Abstract: A process for the preparation of 2-chloro-5-chloromethyl-1,3-thiazole, in which allyl isothiocyanate of formula CH2═CH—CH2—NCS is reacted at from −40° C. to +30° C., in a solvent that is inert under the reaction conditions, with from 1 to 2 mol of a chlorinating agent per mol of allyl isothiocyanate; to the reaction mixture so obtained there is added, at a reaction temperature of from 0° C. to the boiling temperature of the solvent used, from 1 to 5 mol of oxidising agent per mol of allyl isothiocyanate, and then 2-chloro-5-chloromethyl-1,3-thiazole is isolated from the reaction mixture and is optionally converted by crystallisation into high-purity 2-chloro-5-chloromethyl-1,3-thiazole.

Abstract: A process for the preparation of 2-chloro-5-chloromethyl-1,3-thiazole, in which allyl isothiocyanate of formula CH2═CH—CH2-NCS is reacted at from −40° C. to +30° C., in a solvent that is inert under the reaction conditions, with from 1 to 2 mol of a chlorinating agent per mol of allyl isothiocyanate; to the reaction mixture so obtained there is added, at a reaction temperature of from 0° C. to the boiling temperature of the solvent used, from 1 to 5 mol of oxidising agent per mol of allyl isothiocyanate, and then 2-chloro-5-chloromethyl-1,3-thiazole is isolated from the reaction mixture and is optionally converted by crystallisation into high-purity 2-chloro-5-chloromethyl-1,3-thiazole.

Abstract: A process for the transesterification of dimethyl succinylsuccinate with one or more aliphatic alcohols which in each case have at least 2 C atoms, in the presence of an acidic catalyst and in the presence or absence of a diluent which is inert under the reaction conditions, with exclusion of oxygen and under pressure, at least one of the two methoxy groups being replaced by the oxy group corresponding to the alcohol used and use of the process in a process for the preparation of terephthalic acids and of quinacridones.

Abstract: Process for the preparation of 2-amino-4,6-dichloropyrimidine by reaction of 2-amino-4,6-dihydroxypyrimidine with an excess of phosphorus oxychloride at 20 to 80.degree. C. and in the presence of triethylamine as the acid-trapping agent.

Abstract: A process for the transesterification of dimethyl succinylsuccinate with one or more aliphatic alcohols which in each case have at least 2 C atoms, in the presence of an acidic catalyst and in the presence or absence of a diluent which is inert under the reaction conditions, with exclusion of oxygen and under pressure, at least one of the two methoxy groups being replaced by the oxy group corresponding to the alcohol used.