Benzoic Acid → Thiourea, (5-phenyl-1,2,4-thiadiazol-3-yl)-

HRID 379323Notes

Reaction equation

HRID 379323 reaction equation
C([NH:9][C:10](=[S:23])[NH:11][C:12]1[N:16]=[C:15]([C:17]2[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=2)[S:14][N:13]=1)(=O)C1C=CC=CC=1.[OH-].[K+].Cl.[OH-].[NH4+].C(O)(=O)C1C=CC=CC=1>>[C:17]1([C:15]2[S:14][N:13]=[C:12]([NH:11][C:10]([NH2:9])=[S:23])[N:16]=2)[CH:18]=[CH:19][CH:20]=[CH:21][CH:22]=1

Participants

6

Reactant 5

HCID 243Benzoic AcidHCID 313Hydrochloric AcidHCID 14797Potassium HydroxideHCID 14923Ammonium HydroxideHCID 11473278HCID 11473278, compound

Product 1

HCID 9837595Thiourea, (5-phenyl-1,2,4-thiadiazol-3-yl)-

Conditions

Temperature
60 °C

Procedure

3-[N′-(benzoyl)thioureido]-5-phenyl-1,2,4-thiadiazole (BzPTT; 1 kg, 2.94 moles) was placed in a 12-L reaction vessel. A solution of KOH (8.8 L; 3.0 M in water) was added with stirring. The reaction milieu (initially yellow) was heated to 60° C. for about 1 hour or until completion with vigorous stirring. Completion of the reaction was determined either by a color change, e.g., from yellow (BzPTT) to white (PTT), or by monitoring by NMR. Concentrated HCl (2.2 L) was added with stirring at 0-10° C. to lower the pH to about 2-3 by Litmus paper. Concentrated ammonium hydroxide (241 mL) was added to the reaction milieu to raise the pH to about 8, which is more than 4 pH units greater than the pKa of the benzoic acid. After cooling in an ice bath for 30 minutes, the PTT was isolated by filtration in a Büchner funnel over filter paper and dried at room temperature overnight until dryness. The yield of PTT was about 97.4% and the product was about 99.7% pure as determined by HPLC. The H1NMR and 13C NMR spectrum of the product was consistent with that of a reference sample. Mp (253-255° C.) and mass spectroscopy were also used to identify the product.

Workup

  1. stirringwith stirring at 0-10° C.
  2. temperatureto raise the pH to about 8, which
  3. temperatureAfter cooling in an ice bath for 30 minutes
  4. customthe PTT was isolated by filtration in a Büchner funnel
  5. filtrationover filter paper
  6. customdried at room temperature overnight until dryness
  7. customMp (253-255° C.) and mass spectroscopy

Sources & evidence

ORD record
ord-aa1139443c2f491591523d6fae2d6ea4
Source dataset
uspto-grants-2001_10
Patent number
US06297384B1

Reaction notes

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