Water → 5-Bromothiophene-2,3-dicarboxylic acid
Reaction equation
[Br:1][C:2]1[S:6][C:5]([C:7]([OH:9])=[O:8])=[C:4]([CH3:10])[CH:3]=1.[OH-:11].[Na+].[Mn]([O-])(=O)(=O)=O.[K+].[OH2:19]>>[Br:1][C:2]1[S:6][C:5]([C:7]([OH:9])=[O:8])=[C:4]([C:10]([OH:19])=[O:11])[CH:3]=1Participants
Conditions
- Temperature
- 80 °C
Procedure
A suspension of 5-bromo-3-methyl-thiophene-2-carboxylic acid (177 g, 0.80 mol), example 1-b, and sodium hydroxide (720 g, 18 mol) in 3 L of water was heated to 80° C. Potassium permanganate (513 g, 3.25 mol) was added in 25 g portions to the warm solution over 2-3 hours. The resultant suspension was heated to reflux temperature for 2 hours and then cooled to room temperature. The solid was filtered off and washed twice with 1 N NaOH and twice with water. The aqueous solution was acidified to pH <3 with concentrated sulfuric acid. The resulting white precipitate was collected on a medium fritted glass filter, washed twice with cold water, and dried under high vacuum to produce 112 g of a white solid. MS: (−) m/z 248.91, 250.98 (M−1, 79Br/81Br)
Workup
- temperatureto reflux temperature for 2 hours
- temperaturecooled to room temperature
- filtrationThe solid was filtered off
- washwashed twice with 1 N NaOH and twice with water
- customThe resulting white precipitate was collected on a medium fritted glass
- filtrationfilter
- washwashed twice with cold water
- customdried under high vacuum
Sources & evidence
- ORD record
- ord-db4af5d59b8d436bb09e986413989b32
- Source dataset
- uspto-grants-2014_04
- Patent number
- US08703795B2
Reaction notes
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