Pyridine-4-carbaldehyde is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula C₅H₄NCHO. It is one of three isomeric pyridinaldehydes. The other isomers are pyridine-2-carboxaldehyde and pyridine-3-carboxaldehyde. Pyridine-4-carboxaldehyde is a colorless liquid, although aged samples can appear yellow or even brown. It undergoes many reactions expected for aromatic

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

s such as reductive amination and

Schiff base In organic chemistry, a Schiff base (named after Hugo Schiff) is a compound with the general structure ( = alkyl or aryl, but not hydrogen). They can be considered a sub-class of imines, being either secondary ketimines or secondary aldim ...

formation. It condenses with pyrrole to give tetrapyridyl

porphyrin Porphyrins ( ) are heterocyclic, macrocyclic, organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (). In vertebrates, an essential member of the porphyrin group is heme, w ...

. The pKa has been experimentally determined by NMR spectroscopy to be 4.72.

References

{{reflist Aromatic aldehydes 4-Pyridyl compounds