Hydrochloric Acid → 1,3-Dihydroisobenzofuran

HRID 1659599Notes

Reaction equation

HRID 1659599 reaction equation
[H-].[Al+3].[Li+].[H-].[H-].[H-].[CH:7]1[CH:8]=[CH:9][C:10]2[C:16](C3C=CC(O)=CC=3)(C3C=CC(O)=CC=3)[O:15][C:13](=O)[C:11]=2[CH:12]=1.C(OCC)(=O)C.Cl>O1CCCC1.O>[CH2:13]1[O:15][CH2:16][C:10]2[C:11]1=[CH:12][CH:7]=[CH:8][CH:9]=2

Participants

7

Reactant 4

HCID 313Hydrochloric AcidHCID 4764PhenolphthaleinHCID 8857Ethyl AcetateHCID 21226445Aluminium lithium hydride2×

Product 1

HCID 103271,3-Dihydroisobenzofuran

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 8028TetrahydrofuranSolvent2×

Procedure

Lithium aluminum hydride (3.0 g) and 100 ml of dry tetrahydrofuran were placed in a 3-neck flask equipped with a mechanical stirrer, condenser with a nitrogen inlet and addition funnel. Phenolphthalein (6.4 g) dissolved in 300 ml of dry tetrahydrofuran was added dropwise to the stirred lithium aluminum hydride suspension at a rate to maintain a gentle reflux. When addition was complete, the reaction mixture was stirred for six hours at reflux by heating with an oil bath and then allowed to stand overnight. To the stirred solution was added excess ethyl acetate followed by 500 ml of water. The pH was adjusted to approximately 2 with conc. HCl and the solution extracted with two 500 ml portions of ether. The ether layer was washed six times with 10% aqueous potassium carbonate (each time the base layer was magenta), and then evaporated to dryness to leave an off-white solid (4.5 g crude yield). The solid was crystallized from 440 ml of 20% ethanol and dried in vacuo at 60° C. to give the corresponding phthalan as very light yellow crystals (yield 3.3 g; melting range 195°-197.5° C.). TLC using ether-silica gel gave one spot. Nmr did not show methine H and was more consistent with the cyclic ether (phenolphthalan) than the open form (phenolphthalol).

Workup

  1. customequipped with a mechanical stirrer, condenser with a nitrogen inlet and addition funnel
  2. temperatureto maintain a gentle reflux
  3. additionWhen addition
  4. temperatureat reflux
  5. temperatureby heating with an oil bath
  6. waitto stand overnight
  7. extractionthe solution extracted with two 500 ml portions of ether
  8. washThe ether layer was washed six times with 10% aqueous potassium carbonate (each time the base layer
  9. customthen evaporated to dryness
  10. customto leave
  11. customan off-white solid (4.5 g crude yield)
  12. customThe solid was crystallized from 440 ml of 20% ethanol
  13. customdried in vacuo at 60° C.

Sources & evidence

ORD record
ord-854d916f93ef40b491abcb994d65c6eb
Source dataset
uspto-grants-1981_12
Patent number
US04304833

Reaction notes

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