反应详情

温度

2.5 °C

85% Sulfuric acid was made by adding 98% sulfuric acid (13 mL) cautiously to ice (2 g). Guanidine nitrate (1.221 g, 10.00 mmol) was added portionwise over a period of 10 minutes to a cooled (0-5° C.) mixture of 4-bromo-2-methoxyaniline (2.020 g, 10 mmol) in 85% sulfuric acid (15.68 mL, 250.00 mmol). The resulting dark blue mixture was stirred at 0-5° C. for 0.75 h and was then poured very slowly into a well-stirred mixture of 50% aq NaOH (40 mL) and ice (120 g). An orange precipitate was collected by filtration, washed with water (4×50 mL) and air dried. This material was dissolved into diethyl ether (100 mL) and filtered through a silica plug. The resulting solution was diluted with isohexane and purified by evaporative crystallisation from diethyl ether/isohexane to give the title compound (1.821 g, 74%) as an orange crystalline solid; 1H NMR: 3.90 (3H, s), 5.52 (2H, s), 7.14 (1H, s), 7.32 (1H, s).

1. temperaturea cooled
2. filtrationAn orange precipitate was collected by filtration
3. washwashed with water (4×50 mL) and air
4. customdried
5. dissolutionThis material was dissolved into diethyl ether (100 mL)
6. filtrationfiltered through a silica plug
7. additionThe resulting solution was diluted with isohexane
8. custompurified by evaporative crystallisation from diethyl ether/isohexane