Hydrogen Bromide → 1,3,4-Thiadiazole-2,5-dione

HRID 437773Notes

Reaction equation

HRID 437773 reaction equation
C(Cl)(Cl)=O.O(C)C([S-])=S.[K+].NN.[CH3:13][O:14][C:15]1[S:16][C:17](=[O:20])[NH:18][N:19]=1.Br>C(O)(=O)C>[CH3:13][O:14][C:15]1[S:16][C:17](=[O:20])[NH:18][N:19]=1.[S:16]1[C:17](=[O:20])[N:18]=[N:19][C:15]1=[O:14]

Participants

8

Reactant 5

HCID 260Hydrogen BromideHCID 6371PhosgeneHCID 9321HydrazineHCID 1929405-Methoxy-1,3,4-thiadiazol-2(3H)-oneHCID 11309586Potassium methylxanthate

Product 2

HCID 1929405-Methoxy-1,3,4-thiadiazol-2(3H)-oneHCID 129996461,3,4-Thiadiazole-2,5-dioneYield 168.5%

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent

Procedure

2-Methoxy-1,3,4-thiadiazol-5(4H)-one (7) was prepared from phosgene, potassium methyl xanthate, and hydrazine according to the method of K. Rufenacht, Helv. Chim. Acta, 51, 518 (1968). This was hydrolyzed to 1 by the following procedure. A mixture of 50 g of thiadiazole 7 in 300 ml of acetic acid was warmed to 80° to effect solution and then cooled to 70°, whereupon HBr gas was bubbled rapidly into the solution for 25 min. The HBr was shut off, the mixture was held at 70° for 35 min, and then it was cooled to 10°. Ether (200 ml) was added and the mixture was cooled back to 10°. The mixture was filtered through sintered glass and the filter cake was washed with ether, giving 37 g (75%) of 1,3,4-thiadiazoline-2,5-dione or 2-hydroxy-1,3,4-thiadiazol-5-(4H)-one (1). A thirty-gram sample was crystallized from 300 ml of ethanol, affording 18 g of pure 2, mp 175°-255°, infrared maxima (IR), νmax 1700 and 1680 cm-1, ultraviolet maxima (UV), λmax (EtOH) 235 nm (ε 3000) and λmax (EtOH+ NaOH), 258 nm (ε 2730), high resolution mass spectrum (HRMS), m/e calculated for C2H2N2O2S (M+): 117.9837; measured: 117.9825.

Workup

  1. temperaturewas warmed to 80°
  2. customwas bubbled rapidly into the solution for 25 min
  3. temperatureit was cooled to 10°
  4. additionEther (200 ml) was added
  5. temperaturethe mixture was cooled back to 10°
  6. filtrationThe mixture was filtered through sintered glass
  7. washthe filter cake was washed with ether

Sources & evidence

ORD record
ord-1bfabdb7165e4a99816ac2c3a9d0310e
Source dataset
uspto-grants-1977_06
Patent number
US04032533

Reaction notes

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