Abstract: 2-Amino-5-alkyl-phenols, which are suitable as intermediates in the production of crop-protection agents or photographic couplers, can be prepared by subjecting 2-amino-5-alkyl-benzenesulphonic acids or their salts to alkaline hydrolysis.

Abstract: Methyl aromatic compounds of the formula (I) ##STR1## in which R.sup.1, R.sup.2 and R.sup.3 have the meaning given in the description,can be reacted in an advantageous manner using free-radicals to give the associated trichloromethyl or tribromomethyl aromatic compounds, if the reaction is carried out in the presence of one or more chlorides or bromides of the heavy alkali metals.

Abstract: Polychloropyrimidines, in particular 4,6-dichloropyrimidine and 2,4,6-trichloropyrimidine, are obtained in a particularly advantageous manner from polyhydroxypyrimidines or tautomeric keto compounds thereof and excess phosphorus oxychloride in the presence of a tertiary amine if, in this reaction,a) 0.75 to 1.5 mol of phosphorus trichloride and 0.7 to 1.

Abstract: The novel compound (2,3-dihydro-5-benzofuranyl)-acetonitrile is prepared by chloromethylating 2,3-dihydro-benzofuran and reacting the resulting 2,3-dihydro-5-chloromethyl-benzofuran with a cyanide. (2,3-Dihydro-5-benzofuranyl)-acetonitrile can be converted by saponification to (2,3-dihydro-5-benzofuranyl)-acetic acid, an important intermediate for the manufacture of various pharmaceutical active substances. This intermediate has hitherto been obtainable only by a laborious procedure and in low yields.

Abstract: Unsubstituted or substituted 2-fluoro-pyrimidines can be prepared by reaction of the underlying 2-amino-pyrimidines with diazotization agents, mixtures of HF and H.sub.2 O containing 30-70% by weight of HF, based on the total of HF and H.sub.2 O, serving as reaction medium. The reaction medium can also contain diluents and/or inorganic salts, preferably fluorides.

Abstract: 2-Chloroacrylonitrile is prepared in a particularly advantageous and readily industrially practicable manner by chlorinating acrylonitrile and then thermally cleaving the 2,3-diehloropropionitrile formed, by chlorinating acrylonitrile in the presence of a catalyst system comprising dimethylformamide and pyridine and/or pyridine derivatives and subjecting the resulting crude 2,3-dichloropropionitrile to thermal cleavage in the presence of the same catalyst system without the addition of further catalysts.

Abstract: 4,6-Dichloropyrimidines are obtained by the reaction of 4,6-dihydroxypyrimidines with excess phosphoryl chloride in a particularly advantageous manner when no base is added, during and/or after the reaction 0.75 to 1.5 mol of phosphorus trichloride and 0.7 to 1.3 mol of chlorine are added per equivalent of exchanged hydroxyl groups so that an excess of phosphorus trichloride with respect to chlorine is always present, and finally phosphorus trichloride and phosphoryl chloride are separated off. This process can be carried out in a particularly simple manner and also continuously.

Abstract: An improved aminomethylation process gives weakly-basic anion exchangers in an elegant way, with by-product obtained being able to be processed into a suitable starting material without problems.

Abstract: 2-Chloropyridine derivatives of the formula (I) ##STR1## in which R represents hydrogen, C.sub.1 -C.sub.4 -alkyl or halogen andn represents 0 to 4,are obtained in good yields and high purity when a 2-aminopyridine derivative of the formula (II) ##STR2## in which R and n have the above definitions,is reacted with nitrosyl chloride in a hydrogen chloride-saturated aqueous solution at temperatures between -10.degree. C. and +50.degree. C. with simultaneous introduction of hydrogen chloride.

Abstract: In the process according to the invention for the preparation of aminoarylsulphonic acids by catalytic hydrogenation of nitroarylsulphonic acids, a substantial increase in the space-time yield in combination with reduced consumption of the catalyst is achieved by dispersing the hydrogen more finely and by limiting according to the invention the concentration of the nitroarylsulphonic acids to be hydrogenated.

Abstract: A process for the preparation of 2-chlorobenzthiazole comprising reacting benzthiazole with elementary chlorine in an inert, boiling solvent in the presence of a catalyst. Advantageously the solvent is phosphorus oxychloride or chlorobenzene, the catalyst is iron-III chloride or aluminum chloride and phosphorus trichloride or pyridine is also present as a co-catalyst. The desired product is obtained in high yield.

