1H-Benzimidazole-5-carboxylic acid

GREEN-GREY TO GREY-BROWN POWDER

To a solution of 5-Bromo-1H-benzimidazole (0.87 g, 4.4 mmol, 1.0 equiv.) in dry THF (20 mL) at 0 C was added a 2 M solution of i-PrMgCl in THF (2.2 mL, 1 equiv.) during 5 min. The clear solution was stirred at that temperature for an additional 5 min, and a 2.5 M solution of n-BuLi in hexanes (3.5 mL, 8.8 mmol, 2.0 equiv.) was added dropwise during5 min, while maintaining the temperature below 20 C. The resulting mixture was stirred at thattemperature for 0.5 h, dry CO2 (0.20 g, 4.4mmol, 1.0 equiv.) was added to 20 C. The resultingmixture was warmed to 20 C in 0.5 h and quenched with water (6 mL). After stirring the mixturebelow 20 C for 10 min, the phases were separated and the water phase was extracted one additionaltime with ethyl acetate. The resulting suspension was allowed to reach room temperature and ®teredthrough a 0.5 1 cm pad of silica gel eluted with 10 mL of ethyl acetate. The ®ltrate was concentratedand the residue was puri®ed by ash chromatography on silica gel (eluent:petroleum ether/ethylacetate = 3:1) to afford product 3g as brown solid, 0.5 g (yield: 71percent). 1H-NMR (600 MHz, DMSO) 8.43 (s, 1H), 8.26 (s, 1H), 7.87 (d, J = 8.4 Hz, 1H), 7.67 (d, J = 8.4 Hz, 1H). 13C-NMR (151 MHz, DMSO) 168.47, 144.83, 125.10, 123.74, 118.13, 115.12.Step 1: A mixture of compound 1 (520 mg, 3 mol) and 2M NaOH (5 ml) in MeOH (10 ml) and THF (10 ml) was stirred 70°C for overnight. TLC was used to monitor the reaction. The mixture was then concentrated to a residue, added water (30mL) and used citric acid to adjust PHto 5-6. Extracted with EA, the organic layer was separated, washed, dried, filtered and concentrated to get compound 4 as yellow solid (320 mg, 67percent)

A benzimidazole derivative that exhibits corrosion inhibiting properties against strong acids.

Molecular Weight:162.15
XLogP3:1.3
Hydrogen Bond Donor Count:2
Hydrogen Bond Acceptor Count:3
Rotatable Bond Count:1
Exact Mass:162.042927438
Monoisotopic Mass:162.042927438
Topological Polar Surface Area:66
Heavy Atom Count:12
Complexity:196
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes