Benzaldehyde → 6-chloro-3-phenyl-[1,2,4]triazolo[3,4-a]phthalazine

HRID 2232220Notes

Reaction equation

HRID 2232220 reaction equation
Cl.[NH:2]([C:4]1[C:13]2[C:8](=[CH:9][CH:10]=[CH:11][CH:12]=2)[C:7]([Cl:14])=[N:6][N:5]=1)[NH2:3].[CH:15](=O)[C:16]1[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=1.C(=O)(O)[O-].[Na+].C([O-])(=O)C.[Na+].BrBr>O.C(O)C.C(O)(=O)C>[Cl:14][C:7]1[C:8]2[C:13](=[CH:12][CH:11]=[CH:10][CH:9]=2)[C:4]2=[N:2][N:3]=[C:15]([C:16]3[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=3)[N:5]2[N:6]=1

Participants

10

Reactant 6

HCID 240BenzaldehydeHCID 313Hydrochloric AcidHCID 24408BromineHCID 516892Sodium BicarbonateHCID 517045Sodium AcetateHCID 27937521-Chloro-4-hydrazinophthalazine

Product 1

HCID 15025636-chloro-3-phenyl-[1,2,4]triazolo[3,4-a]phthalazineYield 74%

Reagents, catalysts & solvents 3

HCID 176Acetic AcidSolvent2×HCID 702EthanolSolventHCID 962WaterSolvent

Conditions

Temperature
70 °C

Procedure

Concentrated HCl is gradually added to a suspension of 1-hydrazino-4-chloro-phthalazine (0.1 mole) in water (900 ml) until a clear solution is obtained. Then benzaldehyde (0.1 mole) dissolved in the smallest amount of ethanol possible, is dripped into the obtained solution which is heated to 60°/70° C. and stirred for 10 minutes. The reaction mixture is then cooled, and brought to pH 8 by the addition of aqueous sodium bicarbonate. The hydrazone which forms is recovered by filtration and crystallized from isopropanol (m.p. 174°-75° C.). This hydrazone (0.1 mole) is then suspended in acetic acid (900 ml) containing anhydrous sodium acetate (0.3 mole) and to the obtained suspension a solution of bromine (0.105 mole) in acetic acid (60 ml) is added dropwise. After vigorously stirring for 60 minutes, the reaction mixture is poured into ice-water (5 1) and the solid which separates is recovered by filtration, washed first with a diluted aqueous solution of sodium metabisulfite and then with water, and finally crystallized from isopropanol yielding the compound of the title in 74% yield. M.p. 172°-74° C. Using essentially the same procedure outlined in example 1 above, a number of other 3-substituted-6-chloro-1,2,4-triazolo[3,4-a]phthalazines are prepared having the general formula ##STR17## These compounds, as well as the hydrazone intermediates of formula ##STR18## are described in Table I below.

Workup

  1. customis obtained
  2. temperatureThe reaction mixture is then cooled
  3. filtrationThe hydrazone which forms is recovered by filtration
  4. customcrystallized from isopropanol (m.p. 174°-75° C.)
  5. stirringAfter vigorously stirring for 60 minutes
  6. filtrationthe solid which separates is recovered by filtration
  7. washwashed first with a diluted aqueous solution of sodium metabisulfite
  8. customwith water, and finally crystallized from isopropanol yielding the compound of the title in 74% yield
  9. customare prepared

Sources & evidence

ORD record
ord-dc79c2ac73fd4a8e8614dcfc6960ff66
Source dataset
uspto-grants-1988_11
Patent number
US04788186

Reaction notes

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