C(O)(=O)C.[CH3:5][O:6][C:7]1[C:15]([O:16][CH3:17])=[CH:14][CH:13]=[C:9]([C:10]([OH:12])=O)[C:8]=1[NH2:18].[O-:19][C:20]#[N:21].[K+].[OH-].[Na+]>O>[CH3:17][O:16][C:15]1[C:7]([O:6][CH3:5])=[C:8]2[C:9]([C:10](=[O:12])[NH:21][C:20](=[O:19])[NH:18]2)=[CH:13][CH:14]=1Acetic acid (177.4 ml., 3.1 moles) was added to a vigorously stirred suspension of 3,4-dimethoxyanthranilic acid (436.5 g., 2.21 moles) in 10 liters of water. Then 2.24 liters of 20% potassium cyanate (5.53 moles) solution was gradually added and the mixture was stirred for one hour at 40° C. After cooling the reaction mixture to 20° C., 3.54 kg. sodium hydroxide pellets were added maintaining the temperature below 40° C. The reaction mixture was heated to 90° C. for 45 minutes and then slowly cooled in an ice bath. The sodium salt of the product was filtered, resuspended in 6 liters of water, acidified with concentrated hydrochloric acid (370 ml.), cooled and filtered to yield 404 grams (82%) of the product. Recrystallization from dimethylformamide gave colorless crystals, M.P. 314°-6° C.
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