摘要:
When the halogen content of polyhalogenated aromatics is decreased by reaction with monohalogenated and/or non-halogenated aromatics in the gas phase, good yields and significantly improved catalyst service lives are achieved if the reaction is carried out in the presence of a catalyst and in the presence of a hydrogen halide.
摘要:
Dichlorobenzene having an increased p-content and a greatly reduced m-content is obtained by ring chlorination of benzene or chlorobenzene in the presence of Friedel-Crafts catalysts if the reaction is carried out in the presence of co-catalysts of the formula (I) ##STR1## wherein X represents fluorine, chlorine, bromine, trifluoromethyl or pentafluoroethyl andA represents 2 hydrogen atoms or the group --CH.dbd.CH--CH.dbd.CH--.
摘要:
In the preparation of 2-chloro-4-nitro-alkylbenzene by reaction of 4-nitro-alkylbenzene with elemental chlorine or chlorine-releasing compounds in the presence of a Friedel-Crafts catalyst in the liquid phase, particularly high selectivities in respect of the target compounds chlorinated exclusively in the 2-position are achieved if a dibenzo-condensed sulphur heterocycle of the formula ##STR1## having the meanings given in the description for R.sup.1 to R.sup.8, X and n, is used as co-catalyst.
摘要:
Aromatic hydrocarbons which are monosubstituted by straight-chain or branched C.sub.1 -C.sub.12 -alkyl or by C.sub.3 -C.sub.8 -cycloalkyl can be chlorinated in the presence of Friedel-Crafts Catalysts in liquid phase on the aromatic ring if cyclic benzo-fused imines or benzo[f]-1,4-thiazepines are used as co-catalysts. This makes it possible to obtain a higher proportion of p-isomers.
摘要:
N,N-Diaryl-ureas of the formulaR.sup.1 --NR.sup.2 --CO--NH--R.sup.3whereinR.sup.1 and R.sup.2 denote aryl andR.sup.3 denotes alkyl, aralkyl or aryl, can be prepared by a process in which a diarylamine of the formulaR.sup.1 --NH--R.sup.2is reacted with an isocyanate of the formulaR.sup.3 --NCOwherein R.sup.1, R.sup.2 and R.sup.34 have the above meaning, in the presence of acid compounds and in the presence or absence of an inert solvent and/or diluent at elevated temperature.
摘要:
Mixtures of 2- and 4-hydroxybenzyl alcohol with high contents of 4-hydroxybenzyl alcohol are obtained by a process comprising reacting phenol and paraformaldehyde in the presence of a strongly basic catalyst and a polyalkylene polyether.
摘要:
Salicylaldehyde and other hydroxybenzaldehydes are prepared by oxydation of a hydroxybenzyl alcohol in the presence of a platinum metal catalyst and lead, silver, tellurium or tin or compounds thereof as activator.
摘要:
The invention relates to a particularly advantageous method for producing aryl thiols through the catalytic hydrogenation of diaryldisulphides. According to the invention, the hydrogenation is carried out in a basic alcoholic medium.
摘要:
The invention relates to novel S-(4-biphenyl)-thiosulfuric acids and their salts, to a method for producing them from S-(4-biphenyl)-thiosulfinic acids and their salts, and to a method for producing 4-mercaptobiphenyls from the S-(4-biphenyl)-thiosulfuric acids and their salts.
摘要:
2-Chloro-4-methylphenol is prepared by reacting 4-methylphenol with a chlorinating agent in the presence of a catalyst system of one or more Lewis acids in a total amount of 0.1-10% by weight and one or more diaryl sulphides in a total amount of 0.1-10% by weight, all based on the amount of 4-methylphenol. The reaction temperature is 0.degree.-100.degree. C. The chlorinating agent is used in an amount of 0.5-1.5 mol per mole of 4-methylphenol. The reaction can be carried out until virtually complete consumption of the 4-methylphenol, high isomeric selectivity and high stage selectivity being observed.