3,5-DIFLUORO-2-NITROBENZOIC ACID synthesis
- Product Name:3,5-DIFLUORO-2-NITROBENZOIC ACID
- CAS Number:331765-71-0
- Molecular formula:C7H3F2NO4
- Molecular Weight:203.1
455-40-3
331765-71-0
Step 1: 3,5-difluorobenzoic acid (80 g, 506 mmol) was stirred with concentrated sulfuric acid (250 mL) for 1 hour at room temperature. Subsequently, concentrated nitric acid (90 mL) was added slowly and dropwise while the reaction temperature was controlled below 45 °C by a water bath. The reaction mixture was stirred overnight at room temperature. The reaction was quenched by slowly pouring the reaction solution into crushed ice, the precipitated solid was collected by filtration and washed thoroughly with cold water to afford 3,5-difluoro-2-nitrobenzoic acid (compound 273) as a white solid (93.0 g, 91% yield). The product could be used directly in the subsequent reaction without further purification.1H NMR (400 MHz, DMSO-d6) δ 8.01 (ddd, J = 10.9, 8.5, 2.8 Hz, 1H), 7.71 (dt, J = 8.4, 2.2 Hz, 1H).
455-40-3
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Yield:331765-71-0 91%
Reaction Conditions:
Stage #1: 3,5-difluorobenzoic acidwith sulfuric acid at 20; for 1 h;
Stage #2: with nitric acid at 20 - 45;
Steps:
Step 1 : 3,5-difluorobenzoic acid (80 g, 506 mmol) and sulfuric acid ( 250 ml) were stirred at room temperature for one hour. Then nitric acid (90 ml) was added, keeping the internal temperature below 45C with a water bath. The mixture was left at room temperature overnight. The reaction was poured slowly into ice and the resulting solid was filtered and washed with cold water to give compound 273 as a white solid (93.0 g, 91 % yield). This material was taken into the next step without further purification. 1H NMR (400 MHz, DMSO-d6) δ 8.01 (ddd, J=10.9, 8.5, 2.8 Hz, 1 H), 7.71 ( dt, J= 8.4, 2.2 Hz, 1 H).
References:
WO2013/132376,2013,A1 Location in patent:Page/Page column 234