Sulfuric Acid → 3,4-dihydro-2H-1-benzopyran-2-carboxylic acid

HRID 988842Notes

Reaction equation

HRID 988842 reaction equation
C([C:5]1[CH:6]=[C:7]2[C:12](=[C:13](C(C)(C)C)[CH:14]=1)[O:11][CH:10]([C:19]([OH:21])=[O:20])[CH2:9][CH2:8]2)(C)(C)C.[Cl-].[Al+3].[Cl-].[Cl-].S(=O)(=O)(O)O>C1(C)C=CC=CC=1>[O:11]1[C:12]2[C:7](=[CH:6][CH:5]=[CH:14][CH:13]=2)[CH2:8][CH2:9][CH:10]1[C:19]([OH:21])=[O:20]

Participants

5

Reactant 3

HCID 1118Sulfuric AcidHCID 6451240Aluminum(III) ChlorideHCID 99658046,8-Di-t-butyl-2-hydroxycarbonylchroman

Product 1

HCID 27236653,4-dihydro-2H-1-benzopyran-2-carboxylic acidYield 90%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent2×

Procedure

6,8-di-t-Butyl-2-hydroxycarbonylchroman (2.90 g, 0.01 mol) obtained in Example 3 was dissolved in toluene (27 g), and the resulting solution was added dropwise to a suspension of aluminum chloride (2.67 g, 0.02 mol) in toluene at room temperature. After the dropwise addition, the mixture was stirred at room temperature for 2 h. The reaction mixture was poured into aqueous sulfuric acid solution and the organic layer was separated. An aqueous alkaline solution was added to the organic layer and the aqueous layer was separated. An aqueous sulfuric acid solution was added to the aqueous layer and the mixture was extracted with toluene. The extract was concentrated under reduced pressure. The residue was quantitatively analyzed by liquid chromatography according to the internal standard method. As a result, 2-chroman-carboxylic acid was obtained in a yield of 90% [net 1.60 g, 0.009 mol]. The 1H-NMR data of the obtained 2-chroman-carboxylic acid are shown below.

Workup

  1. additionAfter the dropwise addition
  2. customthe organic layer was separated
  3. additionAn aqueous alkaline solution was added to the organic layer
  4. customthe aqueous layer was separated
  5. additionAn aqueous sulfuric acid solution was added to the aqueous layer
  6. extractionthe mixture was extracted with toluene
  7. concentrationThe extract was concentrated under reduced pressure

Sources & evidence

ORD record
ord-a7734a90866c40e4a89deb18d68c6e35
Source dataset
uspto-grants-2003_10
Patent number
US06635772B2

Reaction notes

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