Pyridoxal is one form of vitamin B₆.

Pyridoxal

Idealised skeletal formula
Ball-and-stick model based on the crystal structure.[1][2] Note that the acidic phenol group has donated a proton to the basic pyridine group to form a zwitterion, and the hydroxymethyl group has reacted with the aldehyde group to form a hemiacetal.
Names
Preferred IUPAC name 3-Hydroxy-5-(hydroxymethyl)-2-methylpyridine-4-carbaldehyde
Identifiers
CAS Number	66-72-8 Y 65-22-5 (hydrochloride) Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:17310 Y
ChEMBL	ChEMBL102970 Y
ChemSpider	1021 Y
DrugBank	DB00147 Y
ECHA InfoCard	100.000.573
KEGG	C00250 Y
PubChem CID	1050
UNII	3THM379K8A Y 1416KF0QBC (hydrochloride) Y
CompTox Dashboard (EPA)	DTXSID4046020
InChI InChI=1S/C8H9NO3/c1-5-8(12)7(4-11)6(3-10)2-9-5/h2,4,10,12H,3H2,1H3 Y Key: RADKZDMFGJYCBB-UHFFFAOYSA-N Y InChI=1/C8H9NO3/c1-5-8(12)7(4-11)6(3-10)2-9-5/h2,4,10,12H,3H2,1H3 Key: RADKZDMFGJYCBB-UHFFFAOYAP
SMILES O=Cc1c(O)c(C)ncc1CO
Properties
Chemical formula	C8H9NO3
Molar mass	167.16 g/mol
Melting point	165 °C (329 °F; 438 K) (decomposes)
Related compounds
Related arylformaldehydes	Damnacanthal Gossypol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Some medically relevant bacteria, such as those in the genera Granulicatella and Abiotrophia, require pyridoxal for growth. This nutritional requirement can lead to the culture phenomenon of satellite growth. In in vitro culture, these pyridoxal-dependent bacteria may only grow in areas surrounding colonies of bacteria from other genera ("satellitism") that are capable of producing pyridoxal.

Pyridoxal is involved in what is believed to be the most ancient reaction of aerobic metabolism on Earth, about 2.9 billion years ago, a forerunner of the Great Oxidation Event.^[3]