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

HRID 651881Notes

Reaction equation

HRID 651881 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>ClC1C=CC=CC=1Cl.CN(C)C1C=CN=CC=1>[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 142844-(Dimethylamino)pyridineCatalystHCID 72391,2-DichlorobenzeneSolvent

Procedure

10 g of 5,7-di-tert-butyl-3-hydroxy-3H-benzofuran-2-one (prepared as described in Ex. 1a of U.S. Pat. No. 5,614,572) are placed in 25 ml of 1,2-dichlorobenzene, and 0.5 g of 4-dimethylaminopyridine and 3 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 ½ hour. The temperature is then increased to reflux temperature. After 75 min, the 1,2-dichlorobenzene is distilled off, under reduced pressure at the end. The isoxindigo is crystallised out by adding 30 ml of acetonitrile to the residue, is filtered off, washed with acetonitrile and dried, yielding 6.8 g (73% of the theoretical yield) of 5,7,5′,7′-tetra-tert-butyl-[3,3]bibenzofuranylidene-2,2′-dione of formula (LIa).

Workup

  1. temperatureThe temperature is then increased
  2. temperatureto reflux temperature
  3. waitAfter 75 min
  4. distillationthe 1,2-dichlorobenzene is distilled off, under reduced pressure at the end
  5. customThe isoxindigo is crystallised out
  6. additionby adding 30 ml of acetonitrile to the residue
  7. filtrationis filtered off
  8. washwashed with acetonitrile
  9. customdried
  10. customyielding 6.8 g (73% of the

Sources & evidence

ORD record
ord-947bc6b7ea874cdd98e81adbdf4d4098
Source dataset
uspto-grants-2001_08
Patent number
US06281361B1

Reaction notes

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