Sulfuric Acid → (E)-p-(2-(4,4-Dimethylchroman-6-yl)propenyl)benzoic acid

HRID 2232465Notes

Reaction equation

[CH3:1][C:2]1([CH3:26])[C:11]2[C:6](=[CH:7][CH:8]=[C:9](/[C:12](/[CH3:25])=[CH:13]/[C:14]3[CH:24]=[CH:23][C:17]([C:18]([O:20]CC)=[O:19])=[CH:16][CH:15]=3)[CH:10]=2)[O:5][CH2:4][CH2:3]1.[OH-].[K+].S(=O)(=O)(O)O>C(O)C.O>[CH3:1][C:2]1([CH3:26])[C:11]2[CH:10]=[C:9](/[C:12](/[CH3:25])=[CH:13]/[C:14]3[CH:15]=[CH:16][C:17]([C:18]([OH:20])=[O:19])=[CH:23][CH:24]=3)[CH:8]=[CH:7][C:6]=2[O:5][CH2:4][CH2:3]1

Participants

Conditions

Temperature: 50 °C

Procedure

4.0 g of ethyl p-[(E)-2-(4,4-dimethyl-6-chromanyl)-propenyl]benzoate were dissolved in 80 ml of ethanol and the solution obtained was treated with a solution of 5.6 g of potassium hydroxide in 20 ml of water and 20 ml of ethanol. After stirring at 50° C. for 3 hours, the mixture was cooled, poured into ice/water, acidified with 2N sulphuric acid and extracted repeatedly with ethyl acetate. The organic phase was washed with water, dried over sodium sulphate and evaporated. After recrystallization of the residue from methylene chloride/hexane, there was obtained 3.4 g of p-[(E)-2-(3,4-dihydro-4,4-dimethyl-2H-1-benzopyran-6-yl)propenyl]benzoic acid in the form of colorless crystals of melting point 196°-197° C.

Workup

customthe solution obtained
temperaturethe mixture was cooled
extractionextracted repeatedly with ethyl acetate
washThe organic phase was washed with water
dry with materialdried over sodium sulphate
customevaporated
customAfter recrystallization of the residue from methylene chloride/hexane

Sources & evidence

ORD record: ord-c748d5064ccf4a53af97b65fa2693533
Source dataset: uspto-grants-1988_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04788213

Reaction notes

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