Benzonitrile → Ethyl 5-phenyl-1,2,4-thiadiazole-3-carboxylate

HRID 1764056Notes

Reaction equation

HRID 1764056 reaction equation
O=C1[S:6][N:5]=[C:4]([C:7]([O:9][CH2:10][CH3:11])=[O:8])O1.[C:12](#[N:19])[C:13]1[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1>>[C:13]1([C:12]2[S:6][N:5]=[C:4]([C:7]([O:9][CH2:10][CH3:11])=[O:8])[N:19]=2)[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1

Participants

3

Reactant 2

HCID 7505BenzonitrileHCID 12351252ethyl 2-oxo-2H-1,3,4-oxathiazole-5-carboxylate

Product 1

HCID 12351254Ethyl 5-phenyl-1,2,4-thiadiazole-3-carboxylateYield 33%

Procedure

A solution of 8.76 g (0.050 mol) of ethyl 2-oxo-1,3,4-oxathiazole-5-carboxylate in 180 g (35 equiv., 1.75 mol) of redistilled benzonitrile was held at reflux for 72 hours. The solution, which contained the product in 62% yield (gc assay), was concentrated under vacuum to 90° C (0.5 torr). The residue was heated with 200 ml of hexane at reflux; the supernatant was decanted, treated with charcoal, filtered, and concentrated under vacuum to 6.1 g of oil and solid. The mixture was chromatographed on 200 g of silica gel (Woelm, for dry column chromatography) with benzene. The first 500 ml of eluate contained 0.8 g of product and impurities. The next 1200 ml of eluate gave 3.82 g (33%) of pure liquid product (gc assay), which crystallized after several months, mp 32°-35° C; nD25 = 1.5937; mass spectrum m/e (rel. intensity, fragment) 234 (18, M+ ), 206 (3, M+ -C2H4), 189 (10, M+ -OEt), 135 (100, M+ -EtO2CCN), 103 (14, C6H5CN+).

Workup

  1. temperatureat reflux for 72 hours
  2. concentrationwas concentrated under vacuum to 90° C (0.5 torr)
  3. temperatureThe residue was heated with 200 ml of hexane
  4. temperatureat reflux
  5. customthe supernatant was decanted
  6. additiontreated with charcoal
  7. filtrationfiltered
  8. concentrationconcentrated under vacuum to 6.1 g of oil and solid
  9. customThe mixture was chromatographed on 200 g of silica gel (Woelm, for dry column chromatography) with benzene

Sources & evidence

ORD record
ord-95def3e133cd41cfb1601d7cb7063705
Source dataset
uspto-grants-1978_09
Patent number
US04115095

Reaction notes

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