Benzene → Benzopyran

HRID 1085484Notes

Reaction equation

HRID 1085484 reaction equation
[O:1]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[CH:4](O)[CH2:3][CH2:2]1.C1C=CC=CC=1.C1(C)C=CC(S(O)(=O)=O)=CC=1>O>[O:1]1[C:10]2[CH:9]=[CH:8][CH:7]=[CH:6][C:5]=2[CH:4]=[CH:3][CH2:2]1

Participants

5

Reactant 3

HCID 241BenzeneHCID 6101p-Toluenesulfonic acidHCID 92890Chroman-4-ol

Product 1

HCID 9211BenzopyranYield 764.2%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

A mixture of 4-chromanol (30 g; 0.02 mole), benzene (200 ml) and 4-toluenesulfonic acid (200 mg) was refluxed, with a Dean-Stark trap, until separation of water ceased (ca. 3 hrs.). It was then washed successively with saturated NaHCO3 aqueous solution and water, dried over anhydrous MgSO4 and evaporated under reduced pressure to yield an almost colorless liquid which was distilled under vacuum to give benzopyran (20.2 g, 76.4%) b.p. 73°-78°/3 torr.

Workup

  1. custom(ca. 3 hrs.)
  2. washIt was then washed successively with saturated NaHCO3 aqueous solution and water
  3. dry with materialdried over anhydrous MgSO4
  4. customevaporated under reduced pressure
  5. customto yield an almost colorless liquid which
  6. distillationwas distilled under vacuum

Sources & evidence

ORD record
ord-dac984963e6d49e99ec6d9fb294b14b9
Source dataset
uspto-grants-1991_04
Patent number
US05010085

Reaction notes

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