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

HRID 2118521Notes

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-afa29157c45042fc924bf6a07c78ac9b
Source dataset: uspto-grants-1987_07
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04678793

Reaction notes

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