4-chlorobenzohydrazide

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a mixture of 4-chlorobenzohydrazide 5 (1 g, 5.86 mmol) and K2CO3 (0.97 g, 7.03 mmol) in acetonitrile (30 mL) was added 2-chloroacetyl chloride (0.68 g, 6.08 mmol) dropwise at ambient temperature. The resulting mixture was stirred at ambient temperature for 16 hours. The solid was collected, washed with H2O and ether, and dried to afford 4-chloro-N′-(2-chloroacetyl)benzohydrazide 6 (1.2 g, 82%) which was used for the next step without further purification. A mixture of 4-chloro-N′-(2-chloroacetyl)benzohydrazide 6 (0.6 g, 2.43 mmol) and phosphorous oxychloride (0.37 g, 2.43 mmol) in acetonitrile (20 mL) was stirred under reflux for 16 hours and concentrated. The residue was subjected to flush column chromatography eluting with 10-25% acetone/hexanes to give compound 7 (0.45 g). Yield: 82%. The solid was collected washed with H2O and ether dried

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:10.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a suspension of 4-chlorobenzhydrazide (98.5 g, 0.05 mole) in tetrahydrofuran (100 ml) at room temperature ethylisocyanate (4.2 g, 0.05 mole) was added slowly with magnetic stirring. The reaction was slightly exothermic and the reaction mixture turned to a thick paste. Stirring was continued an additional 30 min after which the solid was collected by suction-filtration and washed with a small amount of tetrahydrofuran and dried to provide 11.6 g (96.6% yield), of 1-(4-chlorobenzoyl)-4-ethyl semicarbazide as a white solid., m.p.=242°-243° C. The above semicarbazide (10 g, 0.0414 mole) was dissolved in 1N sodium hydroxide solution (100 ml) and was refluxed with stirring for 16 hr. The solution was cooled down to about 10° C. by an ice bath and was neutralized by conc. hydrogen chloride until pH 2. The resultant white solid was collected by suction-filtration and washed with water to give 8.65 g (93.5% yield) of 3-(4-chlorophenyl)-4-ethyl-1,2,4-triazolin-5-one as a white solid. m.p.=190°-197° C. A proton NMR spectrum was consistent with the desired structure. was added slowly with magnetic stirring after which the solid was collected by suction-filtration washed with a small amount of tetrahydrofuran dried to provide 11.6 g (96.6% yield) was refluxed with stirring for 16 hr The resultant white solid was collected by suction-filtration washed with water

Conditions: temp:10.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a suspension of 4-chlorobenzhydrazide (98.5 g, 0.05 mole) in tetrahydrofuran (100 ml) at room temperature ethylisocyanate (4.2 g, 0.05 mole) was added slowly with magnetic stirring. The reaction was slightly exothermic and the reaction mixture turned to a thick paste. Stirring was continued an additional 30 min after which the solid was collected by suction-filtration and washed with a small amount of tetrahydrofuran and dried to provide 11.6 g (96.6% yield), of 1-(4-chlorobenzoyl)-4-ethyl semicarbazide as a white solid., m.p.=242°-243° C. The above semicarbazide (10 g, 0.0414 mole) was dissolved in 1N sodium hydroxide solution (100 ml) and was refluxed with stirring for 16 hr. The solution was cooled down to about 10° C. by an ice bath and was neutralized by conc. hydrogen chloride until pH 2. The resultant white solid was collected by suction-filtration and washed with water to give 8.65 g (93.5% yield) of 3-(4-chlorophenyl)-4-ethyl-1,2,4-triazolin-5-one as a white solid. m.p.=190°-197° C. A proton NMR spectrum was consistent with the desired structure. was added slowly with magnetic stirring after which the solid was collected by suction-filtration washed with a small amount of tetrahydrofuran dried to provide 11.6 g (96.6% yield) was refluxed with stirring for 16 hr The resultant white solid was collected by suction-filtration washed with water

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To the suspension of 4-chlorobenzhydrazide (8.53 g, 0.05 mole) in methylene chloride (100 ml), equipped with a magnetic stirring bar, a nitrogen inlet, a dropping funnel, and an outlet connected to diluted base solution for trapping the HCl gas, was dropwise added trichloromethyl chloroformate (5.94 g, 0.03 mole). After addition, the reaction mixture was heated to reflux for 2 hr. The reaction was cooled down to room temperature and poured into a mixture of water (500 ml) and hexane (200 ml) and stirred for 10 to 20 min. The resultant precipitate was collected by suction-filtration and was washed with hexane to give a solid product. The product was dried in air at room temperature overnight yielding 5.5 g (60% yield) of 2-(4-chlorophenyl)-1,3,4-oxadiazolin-5-one as a solid, m.p.=225°-227° C. NMR and IR spectra showed the desired structure. Without further purification, this product was subjected to the next step. equipped with a magnetic stirring bar, a nitrogen inlet, a dropping funnel, and an outlet to diluted base solution After addition the reaction mixture was heated to reflux for 2 hr The resultant precipitate was collected by suction-filtration was washed with hexane to give a solid product The product was dried in air at room temperature overnight