Phosgene → 3-Thiophenecarboxylic acid, 4-(isocyanatosulfonyl)-5-methyl-, methyl ester

HRID 2243446Notes

Reaction equation

HRID 2243446 reaction equation
[NH2:1][S:2]([C:5]1[C:6]([C:11]([O:13][CH3:14])=[O:12])=[CH:7][S:8][C:9]=1[CH3:10])(=[O:4])=[O:3].C(N=[C:20]=[O:21])CCC.C(Cl)(Cl)=O>C1(C)C(C)=CC=CC=1>[N:1]([S:2]([C:5]1[C:6]([C:11]([O:13][CH3:14])=[O:12])=[CH:7][S:8][C:9]=1[CH3:10])(=[O:4])=[O:3])=[C:20]=[O:21]

Participants

5

Reactant 3

HCID 6371Phosgene2×HCID 8110Butyl isocyanateHCID 11299311Methyl 5-methyl-4-sulfamoylthiophene-3-carboxylate

Product 1

HCID 579578313-Thiophenecarboxylic acid, 4-(isocyanatosulfonyl)-5-methyl-, methyl esterYield 84.2%

Reagents, catalysts & solvents 1

HCID 7237O-XyleneSolvent

Procedure

23.5 g of methyl 4-(aminosulfonyl)-5-methylthiophene-3-carboxylate (1) (100 mmol) were initially charged in 250 ml of xylene. From this mixture, approx. 70 ml of xylene were distilled off on a water separator. After addition of 9.9 g of n-butyl isocyanate (100 mmol), the reaction mixture was heated to reflux. Subsequently, 24 g of phosgene were introduced over a period of 3 h at such a rate that the temperature remained at approx. 130° C. (excess phosgene was kept in the system by a phosgene condenser). For workup, the mixture was cooled to room temperature and excess phosgene was removed by passing an argon stream through. Subsequently, distillative purification was effected, in which the butyl isocyanate can be recovered. The methyl 4-(isocyanatosulfonyl)-5-methylthiophene-3-carboxylate (2) can then be recovered as a colorless solid after a distillation under reduced pressure. 22 g of the methyl 4-(isocyanatosulfonyl)-5-methylthiophene-3-carboxylate (2) were obtained (83% of theory, content: 98%, b.p.: 120° C., 0.4 mbar). The identification and the determination of content were conducted by means of derivatization with methanol to the corresponding carbamate (1H NMR (400 MHz, d6DMSO): 2.72 (s), 3.61 (s), 3.79 (s), 8.00 (s), 11.96 (s)).

Workup

  1. distillationFrom this mixture, approx. 70 ml of xylene were distilled off on a water separator
  2. temperaturethe reaction mixture was heated to reflux
  3. customremained at approx. 130° C.
  4. customwas kept in the system by a phosgene condenser
  5. customexcess phosgene was removed
  6. distillationSubsequently, distillative purification
  7. customcan be recovered
  8. customThe methyl 4-(isocyanatosulfonyl)-5-methylthiophene-3-carboxylate (2) can then be recovered as a colorless solid
  9. distillationafter a distillation under reduced pressure

Sources & evidence

ORD record
ord-4018fbfcaadf4e8babe48e4b43badfd5
Source dataset
uspto-grants-2010_03
Patent number
US07674917B2

Reaction notes

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