2-Phenyl-2H-pyrazole-3(4H)-one synthesis
- Product Name:2-Phenyl-2H-pyrazole-3(4H)-one
- CAS Number:876-92-6
- Molecular formula:C9H8N2O
- Molecular Weight:160.17
88585-32-4
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Yield:876-92-6 38%
Reaction Conditions:
Stage #1: 4-ethoxycarbonyl-1-phenyl-3-pyrazolin-5-onewith sodium hydroxide;water in methanol at 70; for 7 h;
Stage #2: with hydrogenchloride in methanol;water at 0 - 100; pH=2; for 14 h;
Steps:
24.B
To a solution of 3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-carboxylic acid ethyl ester (20.5 g, 88.1 mmol) in MeOH (150 mL) was added 1 N NaOH .(220 mL, 440 mmol) and the reaction mixture was heated to 70 0C for 7 hrs. The reaction mixture was then cooled to 0 0C and concentrated HCI was added to adjust to pH = 2. The acidified reaction mixture was then heated to 100 0C for 14 hrs. Subsequently, the reaction mixture was cooled to 25 0C and ethyl acetate (400 mL) and water (200 mL) were added. The organic layer was separated, washed with brine, dried over Na2SO4 and concentrated to a brown oil that was purified by column chromatography (20-50% ethyl acetate/hexane) to provide 2-phenyl-2,4- dihydro-pyrazol-3-one (5.42 g, 38%). 1H-NMR (400 MHz, d-CDCI3) δ 7.84 (d, 2 H), 7.46 (s, 1 H)1 7.41- 7.35 (m, 2 H)1 7.21-7.17 (m, 1 H), 3.47 (s, 2 H).
References:
WO2008/23235,2008,A1 Location in patent:Page/Page column 30
25115-90-6
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706819-80-9
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100-63-0
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$10.00/1g
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