The IUPAC name of Coumarin-3-carboxylic acid is 2-oxochromene-3-carboxylic acid . With the CAS registry number 531-81-7, it is also named as 2-Oxobenzopyran-3-carboxylic acid ; 3-Carboxycoumarin ; 5-18-08-00323 (Beilstein Handbook Reference) ; AI3-36066 ; G 1 (The rodenticide) (VAN) ; Malonic acid, salicylidene-, delta-lactone ; 2-Oxo-2H-chromene-3-carboxylic acid ; 2H-1-Benzopyran-3-carboxylic acid, 2-oxo- . It is a pharmaceutical intermediate. Coumarin-3-carboxylic acid was used as a detector for hydroxyl radicals (.OH) in aqueous solution. This method is quantitative, sensitive, specific and therefore accurate. It has an excellent potential for use in biological systems.

The Coumarin-3-carboxylic acid can be obtained in high yields with excellent purity from ortho-hydroxybenzaldehydes and Meldrum's acid after a 2 h reflux in ethanol. It is also prepared by 2-oxo-2H-chromene-3-carboxylic acid ethyl ester , 2-hydroxy-benzaldehyde and malonic acid .

The Coumarin-3-carboxylic acid can be used in many organic synthesis. For example: 1. It reacts with 5,6-diamino-3-methyl-1-phenyl-1H-pyrimidine-2,4-dione to get 2-oxo-2H-chromene-3-carboxylic acid (6-amino-3-methyl-2,4-dioxo-1-phenyl-1,2,3,4-tetrahydro-pyrimidin-5-yl)-amide . 2. It reacts with 3-amino-4-hydroxy-chromen-2-one to obtain 2-(3-coumarinyl)-coumarino(3',4':4,5)oxazole .

The Coumarin-3-carboxylic acid is toxic if swallowed. If you want to contact the product, you must wear suitable protective clothing, gloves and eye/face protection. After contact with skin, wash immediately with plenty of soap-suds. In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) 

The other characteristics of this product can be summarized as: (1)#H bond acceptors: 4 ; (2)#H bond donors: 1 ; (3)#Freely Rotating Bonds: 1 ; (4)Index of Refraction: 1.639 ; (5)Molar Refractivity: 45.86 cm³ ; (6)Molar Volume: 127.3 cm³ ; (7)Polarizability: 18.18×10^-24 cm³ ; (8)Surface Tension: 66.8 dyne/cm ; (9)Enthalpy of Vaporization: 67.28 kJ/mol ; (10)Vapour Pressure: 9.77E-07 mmHg at 25°C. People can use the following data to convert to the molecule structure. SMILES: O=C(O)C\1=C\c2c(OC/1=O)cccc2; InChI: InChI=1/C10H6O4/c11-9(12)7-5-6-3-1-2-4-8(6)14-10(7)13/h1-5H,(H,11,12).

The following is the toxicity data which has been tested.