1.Charge 142.0 g of N-(2,2-dimethoxyethyl)-2-(3,4-dimethoxyphenyl) acetamide, 710 ml of glacial acetic acid and 710 ml of conc. hydrochloric acid in a 3.0 L round bottom flask equipped with mechanical stirrer and thermometer pocket at 25°C.
2.Stir the mixture for 17 hours at 25°C.
3.Monitor the reaction by HPLC (starting material should be less than 4.0%).
4.Pour the reaction mixture on 3.0 kg of crushed ice, if HPLC complies.
5.Stir the mixture for 30 minutes and filter the solid material.
6.Wash the mixture with 1 L of water, suck dry and unload the material.
7.Dry the 7,8-Dimethoxy-1,3-dihydro-2H-3-benzazepin-2-one under vacuum at 55-60°C till the LOD comes to below 0.5%.
