2-Hydroxycinchoninic acid

Solid

2-oxo-1,2-dihydroquinoline-4-carboxylic acid is a quinolinemonocarboxylic acid. It is a conjugate acid of a 2-oxo-1,2-dihydroquinoline-4-carboxylate.

400 kg of recovered glacial acetic acid was placed in a 1000 L reactor and 100 kg of isatin, 160 kg of malonic acid, and 15 kg of sodium acetate were added under stirring. The mixture was heated to reflux and refluxed for 6 hours. After the reaction is completed, the acetic acid is distilled off under reduced pressure. 300 kg of deionized water are added to stir the crystals. The filtered solids are first washed with cold 30 kg glacial acetic acid and then rinsed with cold 30 kg methanol to obtain 2-hydroxy-. 4-Carboxyquinoline wet product, after filtering and drying at 45-70°C for 24 hours, 125 kg of 2-hydroxy-4-carboxyquinoline was obtained with a yield of 97.3percent and a liquid phase purity of 99.6percent.A stirred suspension of isatin, also called 1H-indole-2, 3-dione, available from Sigma-Aldrich, (3.80 g, 25 mmol) and malonic acid (8.06 g, 77 mmol) in acetic acid (150 ml) was refluxed for 16 h. Acetic acid was removed under reduced pressure, the residue was suspended in water (150 ml), filtered and washed with water (100 ml) to give a brown solid. The solid was stirred in NaHCO3 saturated aqueous solution (200 ml) and the insoluble material was filtered off. The filtrate was acidified to pH 1-2 withconcentrated HCl and the precipitate was filtered, washed with water and dried to obtainthe desired product as a grey solid (2.2 g, 11.6 mmol, Yield 40percent). 1H NMR (500 MHz; d6-DMSO) δ 6.87 (5, 1H), 7.23 (ddd, 1H, J= 1.2 Hz, J= 7.2 Hz, J=8.3 Hz), 7.41 (dd, 1H, J= 0.7 Hz, J= 8.3 Hz), 7.55 (ddd, 1H, J= 1.4 Hz, J= 7.2 Hz, J=8.4 Hz), 8.15 (dd, 1H, J= 1.2 Hz, J= 8.3 Hz), 12.13 (brs, 1H) ppm. Purity by LCMS (UV Chromatogram, 190-450nm) 90percent, rt = 2.96 min m/z 190 (M+H)+Preparation 10

Cincocaine intermediate

Molecular Weight:189.17
XLogP3:0.6
Hydrogen Bond Donor Count:2
Hydrogen Bond Acceptor Count:3
Rotatable Bond Count:1
Exact Mass:189.042593085
Monoisotopic Mass:189.042593085
Topological Polar Surface Area:66.4
Heavy Atom Count:14
Complexity:309
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes