Abstract: Catalyst for halogen-fluorine exchange reactions on aromatics, consisting essentially of a mixture of one or more compounds of the component a) plus at least one compound of the components b), c) and/or d), whereina) is an amidophosphonium salt of the formula (I) ##STR1## where A.sup.1, A.sup.2, A.sup.3, A.sup.4, A.sup.5, A.sup.6, A.sup.7, A.sup.8 are, independently of one another, identical or different and are each a straight-chain or branched alkyl or alkenyl having from 1 to 12 carbon atoms, cycloalkyl having from 4 to 8 carbon atoms, an aryl having from 6 to 12 carbon atoms, an aralkyl having from 7 to 12 carbon atoms, or A.sup.1 A.sup.2, A.sup.3 A.sup.4, A.sup.5 A.sup.6, A.sup.7 A.sup.8 are, independently of one another, identical or different and are in each case connected to one another either directly or via O or N--A.sup.9 to form a ring having from 3 to 7 ring atoms, A.sup.9 is an alkyl having from 1 to 4 carbon atoms and B.sup..crclbar.

Abstract: The present invention relates to a process for preparing 4,5-dichloro-2-methylbenzoic acid and also its salts in high yields and in high purities by reacting 3,4-dichlorotoluene with acetyl chloride or chloroacetyl chloride in the presence of a Friedel-Crafts catalyst and subsequently oxidizing the acetylated intermediate to give the carboxylic acid.

Abstract: The present invention relates to a process for preparing ortho-nitrobenzonitriles of the formula I, ##STR1## where R.sup.1 and R.sup.2 are as defined in claim 1, by reacting the corresponding ortho-fluoronitrobenzenes with alkali metal cyanides or cyanide-donating substances in the presence of phase transfer catalysts.

Abstract: The present invention relates to a process for preparing 4-bromophenyl alkyl ethers by reacting phenyl alkyl ethers with bromine in a water-miscible solvent in the presence of an oxidizing agent which is able to oxidize hydrogen bromide to bromine.

Abstract: The invention relates to a preparation process for aromatic methyl methoxycarboxylates by reaction of aromatic hydroxycarboxylic acids in the form of a mixture with the methoxycarboxylic acids with dimethyl sulphate in water.

Abstract: The present invention relates to a process for the preparation of methyl 5-bromo-6-methoxy-1-naphthoate by brominating methyl 6-methoxy-1-naphthoate with bromine, in which between 0.5 and 0.6 mol of bromine (Br.sub.2) are employed per mole of methyl 6-methoxy-1-naphthoate and the bromination is carried out in the presence of an oxidant.

Abstract: Azaporphyrin derivatives of the formula ##STR1## where R.sup.1 and R.sup.2 are each, independently of one another, hydrogen, unsubstituted or substituted C.sub.1 -C.sub.20 -alkyl, C.sub.5 -C.sub.7 -cycloalkyl or unsubstituted or substituted phenyl, or two adjacent R.sup.1 radicals form, together with the carbon atoms to which they are bonded, an unsaturated or aromatic 5- to 7-membered carbocyclic ring,X are each hydrogen or C.sub.1 -C.sub.4 -alkyl andp are each 1 or 2, andbiladienes of the formula ##STR2## where R.sup.1, R.sup.2, X and p each have the abovementioned meanings, m and n are each 0 or 1 and An.sup..crclbar. is an anion, as intermediates therefor, are used for preparing vinylogous porphyrin derivatives.