Water → Monomethyl terephthalate

Participants

Reaction Steps

To a solution of 448 mg of the thus-obtained o-hydroxyacetophenone in 6 ml of pyridine was added 1.6 g of terephthalic acid monomethylester chloride and the mixture stirred at room temperature for one night. The reaction mixture was poured over water and extracted with ethyl acetate and washed with dilute hydrochloric acid, water, 1N hydrogencarbonate, water, saturated saline solution and dried over MgSO4. The distillation of the solvent and purification by chromatography through silica gel column gave 600 mg (yield: 80.0%) of the derivative of terephthalic acid methyl ester. To a solution of 210 ml of the thus-obtained methylester in 5 ml of pyridine was added 70 mg of caustic potash and the mixture stirred at room temperature for one night. The reaction mixture was poured over 30 ml of 20% acetic acid and then extracted in ethyl acetate. The organic layer was washed with water 2-3 times and dried over MgSO4. The distillation of the solvent and purification by chromatography through silica gel column gave 112 mg (yield: 53.3%) of the rearranged product (IV; R1, R3 =(CH3)2CCH2 (CH3)2, R3 =CH3) as pale yellow needles having a melting point of 161°-162 ° C. when crystallized from CH2Cl2 /hexane. (b)To a solution of 80 mg of the thus obtained rearranged product in 5 ml of acetic acid was added 0.2 ml of sulfuric acid and the mixture refluxed for 30 minutes, whereafter the reaction mixture was poured into water and extracted with ethyl acetate. The resulting organic layer was washed with water until the pH of the washing became 7 and dried over MgSO4. The distillation of the solvent and purification by chromatography through silica gel column gave 32 mg (yield: 41.8%) of the flavone carboxylic acid ester(III; R1, R2 =(CH3)2CCH2CH2C(CH3)2,R3 =CH3,R4 =H;No.4) as colorless flakes having a melting point of 175°-176° C. (recrystallized from methylenechloride/hexane).

Provenance & Evidence