3-Methylphthalic Acid is a by-product during the synthesis of 3-Methylhexahydrophthalic Anhydride (M312385), a useful reagent for the synthesis ofgeometrical isomers of 1,2,3-trimethylcyclohexane. It can also be used to preparehydroxycarbamoyl carboxylic acids for the flotation of diaspore and aluminosilicate minerals.
Under nitrogen protection, 2,4-dimethoxypyrimidine (1.4 g, 10 mmol) was dissolved in tetrahydrofuran (14 mL), cooled to about 0 C, 1 M magnesium dichloride (2,2,6,6-tetramethylpiperidinium) lithium salt (11 mL, 11 mmol) was added dropwise with stirring, and after completion of the dropwise addition, stirring was continued for 2 hours, and then iodine (2.79 g, 11 mmol), and after maintaining the reaction at low temperature for 2 hours, it was naturally warmed back to room temperature and stirring was continued for 6 hours. The reaction solution was quenched by pouring into aqueous ammonium chloride solution, extracted three times with ethyl acetate, combined, washed, dried and concentrated. After column chromatography of the crude product obtained, 2,4-dimethoxy-5-iodopyrimidine (2.34 g, 88% yield) was obtained.