Abstract: In the preparation of 3,5-dichloro-.alpha.-methylstyrene by isopropylation of an m/p-dichlorobenzene mixture, isomerization of the resulting alkylation mixture, subsequent side chain bromination of the alkylation mixture and dehydrobromination of the resulting bromination mixture, the improvement which comprises reacting an excess of an m/p-dichlorobenzene mixture which contains at least 50% by weight of m-dichlorobenzene with isopropyl halide, isomerizing the resulting alkylation mixture under pressure in the presence of aluminum chloride until thermodynamic equilibrium has been attained, separating off the isomerized alkylation mixture from the unreacted m/p-dichlorobenzene mixture, and recycling the unreacted mixture for further reaction.

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: A process for producing the magnesium salt of 3-nitro-naphthalene-1,5-disulfonic acid by sulfonating naphthalene, nitrating the sulfonation product, and separating the pure magnesium salt of 3-nitronaphthalene-1,5-disulfonic acid, which process comprises:(a) sulfonating naphthalene with liquid SO.sub.3 in the presence of an inert organic solvent at temperatures between -40.degree. and +20.degree. C.

Abstract: In a process for the preparation of oxalyl chloride from an oxalic acid compound of the formula ##STR1## wherein R.sup.1 and R.sup.2 are identical or different and represent hydrogen or a lower alkyl radical,and phosphorus pentachloride in the presence of phosphorus oxychloride, the improvement wherein the reaction is carried out in the presence of an amino compound of the formula ##STR2## wherein R.sup.3 represents alkyl, aralkyl, aryl or an acyl group, optionally substituted by amino or carboxamido andR.sup.4 and R.sup.5 are identical or different and represent hydrogen or alkyl, aralkyl, or aryl, optionally substituted by amino or carboxamido, orR.sup.4 and R.sup.5 are linked in an optionally substituted carbocyclic ring with 5 to 7 ring members, which optionally contains nitrogen, sulphur and/or oxygen and is optionally substituted by alkyl, aralkyl, aryl and/or amino groups, andR.sup.3 represents hydrogen or alkyl, which can be linked with R.sup.

Abstract: The invention relates to a process for the preparation of 1-amino-8-naphthol-3,6-disulphonic acid (H-acid) as the mono-alkali metal salt from napthylamine-trisulphonic acid isomer mixtures by alkaline hydrolysis under pressure. The separation of the H-acid is effected by utilizing an aqueous sulphuric acid which contains naphthalene- and/or nitronaphthalene- and/or naphthylamine- and/or naphthol- and/or aminonaphthol-mono-, -di-and/or-tri-sulphonic acids.

Abstract: A process for preparing 1,2,4-triazole which comprises contacting hydrazine with formamide in the molar ratio of 1:2.0-2.7 at a temperature from 100.degree. to 250.degree. C. in the presence of ammonia.

Abstract: The invention relates to a method for removing heavy metal sulphides from dilute aqueous systems as they are present in numerous chemical processes. The method is characterized in that water-soluble polymers such as polyethyleneimines, homopolymers or copolymers of derivatives of acrylic acid or methacrylic acid or homopolymers or copolymers of styrenesulphonic acids are added to said systems and the systems are then filtered.

Abstract: A process has been invented for the preparation of naphthalene-1,3,6-trisulphonic acid by sulphonating naphthalene with sulphuric acid and oleum, characterized in that naphthalene and most of the oleum are simultaneously metered into sulphuric acid or oleum of low concentration, which has been initially introduced, at about 140.degree. to 240.degree. C., the temperature is kept at about 140.degree. to 240.degree. C. for some time, the remainder of the oleum is then added at about 140.degree. to 240.degree. C. and the mixture is then further stirred for some time.Naphthalene-1,3,6-trisulphonic acid is a known important intermediate used, for example, in the preparation of T-acid, H-acid and chromotropic acid.

Abstract: A process has been invented for the preparation of aminonaphthalenesulphonic acids by the catalytic hydrogenation of salts of nitronaphthalenesulphonic acids with hydrogen in the presence of Raney nickel catalysts at elevated temperature and pressure, said catalysts comprising a combination of fresh Raney nickel catalyst and Raney nickel catalyst which has already been used in prior hydrogenation or hydrogenations.