Benzene → Benzopyran

HRID 2249214Notes

Reaction equation

HRID 2249214 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-4e822c5e8de64596ae6706c286c3b76f
Source dataset
uspto-grants-1991_08
Patent number
US05043350

Reaction notes

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