Sulfuric Acid → 3-Methyl-2-(p-fluorophenyl)crotonic acid

HRID 1416084Notes

Reaction equation

HRID 1416084 reaction equation
[F:1][C:2]1[CH:7]=[CH:6][C:5]([CH:8]([C:12](O)([CH3:14])[CH3:13])[C:9]([OH:11])=[O:10])=[CH:4][CH:3]=1.S(=O)(=O)(O)O>C(Cl)Cl>[F:1][C:2]1[CH:3]=[CH:4][C:5]([C:8](=[C:12]([CH3:14])[CH3:13])[C:9]([OH:11])=[O:10])=[CH:6][CH:7]=1

Participants

4

Reactant 2

HCID 1118Sulfuric AcidHCID 109548534-Fluoro-α-(1-hydroxy-1-methylethyl)benzeneacetic acid

Product 1

HCID 110197243-Methyl-2-(p-fluorophenyl)crotonic acidYield 99.1%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

A solution of 96.5 g of 2-(p-fluorophenyl)-3-hydroxy-3-methylbutyric acid in 200 ml of CH2Cl2 was cooled in an ice bath and then treated dropwise with 240 g of conc. sulphuric acid within 30 minutes, with the temperature being held at ≤20°. The CH2Cl2 was then removed to 20° on a rotary evaporator. The yellowish solution was stirred at 20° for a further 45 minutes and then poured into 1 kg of ice/water mixture while stirring well. The white precipitate was filtered off under suction, washed 3 times with 100 ml of water each time and twice with 100 ml of hexane each time and finally dried in a drying oven at 40° for 16 hours and at 100° for 2 hours. There were obtained 87.5 g of 2-(p-fluorophenyl)-3-methylcrotonic acid as a white powder of m.p. 124-126°; GC purity 99.9%; yield 95.6% based on p-fluorophenylacetic acid.

Workup

  1. custombeing held at ≤20°
  2. customThe CH2Cl2 was then removed to 20° on a rotary evaporator
  3. additionpoured into 1 kg of ice/water mixture
  4. stirringwhile stirring well
  5. filtrationThe white precipitate was filtered off under suction
  6. washwashed 3 times with 100 ml of water each time
  7. dry with materialtwice with 100 ml of hexane each time and finally dried in a drying oven at 40° for 16 hours and at 100° for 2 hours

Sources & evidence

ORD record
ord-3c58e459d62f4bf3a0066bf19e7486b6
Source dataset
uspto-grants-1999_06
Patent number
US05910606

Reaction notes

Loading…