Isonicotinic acid

Isonicotinic acid or pyridine-4-carboxylic acid is an organic compound with the formula C₅H₄N(CO₂H). It is a derivative of pyridine with a carboxylic acid substituent at the 4-position. It is an isomer of picolinic acid and nicotinic acid, which have the carboxyl group at the 2- and 3-position respectively compared to the 4-position for isonicotinic acid.

Isonicotinic acid^[1]

Skeletal formula Ball-and-stick model
Names
Preferred IUPAC name Pyridine-4-carboxylic acid
Other names Isonicotinic acid 4-Pyridinecarboxylic acid p-Pyridinecarboxylic acid 4-Picolinic acid
Identifiers
CAS Number	55-22-1 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:6032 Y
ChEMBL	ChEMBL1203 Y
ChemSpider	5709 Y
ECHA InfoCard	100.000.208
KEGG	C07446 Y
PubChem CID	5922
UNII	Y8SYN761TQ Y
CompTox Dashboard (EPA)	DTXSID8020757
InChI InChI=1S/C6H5NO2/c8-6(9)5-1-3-7-4-2-5/h1-4H,(H,8,9) Y Key: TWBYWOBDOCUKOW-UHFFFAOYSA-N Y InChI=1/C6H5NO2/c8-6(9)5-1-3-7-4-2-5/h1-4H,(H,8,9) Key: TWBYWOBDOCUKOW-UHFFFAOYAV
SMILES c1cnccc1C(=O)O
Properties
Chemical formula	C6H5NO2
Molar mass	123.111 g·mol−1
Appearance	White to off-white crystalline solid
Density	Solid
Melting point	310 °C (590 °F; 583 K) (sublimes)
Hazards
NFPA 704 (fire diamond)	3 1 0
Safety data sheet (SDS)	http://datasheets.scbt.com/sc-250188.pdf
Related compounds
Related compounds	nicotinic acid, pyridine isoniazid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Production

On a commercial scale, isonicotinic acid, like other pyridine carboxylic acid is produced by ammoxidation of 4-picoline (4-methylpyridine) followed by hydrolysis of the resulting nitrile:

NC₅H₄CH₃ + 1.5 O₂ + NH₃ → NC₅H₄C≡N + 3 H₂O

NC₅H₄C≡N + 2 H₂O → NC₅H₄CO₂H + NH₃

It is also produced by oxidation of 4-picoline with nitric acid.^[2]

Derivatives

Isonicotinic acids is a term loosely used for derivatives of isonicotinic acid. Hydrazide derivatives include isoniazid, iproniazid, and nialamide. Amide and ester derivatives include ethionamide and dexamethasone isonicotinate.

Its conjugate base forms coordination polymers^[3] and MOFs^[4] by binding metal ions through both the N and carboxylate.

See also

• Pyridinecarboxylic acids