3-Amino-4-fluorobenzoic acid

off-white powder

A mixture of 3-nitro-4-fluorobenzoic acid (1.85 g, 10.0 mmol) in MeOH (10 mL) and 5percent Pd/C (100 mg) was stirred under an atmosphere of hydrogen and for 6 h. The catalyst was removed by filtration, washed with methanol and the volatiles were removed in vacuo to give compound 8A, 3-amino-4-fluorobenzoic acid, as a light yellow solid (1.50 g, 9.67 mmol, 97percent).To a solution of 4-fluoro-3-nitrobenzoic acid (15.0 g, 81 mmol) in MeOH (150 mL) under an atmosphere of nitrogen was added 10percent Pd/C (0.80 g). The mixture was then stirred under 1 atm HGeneral procedure: Before each run, the system (see Fig.4) was allowed to equilibrate by pumping solvent through for 30min with the Tube-in-Tube device at 16bar of hydrogen. An omnifit cartridge (20.0mm OD, 15.0mm ID) containing 1g of Pd-C catalyst was used. To avoid an overpressure of the system in the event of blockage, the upper pressure cut-off limit on the Knauer pump was set to 25bar. With the injection loop disconnected from the flow line, the loop was opened and filled manually (using a syringe) with 3.6mL of a 0.076M solution of starting material in ethanol (excess starting material solution exiting the loop was recovered for reuse). The injection loop was then closed off and switched into the flow stream. The outlet from the system (downstream of the back-pressure regulator) was collected for 120min. The solvent was removed under reduced pressure (using a rotary evaporator followed by a 2-stage rotary vane pump) to afford the product.Following a literature procedure [2], 4-fluoro-3-nitrobenzoic acid (1.0 g, 5.4 mmol) was reduced with hydrogen in the presence of Pd/C (60 mg, 10percent on charcoal) in EtOH (10 ml) over 24 h. The reaction mixture was passed through Celite, the filtrate was evaporated, and the residue was purified on a silica gel plug (EtOAc) to give 0.75 g (90percent yield) of 3-amino-4-fluorobenzoic acid as a white solid.

Molecular Weight:155.13
XLogP3:1
Hydrogen Bond Donor Count:2
Hydrogen Bond Acceptor Count:4
Rotatable Bond Count:1
Exact Mass:155.03825660
Monoisotopic Mass:155.03825660
Topological Polar Surface Area:63.3
Heavy Atom Count:11
Complexity:163
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes