Phosphorus oxychloride → 2-Chloro-9-formylanthracene

N-methylformanilide (2.45 kg, 18.12 mol) was treated with phosphorus oxychloride (2.66 kg, 17.35 mol) over a 40 min period at ambient temperature. The intermediate Vilsmeier complex was stirred for 2 h at room temperature, then treated with 2-chloroanthracene (described in Example 1a) (963 g, 4.53 mol), and o-dichlorobenzene (1.0 L). The resulting bright yellow mixture was heated gradually over 1.5 h to 9° C. at which point an exotherm ensued raising the reaction temperature to 115° C. The heat was removed until the exotherm subsided (45 min)., after which time the mixture was heated for 9 h at 90° C., then cooled. TLC analysis (silica gel; ethyl acetate:hexane 1:4) showed a small amount of unreacted anthracene (Rf 0.90), a small amount of the 3-chloro isomer (Rf 0.65), and the 2-chloro isomer (Rf 0.58) as the major component. The cooled reaction mixture was poured into ice/water (27 L) precipitating a dark brown tar. The aqueous layer was decanted away from the tar and extracted with methylene chloride (5×2 L). The combined extracts were used to redissolve the tar. The methylene chloride solution was washed with 3 N hydrochloric acid (4×1.5 L), followed by water (2 L), then dried over magnesium sulfate. The extracts were filtered, then pressure-filtered through a bed of silica gel, eluting with methylene chloride until all of the desired compound had been recovered. The eluent was concentrated on the rotary evaporator to give a slurry of bright yellow crystals (in o-dichlorobenzene). The crystals were collected by filtration, washed with diethyl ether (2×500 ml), then vacuum dried to afford 619.7 g (56.9%) of the desired 2-chloro-9-formylanthracene (mp 148°150° C.). NMR (CDCl3) 11.35 (s, 1H), 9.02 (d, J=0.9 Hz, 1H), 8.81 (d, J=8.9 Hz, 1H), 8.56 (s, 1H), 7.98 (m, 1H), 7.90 (d, J=8.9 Hz, 1H), 7.66 (m, 1H), 7.53 (m, 1H), 7.42 (m, 1H)

1. temperatureThe resulting bright yellow mixture was heated gradually over 1.5 h to 9° C. at which point an exotherm
2. temperatureensued raising the reaction temperature to 115° C
3. customThe heat was removed until the exotherm
4. custom(45 min)
5. temperature, after which time the mixture was heated for 9 h at 90° C.
6. temperaturecooled
7. customThe cooled reaction mixture
8. customprecipitating a dark brown tar
9. customThe aqueous layer was decanted away from the tar
10. extractionextracted with methylene chloride (5×2 L)
11. dissolutionto redissolve the tar
12. washThe methylene chloride solution was washed with 3 N hydrochloric acid (4×1.5 L)
13. dry with materialdried over magnesium sulfate
14. filtrationThe extracts were filtered
15. filtrationpressure-filtered through a bed of silica gel
16. washeluting with methylene chloride until all of the desired compound
17. customhad been recovered
18. concentrationThe eluent was concentrated on the rotary evaporator
19. customto give a slurry of bright yellow crystals (in o-dichlorobenzene)
20. filtrationThe crystals were collected by filtration
21. washwashed with diethyl ether (2×500 ml)
22. customvacuum dried

ORD record

ord-8d94be50c1f742f18dcafcd8a5b1390e

Source dataset

uspto-grants-1995_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05455246