heating in aqueous N-NaOH (12-0 ml.). The solution, cooled to room temp., was mixed with a cold solution of KMnO4 (2-107 g._3 atoms of 0) in water (100 ml.). The mixture was kept at room temp. overnight and acidified with 2N-H2SO4, and SO2 was passed to give a clear colourless solution, which was evaporated to about 50 ml. The resulting colourless crystalline solid (1.38 g.; m.p. 180-181' with effervescence) was collected, and ether extraction of the filtrate gave 0-94 g. of less pure material, m.p. 140-1500. The first crop was purified by crystallization from water, giving 3:4-dimethoxy-5-methylphthalic acid as colourless prisms, m.p. 184-185°(with effervescence) (Found: C, 54-6; H, 4-99; OMe, 26-2%; titration equiv., 123-6. C0LH1206 requires C, 55-0; H, 5-03; 2 OMe, 25-8 %; equiv. titrating as a dibasic acid, 120-1). The above acid (114 mg.) was heated at 185-190' for 10 min., cooled and sublimed in high vacuum at 85-90°. The sublimate (96 mg., m.p. 114°) was crystallized from dry isopropyl ether, giving 3:4-dimethoxy-5-methylphthalic anhydride (61 mg.) as colourless needles, m.p. 118°

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