Water → 2-(2-Thienylcarbonyl)benzoic acid

Participants

Reaction Steps

A solution of 74.1 g (0.5 mole) of phthalic anhydride in 300 mL of nitrobenzene was treated with 147 g (1.1 mole) of aluminum chloride. The solution was stirred for two hours and 42.1 g (0.5 mole) of thiophene was added dropwise over 80 minutes at 40°-45°. The reaction was stirred at 50°-55° for two hours and then let sit at room temperature overnight. The reaction was poured into 2.8 L of cold water, stirred, separated, and the nitrobenzene was removed from the nitrobenzene layer by steam distillation. The residue was recrystallized from toluene to provide 31.1 g (27%) of 2-thienoylbenzoic acid, mp 141-143. The thienoylbenzoic acid was treated with methylhydrazine as described in Example 185 to provide 24.4 g (75%) of the phthalazinone product, mp 143-144, after recrystallization from ethyl acetate.

Provenance & Evidence