Patent ID: 6486358
Filing Date: 2002-11-26
Classification: C07C

Abstract:
An improved process for the purification and formulation of o-phthalaldehyde, wherein crude o-phthalaldehyde, obtained by cleavage of an acetal of o-phthalaldehyde by means of acidic hydrolysis,a) 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, b) water is distilled off from the phase which contains the aldehyde with very short thermal stress of less than 1 minute at a pressure between 100 mbar and atmospheric pressure and a temperature of from room temperature to 180Â° C. on a thin-layer evaporator and c) o-phthalaldehyde is then stripped off overhead 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 180Â° C. via a thin-layer evaporator and d) the resulting o-phthalaldehyde melt is pelleted at atmospheric pressure and a temperature of from 60 to 80Â° C., giving pale yellow o-phthalaldehyde in high purity and storage-stable form.