the p-chlorophenol only 85 to 98% by weight of the total amount of formaldehyde has been added. The balance of the formaldehyde is then introduced into the reaction mixture.

Abstract: Sulfonic acid fluorides are prepared by reacting sulfonic acid halides with inorganic fluorides in an organic-aqueous phase. The reaction is carried out in the presence of catalytic amounts of an amine or an onium salt.