Dimethylformamide → 9-ethyl-9H-carbazole-3,6-dicarbaldehyde

HRID 349144

Reaction equation

HRID 349144 reaction equation
P(Cl)(Cl)(Cl)=O.[CH2:6]([N:8]1[C:20]2[CH:19]=[CH:18][CH:17]=[CH:16][C:15]=2[C:14]2[C:9]1=[CH:10][CH:11]=[CH:12][CH:13]=2)[CH3:7].[C:21]([O-:24])(=O)C.[Na+].CN(C)[CH:28]=[O:29]>O>[CH2:6]([N:8]1[C:20]2[CH:19]=[CH:18][C:17]([CH:28]=[O:29])=[CH:16][C:15]=2[C:14]2[C:9]1=[CH:10][CH:11]=[C:12]([CH:21]=[O:24])[CH:13]=2)[CH3:7]

Participants

6

Reactant 4

HCID 6228Dimethylformamide2×HCID 6836N-ethyl carbazoleHCID 24813Phosphorus oxychloride3×HCID 517045Sodium Acetate

Product 1

HCID 37166759-ethyl-9H-carbazole-3,6-dicarbaldehydeYield 46%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

A 271 ml quantity of dimethylformamide (DMF, 3.5 mol) was added to a 1-liter, 3-neck round bottom flask equipped with a mechanical stirrer, a thermometer, and an addition funnel. The contents were cooled in a salt/ice bath. When the temperature inside the flask reached 0° C., 326 ml of phosphorus oxychloride (POCl3, 3.5 mol) was slowly added. During the addition of POCl3, the temperature inside the flask was not allowed to rise above 5° C. After the addition of POCl3, the reaction mixture was allowed to warm to room temperature. After the flask warmed to room temperature, N-ethylcarbazole (93 g) in 70 ml of DMF was added and then the flask was heated to 90° C. for 24 hours using a heating mantle. Next, the reaction mixture was cooled to room temperature and the reaction mixture was added slowly to a cooled 4.5 liter beaker containing a solution comprising 820 g of sodium acetate dissolved in 2 liters of water. The beaker was cooled in an ice bath and stirred for 3 hours. The brownish solid obtained was filtered and washed repeatedly with water, followed by a small amount of ethanol (50 ml). After washing, the resulting product was recrystallized once from toluene using activated charcoal and dried under vacuum in an oven heated at 70° C. for 6 hours to obtain 55 g (46% yield) of N-ethyl-3,6-diformylcarbazole. The 1H-NMR spectrum (250 MHz) of the product in CDCl3 was characterized by the following chemical shifts (δ, ppm): 10.12 (s, 2H); 8.63 (s, 2H); 8.07 (d, 2H); 7.53 (d, 2H); 4.45 (m, 2H); 1.53 (t, 3H).

Workup

  1. customequipped with a mechanical stirrer
  2. temperatureThe contents were cooled in a salt/ice bath
  3. customreached 0° C.
  4. customto rise above 5° C
  5. temperatureAfter the flask warmed to room temperature
  6. temperaturethe flask was heated to 90° C. for 24 hours
  7. temperatureNext, the reaction mixture was cooled to room temperature
  8. additionthe reaction mixture was added slowly to a cooled 4.5 liter beaker
  9. additioncontaining a solution
  10. temperatureThe beaker was cooled in an ice bath
  11. customThe brownish solid obtained
  12. filtrationwas filtered
  13. washwashed repeatedly with water
  14. washAfter washing
  15. customthe resulting product was recrystallized once from toluene using activated charcoal
  16. customdried under vacuum in an oven
  17. temperatureheated at 70° C. for 6 hours

Sources & evidence

ORD record
ord-735a5463e64e4f1697fa71955d60cb30
Source dataset
uspto-grants-2007_02
Patent number
US07179574B2

Linked notes

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