Abstract: Improved process for preparing high-purity, halogen-free o-phthalaldehyde, in which a) tetrahalo-o-xylene is hydrolyzed at a temperature of 155-160° C. and a pressure of from 2 to 5 bar, where appropriate in the presence of a phase-transfer catalyst, to o-phthalaldehyde, which b) is converted in an acidic alcoholic solution at a temperature of from 0 to the reflux temperature into the corresponding dialkoxyphthalane and, subsequently, c) an acetal cleavage is effected by acid hydrolysis at a pH >1.5 to pH 7, resulting in high-purity, halogen-free o-phthalaldehyde.

Abstract: Improved process for preparing high-purity, halogen-free o-phthalaldehyde, in which a) tetrahalo-o-xylene is hydrolyzed at a temperature of 155-160° C. and a pressure of from 2 to 5 bar, where appropriate in the presence of a phase-transfer catalyst, to o-phthalaldehyde, which b) is converted in an acidic alcoholic solution at a temperature of from 0 to the reflux temperature into the corresponding dialkoxyphthalane and, subsequently, c) an acetal cleavage is effected by acid hydrolysis at a pH >1.5 to pH 7, resulting in high-purity, halogen-free o-phthalaldehyde.

Abstract: Improved, safe process for the purification of ketones obtained by ozonolysis and subsequent reduction of the corresponding terpenes, in which, after the ozonolysis and reduction of acyclic mono-, bi- or tricyclic terpenes with ozonizable double bonds, converting the resulting corresponding crude ketone into a high-purity ketone by means of steam distillation at atmospheric pressure or at reduced pressure, extraction of the steam distillate and subsequent distillation.

Abstract: Improved process for the purification and formulation of o-phthalaldehyde in which crude o-phthalaldehyde, obtained by cleavage of an acetal of o-phthalaldehyde by means of acidic hydrolysis, is, optionally by adding an aqueous basic solution, adjusted to a pH of from 1 to 8, and then, after phase separation has taken place, water is distilled off from the phase which contains the aldehyde with very short thermal stress of less than 1 minute at a pressure of between 100 mbar and atmospheric pressure and a temperature of from room temperature to 180° C. on a thin-layer overhead evaporator and o-phthalaldehyde is then stripped off from the distillation bottom which remains with very short thermal stress of less than 1 minute at a pressure of from 0.5 to 50 mbar and a jacket temperature of from 80 to 80° C. via a thin-layer evaporator and the resulting o-phthalaldehyde melt is pelleted at atmospheric pressure and a temperature of from 60 to 80° C.

Abstract: The invention relates to a method for producing hydroxymethylpyridines from the corresponding vinylpyridines by means of ozonisation in an alcohol as solvent and by means of hydrogenation of the peroxide-containing solution produced thereby, in the presence of a hydrogenation catalyst The hydrogenation solution is adjusted to a pH value of 10 to 14 by adding a base and the alcohol is distilled off and the desired hydroxymethylpyridine is isolated in high purity by extracting with an organic solvent and by means of subsequent distillative purification.

Abstract: Improved process for the purification and formulation of o-phthalaldehyde in which crude o-phthalaldehyde, obtained by cleavage of an acetal of o-phthalaldehyde by means of acidic hydrolysis, is, optionally by adding an aqueous basic solution, adjusted to a pH of from 1 to 8, and then, after phase separation has taken place, water is distilled off from the phase which contains the aldehyde with very short thermal stress of less than 1 minute at a pressure of between 100 mbar and atmospheric pressure and a temperature of from room temperature to 180° C. on a thin-layer overhead evaporator and o-phthalaldehyde is then stripped off from the distillation bottom which remains with very short thermal stress of less than 1 minute at a pressure of from 0.5 to 50 mbar and a jacket temperature of from 80 to 80° C. via a thin-layer evaporator and the resulting o-phthalaldehyde melt is pelleted at atmospheric pressure and a temperature of from 60 to 80° C.

Abstract: Improved, safe process for the purification of ketones obtained by ozonolysis and subsequent reduction of the corresponding terpenes, in which, after the ozonolysis and reduction of acyclic mono-, bi- or tricyclic terpenes with ozonizable double bonds, converting the resulting corresponding crude ketone into a high-purity ketone by means of steam distillation at atmospheric pressure or at reduced pressure, extraction of the steam distillate and subsequent distillation.

Abstract: A process for preparing alkyl- or aryloxyacetaldehydes of the formula 1

Abstract: Process for the purification of o-phthalaldehyde in which an alcoholic solution containing the crude, unpurified o-phthalaldehyde is adjusted to a pH between 0 and 3 at a temperature between 0.degree. and 60.degree. C., then an alkaline solution is added, and the corresponding dialkoxyphthalan is extracted from the organic phase and purified by distillation and, when required, converted into the purified o-phthalaldehyde by hydrolysis.