Abstract: The invention relates to a method for producing 2-oxindoles from the corresponding isatines of formula (I), wherein R can be H, CH3, phenyl or benzyl and R1 can be H, C1-C4-alkyl, C1-C4-alkoxy, phenyl phenoxy, halogen, amino, nitro or hydroxy. Said isatines are converted by means of hydrazine hydrate in a polar solvent at a temperature of 15 to 185° C. to form a corresponding isatine hydrazone which directly undergoes further reaction to form the corresponding 2-oxindole of formula (II) by adding diazabicyclooctane and/or diazabicycloundecane and/or ethyldiisopropylamine as a catalyst in temperatures of 100 to 185° C., whereby the produced reaction water is distilled off. According to formula (II), R and R1 have the aforementioned definitions. The 2-oxindole is isolated from the reaction mixture by distilling off the solvent and by means of crystallisation.

Abstract: The invention relates to a method for producing 2-oxindoles from the corresponding isatines of formula (I), wherein R can be H, CH3, phenyl or benzyl and R1 can be H, C1-C4-alkyl, C1-C4-alkoxy, phenyl, phenoxy, halogen, amino, nitro or hydroxy. Said isatines are converted by means of hydrazine hydrate in a polar solvent at a temperature of 15 to 185° C. to form a corresponding isatine hydrazone which directly undergoes further reaction to form the corresponding 2-oxindole of formula (II) by adding diazabi-cyclooctane and/or diazabicycloundecane and/or ethyldiisopropylamine as a catalyst in temperatures of 100 to 185° C., whereby the produced reaction water is distilled off. According to formula (II), R and R1 have the aforementioned definitions. The 2-oxindole is isolated from the reaction mixture by distilling off the solvent and by means of crystallisation.

Abstract: A process for the purification of recovered or regenerated phosphorus oxychloride contaminated by reactive organic compounds, by reacting the contaminated phosphorus oxychloride with from 0.1 to 5% by weight of an organic amine, having 1 or 2 tertiary N-atoms and a boiling point above the boiling point of phosphorus oxychloride, at the boiling temperature of the reaction mixture and subsequently carrying out fractional distillation at atmospheric pressure to obtain purified phosphorus oxychloride.