Benzene → Benzopyran

HRID 2352294Notes

Reaction equation

HRID 2352294 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-efdfb732d8694ca498eaf38e09eb6ccf
Source dataset
uspto-grants-1989_10
Patent number
US04876269

Reaction notes

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