Water → Benzoic Acid

A mixture of 1,2,3-Trimethoxybenzene (1.48 g) and 2-hydroxy-3,4,5-trimethoxybenzoic acid (2.00 g) is stirred in 40 ml of ≈9% solution of P2O5 in methanesulfonic acid at room temperature in a stoppered flask for 4 hours. The 2-hydroxy-3,4,5-trimethoxybenzoic acid was obtained by the method of Mayer and Fikentscher (Mayer and Fikentscher (1956) Chem. Ber. 89:511) from 3,4,5-trimethoxybenzoic acid by bromination and then copper-catalyzed replacement of bromine (by OH) of 2-bromo-3,4,5-trimethoxybenzoic acid. The resultant orange mixture is poured onto crushed ice (500 ml) producing an unfilterable gummy precipitate. This crude product is then subjected to base-catalyzed ring closure by heating in a beaker in 100 ml of 40% ethanol and 10 ml of 10N NaOH just below boiling point. As the mixture reaches 80° C., a white flocculent product appears. The temperature is maintained just below the boiling point and the volume is kept constant by addition of water. After 5 hours, the supernatant is bright yellow and a mass of the precipitate has formed. Heating is continued for 4 more hours. Cooling, filtering (by suction) and washing with water afforded 1.37 g of analytically pure 2,3,4,5,6-pentainethoxyxanthone (yield approximately 45% relative to benzoic acid). This base-catalyzed ring closure is illustrated below:

1. additionThe resultant orange mixture is poured
2. customproducing an unfilterable gummy precipitate
3. customreaches 80° C.
4. temperatureThe temperature is maintained just below the boiling point
5. customa mass of the precipitate has formed
6. temperatureHeating
7. temperatureCooling
8. filtrationfiltering (by suction)
9. washwashing with water

ORDレコード

ord-d6aaf612a41b4a35ab767e3b4dc9da96

出典データセット

uspto-grants-2003_09

DOI

10.6084/m9.figshare.5104873.v1

特許番号

US06613797B2