C([O:3][C:4](=[O:21])[CH2:5][O:6][C:7]1[C:18]([Cl:19])=[C:17]([Cl:20])[C:10]2[S:11][C:12]([C:14](=[O:16])[CH3:15])=[CH:13][C:9]=2[CH:8]=1)C.[OH-].[Na+].Cl.C(OCC)C>C(O)C>[C:14]([C:12]1[S:11][C:10]2[C:17]([Cl:20])=[C:18]([Cl:19])[C:7]([O:6][CH2:5][C:4]([OH:21])=[O:3])=[CH:8][C:9]=2[CH:13]=1)(=[O:16])[CH3:15]
To 5.1 g of ethyl[ (6,7-dichloro-2-acetylbenzo[b]thien-5-yl)oxy]acetate in 200 ml of 95% ethanol is added 150 ml of a 6 N sodium hydroxide solution and the mixture is refluxed at 100° for 45 mins. The solvent is removed in vacuo to give a white slurry to which is added 250 ml of a 6 N hydrochloric acid and 200 ml ethyl ether. The mixture is stirred for 2 hrs, filtered and the filter cake is distributed between 6 N hydrochloric acid and ethyl ether. The organic layers are separated and the aqueous layers are extracted with ethyl ether. The combined organic extracts are washed, dried over anhydrous magnesium sulfate, filtered and the solvent is evaporated to give a solid. Recrystallization from acetone-hexane gives 2.2 g of [(2-acetyl-6,7-dichlorobenzo[b]thien-5-yl)oxy]acetic acid, mp 203°-205°.
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