Formic Acid → 3H-1,2,4-Triazol-3-one

HRID 1651298Notes

Reaction equation

HRID 1651298 reaction equation
[NH2:1][C:2]([NH2:4])=[O:3].S(=O)(=O)(O)O.C(O)=O.[NH2:13][NH:14][C:15]([NH2:17])=[O:16]>O.C(O)=O.O>[NH2:13][NH:14][C:15]([NH2:17])=[O:16].[N:4]1[C:2](=[O:3])[N:1]=[CH:15][N:14]=1

Participants

8

Reactant 4

HCID 284Formic AcidHCID 1118Sulfuric AcidHCID 1176UreaHCID 5196Semicarbazide

Product 2

HCID 5196SemicarbazideHCID 110733393H-1,2,4-Triazol-3-oneYield 43.1%

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 18673298Formic acid--water (1/1)Solvent

Conditions

Temperature
10 °C

Procedure

Aqueous semicarbazide free base feedstock (523.8 grams) was prepared from 64 percent N2H4 (4.18 moles) and urea (4.17 moles) by the method of Example 1. Ninety-eight percent sulfuric acid (99.8 grams, 0.998 mole) and 90 percent formic acid (510.6 grams, 9.99 moles) were successively added to the aqueous semicarbazide free base. After reflux at 108°-110° C. for four hours, a formic acid/H2O azeotrope was stripped, H2O (160 ml) was added to the concentrate and stripping resumed at 118°-125° C. to give 595 grams of combined distillate. The reaction mixture was cooled to 10° C. and the mother liquor was siphoned (58 grams). Crude 1,2,4-triazol-5-one was recrystallized from H2O (725 ml), the supernatant liquid was siphoned (930 grams), and 200 ml H2O was added for product filtration. Vacuum-drying gave 152.6 grams of 1,2,4-triazol-5-one (1.80 moles, 43.1 percent yield based on N2H4 charged), m.p. 234°-236° C. (Cl-, 0.02 percent).

Workup

  1. temperatureAfter reflux at 108°-110° C. for four hours
  2. concentrationconcentrate
  3. customstripping resumed at 118°-125° C.
  4. customto give 595 grams of combined distillate
  5. customCrude 1,2,4-triazol-5-one was recrystallized from H2O (725 ml)
  6. additionwas added for product filtration
  7. customVacuum-drying

Sources & evidence

ORD record
ord-572f0ddce3984d3eb1b84e30440d33ea
Source dataset
uspto-grants-1990_05
Patent number
US04927940

Reaction notes

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