| 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 DEG 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) in converted in an acidic alcoholic solution at a temperature of from 0 to the reflux temoerature into the corresponding dialkoxyphthalane and, subsequently, (c) an acetal cleavage is effected by acid hydrolysis at a pH >1.5 to pH7, resulting in high-purity, halogen-free o-phthalaldehyde. |