Boron trifluoride etherate → 2-Hydroxy-4,5-dimethoxybenzoic acid

HRID 1621064Notes

Reaction equation

C[O:2][C:3]1[CH:11]=[C:10]([O:12][CH3:13])[C:9]([O:14][CH3:15])=[CH:8][C:4]=1[C:5]([OH:7])=[O:6].[Na+].[Br-].B(F)(F)F.CCOCC.[OH-].[Na+]>C(OCC)(=O)C.O>[OH:2][C:3]1[CH:11]=[C:10]([O:12][CH3:13])[C:9]([O:14][CH3:15])=[CH:8][C:4]=1[C:5]([OH:7])=[O:6]

Participants

Conditions

Temperature: 40 °C

Procedure

In 10 g of ethyl acetate were suspended 2.0 g of 2,4,5-trimethoxybenzoic acid (1a) and 1.45 g of NaBr in a stream of argon, to which 4.0 g of BF3.Et2O was then added dropwise at 25° C., followed by heat stirring at 40° C. for 3 hours. The reaction mixture was cooled with ice, to which 10 mL of water was then added dropwise at 10° C., followed by dropwise adding 7.5 g of a 25% (w/w) sodium hydroxide aqueous solution. Thereto was further added 10 mL of water before stirring, followed by filtering off insoluble inorganic matter. To the separated aqueous layer was dropwise added 3.94 g of 35% hydrochloric acid, followed by stirring for 10 minutes. The precipitated crystal was collected by filtration and washed with water. The resultant crystal was then dried under reduced pressure at 60° C. to provide 1.7 g of 2-hydroxy-4,5-dimethoxybenzoic acid (2a) at a yield of 91%.

Workup

temperatureby heat
additionwas then added dropwise at 10° C.
stirringbefore stirring
filtrationby filtering off insoluble inorganic matter
stirringby stirring for 10 minutes
filtrationThe precipitated crystal was collected by filtration
washwashed with water
customThe resultant crystal was then dried under reduced pressure at 60° C.

Sources & evidence

ORD record: ord-d751b3b38cc0401898edf1f89b9dcc42
Source dataset: uspto-grants-2014_07
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08772528B2

Reaction notes

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