METHOD FOR PRODUCING PHTHALIDES

摘要

The invention relates to a method for producing phthalides in which I) phthalate acid or phthalate acid derivatives which are dissolved in an electrolyte are reduced on a cathode in a non-divided electrolysis cell in which the carboxy groups can be replaced by units and can be derived from the carboxy groups in a condensation reaction. One or more hydrogen atoms of the o-phenylene unit can be substituted by inert residues. II) Once the reaction has reached a given stage at which the molar ratio relationship (M) which is formed from the portion of phthalide and the sum of the portion of phthalide, phthalate acid or the phthalate acid derivatives in the electrolyte amounts to 0.8:1 to 0.995:1, the electrolyte from the electrolysis cell is removed and III) the phthalide is crystallized out of the electrolyte and separated from the original solution optionally after distillation reprocessing of said electrolyte.