Hydrochloric Acid → 5,7,5',7'-Tetra-tert-butyl-[3,3']bibenzofuranylidene-2,2'-dione

HRID 651882Notes

Reaction equation

HRID 651882 reaction equation
[C:1]([C:5]1[CH:6]=[C:7](C(C)(C)C)[C:8]2[O:12][C:11](=[O:13])[CH:10](O)[C:9]=2[CH:15]=1)([CH3:4])([CH3:3])[CH3:2].S(Cl)(Cl)=O.Cl>C1(C)C=CC=CC=1.CN(C)C=O>[C:1]([C:5]1[CH:15]=[C:9]([C:9]([CH3:15])([CH3:10])[CH3:8])[C:8]2[O:12][C:11](=[O:13])[C:10](=[C:10]3[C:7]4[CH:6]=[C:5]([C:1]([CH3:4])([CH3:2])[CH3:3])[CH:15]=[C:9]([C:1]([CH3:4])([CH3:3])[CH3:2])[C:8]=4[O:12][C:11]3=[O:13])[C:7]=2[CH:6]=1)([CH3:3])([CH3:4])[CH3:2]

Participants

6

Reactant 3

HCID 313Hydrochloric AcidHCID 24386Thionyl ChlorideHCID 68508215,7-Di-tert-butyl-3-hydroxy-2-benzofuranone

Product 1

HCID 534471065,7,5',7'-Tetra-tert-butyl-[3,3']bibenzofuranylidene-2,2'-dione

Reagents, catalysts & solvents 2

HCID 6228DimethylformamideCatalystHCID 1140TolueneSolvent

Procedure

78.7 g of 5,7-di-tert-butyl-3-hydroxy-3H-benzofuran-2-one (prepared as in Ex. 2b) are placed in 150 ml of toluene, and 3 drops of dimethylformamide (DMF) and 45 ml of thionyl chloride are added thereto. The solution is then slowly heated to 373 K at such a rate that the evolution of HCl and SO2 remains vigorous yet controllable. It is then stirred at that temperature for a further hour. Approximately 150 ml of liquid are then distilled off in order to remove the excess thionyl chloride. The residue is diluted with 480 ml of toluene and, at room temperature, 42 ml of triethylamine are added dropwise. The thick, red reaction mixture is then heated under reflux for 15 min. After cooling to room temperature, the triethylamine hydrochloride which has precipitated is filtered off, and the filtrate is washed with water and concentrated NaCl solution and concentrated to an oily consistency using a rotary evaporator. The isoxindigo is crystallised out by adding 225 ml of acetonitrile, is filtered off, washed with acetonitrile and dried, yielding 57.7 g (78.7% of the theoretical yield) of 5,7,5′,7′-tetra-tert-butyl-[3,3′]bibenzofuranylidene-2,2′-dione of formula (LIa).

Workup

  1. distillationApproximately 150 ml of liquid are then distilled off in order
  2. customto remove the excess thionyl chloride
  3. additionThe residue is diluted with 480 ml of toluene and, at room temperature
  4. addition42 ml of triethylamine are added dropwise
  5. temperatureThe thick, red reaction mixture is then heated
  6. temperatureunder reflux for 15 min
  7. customthe triethylamine hydrochloride which has precipitated
  8. filtrationis filtered off
  9. washthe filtrate is washed with water and concentrated NaCl solution
  10. concentrationconcentrated to an oily consistency
  11. customa rotary evaporator
  12. customThe isoxindigo is crystallised out
  13. additionby adding 225 ml of acetonitrile
  14. filtrationis filtered off
  15. washwashed with acetonitrile
  16. customdried
  17. customyielding 57.7 g (78.7% of the

Sources & evidence

ORD record
ord-7a1d72506ecd4b7b9cd46bc98e63b830
Source dataset
uspto-grants-2001_08
Patent number
US06281361B1

Reaction notes

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