反应详情

In a closed system equipped with a Dean-Stark trap, a stirred solution of 4,4-dichlorobenzoin (10.0 g, 0.0357 mole), ethanolamine (2.35 g, 0.0385 mole), and a catalytic amount of p-toluenesulfonic aid in 250 ml toluene was heated at reflux temperature for 4 hours and the azeotroped water was collected in the Dean-Stark trap. After cooling, the toluene solution was washed with water, dried over magnesium sulfate and concentrated to an oil. The oil was dissolved in ether, treated with excess ethereal hydrogen chloride and the salt collected under nitrogen. Upon trying to recrystallize the salt from 350 ml of isopropyl ether (necessary for complete solution), 500 ml isopropyl ether, a yellow solid was obtained from this solution which was identified as 4,4'-dichlorobenzil. The filtrate was concentrated to 50 ml and isopropyl ether added to the hot solution until a faint turbidity was obtained. On standing overnight, a white solid was obtained, m.p. 177°-182° C. Recrystallization of the white solid from methanol-isopropyl ether and from acetonitrile-methanol yielded only semisolid salts. These were triturated with methyl ethyl ketone and dried to give 2.04 g total, m.p. 188°-193° C. This material gave a satisfactory elemental analysis for the title compound.

1. customIn a closed system equipped with a Dean-Stark trap
2. temperatureat reflux temperature for 4 hours
3. customthe azeotroped water was collected in the Dean-Stark trap
4. temperatureAfter cooling
5. washthe toluene solution was washed with water
6. dry with materialdried over magnesium sulfate
7. concentrationconcentrated to an oil
8. dissolutionThe oil was dissolved in ether
9. additiontreated with excess ethereal hydrogen chloride
10. customthe salt collected under nitrogen
11. customto recrystallize the salt from 350 ml of isopropyl ether (necessary for complete solution), 500 ml isopropyl ether
12. customa yellow solid was obtained from this solution which
13. concentrationThe filtrate was concentrated to 50 ml and isopropyl ether
14. additionadded to the hot solution until a faint turbidity
15. customwas obtained
16. customa white solid was obtained
17. customRecrystallization of the white solid from methanol-isopropyl ether
18. customfrom acetonitrile-methanol yielded only semisolid salts
19. customThese were triturated with methyl ethyl ketone
20. customdried
21. customto give 2.04 g total