Potassium Carbonate → 2-Methylquinoxaline

Temperature

60 °C

To a solution of 122 g of ortho-toluenediamine (1.0 mole) dissolved in 500 cc of 2 M acetic acid, 250 cc of 4 M sodium acetate solution was added with stirring. The mixture was heated up to 60° C. and poured rapidly into a solution of 298.4 g (1.05 moles) of sodium glyoxal bisulfite in 1500 cc of water previously heated to 60° C. The resulting dark solution was stirred for one hour and it was then cooled down in an ice bath until the temperature had dropped below 10° C. The solution was then neutralized with 120 g of sodium hydroxide pellets. After the sodium hydroxide had dissolved, 500 g of potassium carbonate was added. During the addition of alkali, the solution turned red and a black oil separated out. Most of the oily amine was removed by extraction with pentane or hexane and the combined organic phase was dried over MgSO4, filtered and vacuum dried to give a brown oil that upon distillation gave methyl-quinoxaline (92 g) as a clear pale yellow to colorless liquid (80% yield).

1. temperaturepreviously heated to 60° C
2. stirringThe resulting dark solution was stirred for one hour
3. temperatureit was then cooled down in an ice bath until the temperature
4. additionhad dropped below 10° C
5. additionDuring the addition of alkali
6. customa black oil separated out
7. customMost of the oily amine was removed by extraction with pentane or hexane
8. dry with materialthe combined organic phase was dried over MgSO4
9. filtrationfiltered
10. customvacuum dried
11. customto give a brown oil that
12. distillationupon distillation

ORD record

ord-c926f4c1a1d245e7adeba4806c0597cf

Source dataset

uspto-grants-2004_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06750343B2