反应详情

温度

-3 °C

To a 2 L round bottom flask containing a magnetic stirred suspension of commercial 5-bromo-2-chlorobenzoic acid (410 g, 1.74 mol) in 700 mL of CH2Cl2 was added oxalyl chloride (235 g, 1.85 mol) followed by 1.5 mL of DMF. To trap the resultant HCl, the flask was fitted with tubing so that the gas was discharged above the surface of a stirred aq KOH solution. When the vigorous evolution of gas ceased after two hours, the homogeneous reaction was stirred overnight prior to removal of the volatiles under vacuum using a rotary evaporator. The resultant oil solidified during subsequent evacuation. After dissolving the crude 5-bromo-2-chlorobenzoyl chloride in 530 mL of the ethylbenzene, the yellow solution was cooled to −3° C., prior to adding AlCl3 (257 g, 1.93 mol) in ˜30 g portions over 60 min to insure that the temperature did not exceed 10° C. The copious amounts of HCl gas which began to evolve after 60% of the AlCl3 had been added were trapped by passing the gas over a stirred conc. NaOH solution. If the reaction were more concentrated, a magnetic stirred could not have maintained stirring upon completion of the addition of AlCl3. After stirring for 1 h as the bath warmed to ˜15° C., the bath was removed. After 4 h at 20° C., the thick syrup was poured over ice (1.5 kg). Subsequently, once the stirred suspension had cooled, H2O (1 L) was added prior to being extracted four times with 1N HCl, three times with 1M KOH, and twice with brine prior to drying over Na2SO4. The volatiles were removed using first a rotary evaporator and then by heating at 60° C. at 1 Torr. 1H-NMR analysis of the resultant dark oil revealed the residue to be a 1:14 mixture of ortho/para isomers. Dissolution in hexane and followed by filtration through a silica gel pad removed most of the color. Concentration of the eluent yielded 560 g (99% of the 14:1 mixture of the (5-bromo-2-chlorophenyl)(4-ethylphenyl)methanone/(5-bromo-2-chlorophenyl)(2-ethylphenyl)methanone).

1. additionTo a 2 L round bottom flask containing
2. customthe homogeneous reaction
3. customto removal of the volatiles under vacuum
4. customa rotary evaporator
5. dissolutionAfter dissolving the crude 5-bromo-2-chlorobenzoyl chloride in 530 mL of the ethylbenzene
6. customdid not exceed 10° C
7. additionhad been added
8. concentrationIf the reaction were more concentrated
9. stirringa magnetic stirred could not
10. temperaturehave maintained
11. stirringstirring upon completion of the addition of AlCl3
12. stirringAfter stirring for 1 h as the bath
13. temperaturewarmed to ˜15° C.
14. customthe bath was removed
15. waitAfter 4 h at 20° C.
16. additionthe thick syrup was poured over ice (1.5 kg)
17. temperatureSubsequently, once the stirred suspension had cooled
18. additionH2O (1 L) was added
19. extractionto being extracted four times with 1N HCl, three times with 1M KOH
20. dry with materialtwice with brine prior to drying over Na2SO4
21. customThe volatiles were removed
22. customa rotary evaporator
23. temperatureby heating at 60° C. at 1 Torr
24. additiona 1:14 mixture of ortho/para isomers
25. dissolutionDissolution in hexane
26. filtrationfollowed by filtration through a silica gel pad
27. customremoved most of the color
28. customConcentration of the eluent yielded 560 g (