Hydrochloric Acid → Isobutyl (S)-chroman-2-carboxylate

HRID 2257486Notes

Reaction equation

HRID 2257486 reaction equation
Cl.[O:2]1[C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[CH2:5][CH2:4][C@H:3]1[C:12]([OH:14])=[O:13]>>[O:2]1[C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[CH2:5][CH2:4][C@H:3]1[C:12]([O:14][CH2:5][CH:6]([CH3:11])[CH3:7])=[O:13]

Participants

3

Reactant 2

HCID 313Hydrochloric AcidHCID 6933105(2S)-3,4-dihydro-2H-1-benzopyran-2-carboxylic acid

Product 1

HCID 54151958Isobutyl (S)-chroman-2-carboxylate

Procedure

The aqueous phase of the hydrolysis reaction was acidified to pH of 2.0 with conc. HCl forming a white precipitate of (S)-chroman-2-carboxylic acid. The S-acid was extracted into toluene, and the phases were separated. The organic layer was placed in a vessel suitable for acid catalyzed esterification. Sulfuric acid was added to the vessel, and the mixture was heated to reflux. Water was removed by azeotropic distillation. The conversion of the acid to the ester was followed by GC analysis. Isobutyl (S)-chroman-2-carboxylate was thereby formed. Upon completion of the esterification, the sulfuric acid catalyst used in the reaction was removed by washing the reaction product with saturated sodium carbonate, and the S-carboxylate product was azeotropically dried again.

Workup

  1. customThe aqueous phase of the hydrolysis reaction
  2. extractionThe S-acid was extracted into toluene
  3. customthe phases were separated
  4. customThe organic layer was placed in a vessel suitable for acid
  5. additionSulfuric acid was added to the vessel
  6. temperaturethe mixture was heated to reflux
  7. customWater was removed by azeotropic distillation

Sources & evidence

ORD record
ord-509626b07857430d8702245ebee2df6d
Source dataset
uspto-grants-1997_08
Patent number
US05658796

Reaction notes

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