Title: Pyridoxal
CAS Registry Number: 66-72-8
CAS Name: 3-Hydroxy-5-(hydroxymethyl)-2-methyl-4-pyridinecarboxaldehyde
Additional Names: 3-hydroxy-5-(hydroxymethyl)-2-methylisonicotinaldehyde; 2-methyl-3-hydroxy-4-formyl-5-hydroxymethylpyridine
Molecular Formula: C8H9NO3
Molecular Weight: 167.16
Percent Composition: C 57.48%, H 5.43%, N 8.38%, O 28.71%
Literature References: Synthesis and structure: Harris et al., J. Biol. Chem. 154, 315 (1944); J. Am. Chem. Soc. 66, 2088 (1944).
Derivative Type: Hydrochloride
Molecular Formula: C8H9NO3.HCl
Molecular Weight: 203.62
Percent Composition: C 47.19%, H 4.95%, N 6.88%, O 23.57%, Cl 17.41%
Properties: Rhombic crystals, mp approx 165° with decompn. Soluble in water (1 g/2 ml); sol in 95% ethanol (1.7 g/100 ml); pH of 1% water soln = 2.65. The water solns are sensitive to heat. uv max: 292.5 nm (E mol 7600). Can be reduced to pyridoxine hydrochloride (mp 206-208°).
Melting point: mp approx 165° with decompn; Can be reduced to pyridoxine hydrochloride (mp 206-208°)
Absorption maximum: uv max: 292.5 nm (E mol 7600)
Derivative Type: Monoethylacetal hydrochloride
Additional Names: 1,3-Dihydro-1-ethoxy-6-methylfuro[3,4-c]pyridin-7-ol hydrochloride
Molecular Formula: C10H14ClNO3
Molecular Weight: 231.68
Percent Composition: C 51.84%, H 6.09%, Cl 15.30%, N 6.05%, O 20.72%
Properties: Crystals from alcohol and ether, mp 142-143°.
Melting point: mp 142-143°
Pyridoxal 5-Phosphate Pyridoxamine Dihydrochloride Pyridoxine Hydrochloride Pyrifenox Pyrimethamine

Skeletal formula of pyridoxal
Ball-and-stick model of pyridoxal
CAS number 66-72-8 YesY
65-22-5 (hydrochloride)
PubChem 1050
ChemSpider 1021 YesY
DrugBank DB00147
KEGG C00250 YesY
ChEBI CHEBI:17310 YesY
Jmol-3D images Image 1
Molecular formula C8H9NO3
Molar mass 167.16 g/mol
Melting point 165 °C (decomp.)
Related compounds
Related arylformaldehydes Damnacanthal


 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Pyridoxal is one of the three natural forms of vitamin B6, along with pyridoxamine and pyridoxine (also called "pyridoxol"). All of these forms are converted in the human body into a single biologically active form, pyridoxal 5-phosphate. All three forms of vitamin B6 are heterocyclic organic compounds. Green plants are a natural source of pyridoxal, and its deficiency in the human body can lead to serious complications such as epilepsy and seizures.

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.

There are generally three pyridoxal-phosphate (PLP) reactions: transamination, alpha elimination, and beta-elimination.

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[1]