Monosodium hydrogen 4-chlorophthalate → 4-Chlorophthalic anhydride

HRID 1402838Notes

Reaction equation

HRID 1402838 reaction equation
[Na+].[Cl:2][C:3]1[CH:4]=[C:5]([C:12]([OH:14])=[O:13])[C:6](=[CH:10][CH:11]=1)[C:7]([O-:9])=O>S(Cl)(Cl)=O>[Cl:2][C:3]1[CH:4]=[C:5]2[C:12](=[O:13])[O:14][C:7](=[O:9])[C:6]2=[CH:10][CH:11]=1

Participants

3

Reactant 1

HCID 23687624Monosodium hydrogen 4-chlorophthalate

Product 1

HCID 670444-Chlorophthalic anhydrideYield 64.3%

Reagents, catalysts & solvents 1

HCID 24386Thionyl ChlorideSolvent

Procedure

The mixture of commercial 4-chlorophthalic acid monosodium salt (40 g) and thionyl chloride (50 ml) was stirred under reflux for 2 h. From the resulting viscous mass all volatiles were removed at the water aspirator. The residue was heated with benzene (150 ml) and the still hot slurry was filtered by suction. The filter cake was washed twice with benzene (50 ml) and the filtrate was concentrated in vacuo to give a yellowish solid. The crude was recrystallised from n-hexane/benzene 3:1 (filtration of the boiling solution needed) to yield 4-chlorophthalic anhydride (21.1 g) as colourless crystals.

Workup

  1. temperatureunder reflux for 2 h
  2. customFrom the resulting viscous mass all volatiles were removed at the water
  3. temperatureThe residue was heated with benzene (150 ml)
  4. filtrationthe still hot slurry was filtered by suction
  5. washThe filter cake was washed twice with benzene (50 ml)
  6. concentrationthe filtrate was concentrated in vacuo
  7. customto give a yellowish solid
  8. customThe crude was recrystallised from n-hexane/benzene 3:1 (
  9. filtrationfiltration of the boiling solution

Sources & evidence

ORD record
ord-d2d50242b8054b4a8d7082d3cdb56a4e
Source dataset
uspto-grants-2014_12
Patent number
US08912186B2

Reaction notes

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