Pyrogallol → 3,4-Dihydro-2H-benzo[b][1,4]dioxepin-6-ol

HRID 224800Notes

Reaction equation

HRID 224800 reaction equation
[C:1]1([CH:9]=[CH:8][CH:7]=[C:5]([OH:6])[C:3]=1[OH:4])[OH:2].[OH-].[K+].Br[CH2:13][CH2:14][CH2:15]Br>>[O:2]1[C:1]2[CH:9]=[CH:8][CH:7]=[C:5]([OH:6])[C:3]=2[O:4][CH2:15][CH2:14][CH2:13]1

Participants

4

Reactant 3

HCID 1057PyrogallolHCID 80011,3-DibromopropaneHCID 14797Potassium Hydroxide

Product 1

HCID 141805693,4-Dihydro-2H-benzo[b][1,4]dioxepin-6-ol

Procedure

63 G. of pyrogallol are dissolved with stirring in 330 ml. of absolute alcohol in a flask under a nitrogen atmosphere. 56 G. of potassium hydroxide are added to the flask and the temperature of the reaction mixture rises to 65° C. To the resulting dark-brown, clear solution, 200 g. of 1,3-dibromopropane are added dropwise a over 30 minute period. The resulting mixture is refluxed overnight with stirring. The mixture is cooled to room temperature and filtered. The ethanolic solution is evaporated to dryness and the residual oil is dissolved in 200 ml. of ether. The ether solution is washed several times with water, dried over sodium sulfate, filtered and evaporated to dryness. A dark oil, 3,4-dihydro-2H-1,5-benzodioxepin-6-ol is obtained. This oil is recrystallized from ether and petroleum ether to yield white crystals, m.p. 112°-114° C.

Workup

  1. customrises to 65° C
  2. temperatureThe resulting mixture is refluxed overnight
  3. stirringwith stirring
  4. filtrationfiltered
  5. customThe ethanolic solution is evaporated to dryness
  6. dissolutionthe residual oil is dissolved in 200 ml
  7. washThe ether solution is washed several times with water
  8. dry with materialdried over sodium sulfate
  9. filtrationfiltered
  10. customevaporated to dryness

Sources & evidence

ORD record
ord-2f49966b53f74ba8b1c8f90c62d07cf4
Source dataset
uspto-grants-1980_11
Patent number
US04234598

Reaction notes

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