Anthraquinone → 2-Chloroanthracene

HRID 1721754Notes

Reaction equation

HRID 1721754 reaction equation
[Cl:1][C:2]1[CH:15]=[CH:14][C:13]2[C:12](=O)[C:11]3[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=3)[C:5](=O)[C:4]=2[CH:3]=1.CCCCCC.C(Cl)Cl.C1C2C(=O)C3C(=CC=CC=3)C(=O)C=2C=CC=1.C1C2C(=CC3C(C=2)=CC=CC=3)C=CC=1>[OH-].[NH4+].O.[Zn].C(Cl)Cl>[Cl:1][C:2]1[CH:15]=[CH:14][C:13]2[C:4](=[CH:5][C:6]3[C:11]([CH:12]=2)=[CH:10][CH:9]=[CH:8][CH:7]=3)[CH:3]=1

Participants

9

Reactant 4

HCID 6780AnthraquinoneHCID 8418AnthraceneHCID 85532-ChloroanthraquinoneHCID 21226440Methylenechloride Hexane

Product 1

HCID 283082-ChloroanthraceneYield 14.4%

Reagents, catalysts & solvents 4

HCID 23994ZincCatalyst2×HCID 962WaterSolventHCID 6344DichloromethaneSolventHCID 14923Ammonium HydroxideSolvent

Conditions

Temperature
40 °C

Procedure

A stirred suspension of 2-chloroanthraquinone (1260 g, 5.19 mol) in concentrated ammonium hydroxide (7.5 L) and water (2.5 L) was warmed to 40° C. Zinc dust (845 g, 12.93 mol) was added in one portion, changing the color to deep red. The mixture was stirred for 45 min at 50° C., then cautiously treated with a second portion of zinc dust (845 g). After the addition, the stirred mixture was heated gradually over 3 h to 90° C., then maintained at 90°-95° C. for 2 h (red color dissipated). TLC analysis (silica gel; hexane:methylene chloride (3:1)) showed complete conversion of the anthraquinone (Rf 0.35) to the desired anthracene (Rf 0.80). The reaction mixture was stirred overnight as it cooled to room temperature. The cooled mixture was treated with methylene chloride (4 L), stirred for 2 h, then filtered through Celite to remove the excess zinc. The filter cake was washed with methylene chloride (6×1 L). The methylene chloride layer was separated from the aqueous, then treated with 6N hydrochloric acid (3 L) and stirred for 2 h. A first crop of 2-chloroanthracene was collected by filtration and washed with water (4×1 L). Vacuum drying afforded a light yellow crystalline product weighing 804.6 g (mp 220°-221° C.). The methylene chloride portion of the filtrate was concentrated in vacuo to 10% of it's original volume. This produced an additional 158.5 g of the desired compound for a total yield of 963.1 g (87.2%). 1H NMR (CDCl3) 8.39 (s, 1H), 8.30 (s, 1H), 7.96 (s, 4H), 7.49 (s, 2H), 7.36 (d, J=8.7 Hz, 1H).

Workup

  1. additionAfter the addition
  2. temperaturethe stirred mixture was heated gradually over 3 h to 90° C.
  3. temperaturemaintained at 90°-95° C. for 2 h (red color dissipated)
  4. stirringThe reaction mixture was stirred overnight as it
  5. temperaturecooled to room temperature
  6. stirringstirred for 2 h
  7. filtrationfiltered through Celite
  8. customto remove the excess zinc
  9. washThe filter cake was washed with methylene chloride (6×1 L)
  10. customThe methylene chloride layer was separated from the aqueous,
  11. additionthen treated with 6N hydrochloric acid (3 L)
  12. stirringstirred for 2 h
  13. filtrationA first crop of 2-chloroanthracene was collected by filtration
  14. washwashed with water (4×1 L)
  15. customVacuum drying
  16. customafforded a light yellow crystalline product
  17. concentrationThe methylene chloride portion of the filtrate was concentrated in vacuo to 10% of it's original volume

Sources & evidence

ORD record
ord-37fc601e5b97486fb0db0b447186a983
Source dataset
uspto-grants-1996_04
Patent number
US05512575

Reaction notes

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