摘要:
In the preparation of m-chloroaromatics by isomerizing corresponding o- and/or p-chloroaromatics in the liquid phase over zeolites, the activity of the zeolites remains at a high level for a particularly long time if the process is carried out in the presence of from 1 to 30 mol % of hydrogen, based on the chloroaromatics used.
摘要:
Halogenated benzenes are hydrodehalogenated in a particularly advantageous manner and at low temperatures by contacting them at temperatures of between 100.degree. and 250.degree. C. together with hydrogen with a catalyst prepared by application of one or more salts of palladium and/or platinum and, if desired, of copper to an alumina or titanium dioxide support.
摘要:
In a particularly advantageous process for isolating m-dichlorobenzene from mixtures of dichlorobenzene isomers by crystallization as eutectic crystals using a processing aid, the processing aid used is a compound of the formula (I) ##STR1## in which R.sup.1 to R.sup.6 are, independently of one another, hydrogen, halogen, C.sub.1 -C.sub.4 -alkyl, hydroxyl, NH.sub.2 or R--CO-- having R=C.sub.1 -C.sub.4 -alkyl,with 1-bromo-4-chlorobenzene and 1,4-dibromobenzene being excepted.
摘要:
The present process serves for the hydrodehalogenation of halogenated meta-cresols of the formula (I) in which the R1 to R4 radicals are each as defined in the description, and is characterized in that halogenated meta-cresols of the formula (I) are contacted with a catalyst which has been prepared by applying one or more salts of palladium and/or platinum and optionally copper salts to an aluminum oxide or titanium oxide support material, together with hydrogen, at temperatures between 100 and 250° C.
摘要:
The present process serves for the hydrodehalogenation of halogenated meta-cresols of the formula (I) in which the R1 to R4 radicals are each as defined in the description, and is characterized in that halogenated meta-cresols of the formula (I) are contacted with a catalyst which has been prepared by applying one or more salts of palladium and/or platinum and optionally copper salts to an aluminum oxide or titanium oxide support material, together with hydrogen, at temperatures between 100 and 250° C.
摘要:
Dialkyl dicarbonates are obtained particularly advantageously from halogenoformic esters by reaction with alkalis in the presence of water-immiscible organic solvents and in the presence of a catalyst, if the catalyst used is benzylalkyldimethylammonium halides. The catalyst is then particularly easy to separate off and to recycle from the reaction mixture.