Phosphorus pentachloride → 3-Chlorothiophene-2-carboxylic acid

HRID 904339Notes

Reaction equation

HRID 904339 reaction equation
P(Cl)(Cl)(Cl)(Cl)[Cl:2].O[C:8]1[CH:12]=[CH:11][S:10][C:9]=1[C:13]([O:15]C)=[O:14]>C(Cl)(Cl)(Cl)Cl>[Cl:2][C:8]1[CH:12]=[CH:11][S:10][C:9]=1[C:13]([OH:15])=[O:14]

Participants

4

Reactant 2

HCID 24819Phosphorus pentachlorideHCID 5811273-Hydroxy-thiophene-2-carboxylic acid methyl ester

Product 1

HCID 7012693-Chlorothiophene-2-carboxylic acid

Reagents, catalysts & solvents 1

HCID 5943Carbon TetrachlorideSolvent2×

Procedure

52.1 g of phosphorus pentachloride are dissolved in 600 ml of absolute carbon tetrachloride and heated to boiling, whereupon a solution of 15.8 g of 3-hydroxy-2-methoxycarbonylthiophene in 200 ml of carbon tetrachloride is added dropwise during 3 hours. The mixture is boiled to reflux for 13 hours, the carbon tetrachloride is distilled off and the mixture is evaporated almost to dryness in vacuo. 450 ml of water are added dropwise while cooling, whereupon the mixture is heated to boiling and then allowed to cool. The resulting precipitate is filtered off under suction and boiled up with 10 g of active carbon in a solution of 25 g of sodium bicarbonate. The active carbon is then filtered off under suction and the cooled solution is acidified with hydrochloric acid. There is obtained 3-chlorothiophene-2-carboxylic acid of melting point 185°-186° C.

Workup

  1. temperatureheated
  2. additionis added dropwise during 3 hours
  3. temperatureto reflux for 13 hours
  4. distillationthe carbon tetrachloride is distilled off
  5. customthe mixture is evaporated almost to dryness in vacuo
  6. addition450 ml of water are added dropwise
  7. temperaturewhile cooling, whereupon the mixture
  8. temperatureis heated
  9. temperatureto cool
  10. filtrationThe resulting precipitate is filtered off under suction
  11. filtrationThe active carbon is then filtered off under suction

Sources & evidence

ORD record
ord-855b0b5212324e17bbb3f30a612c1475
Source dataset
uspto-grants-1980_10
Patent number
US04230873

Reaction notes

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