反应详情

A solution of o-phenylenediamine (5.4 g, 0.05 mole) and 2,2-dimethylsuccinic acid (7.5 g, 0.05 mole) in 50 mL of 4.8 N HCl was refluxed without condenser until the total volume was reduced to about 20 mL. Evaporation at 100° and 40 torr afforded a green paste which was taken up in 100 mL H2O and made alkaline (pH 9) with 20% NaOH. The mixture was filtered removing tarry matter and the clear yellow filtrate was concentrated, cooled and the pH adjusted to about 6 by addition of acetic acid. A light yellow solid precipitated and was isolated by filtration and dried in air to give 9 g of α,α-dimethyl-1H-2-benzimidazolepropanoic acid, m.p. 223°-226° (dec). Recrystallization from acetonitrile-methyl ethyl ketone-methanol (30-30-40) afforded 6.7 g (61%) of colorless needles, m.p. 266°-267° (dec).

1. customEvaporation at 100°
2. custom40 torr afforded a green paste which
3. filtrationThe mixture was filtered
4. customremoving tarry matter
5. concentrationthe clear yellow filtrate was concentrated
6. temperaturecooled
7. additionthe pH adjusted to about 6 by addition of acetic acid
8. customA light yellow solid precipitated
9. customwas isolated by filtration
10. customdried in air