2-Pyridinecarboxaldehyde

Synthesis

DMF (5 mL), mesitylene (0.25 mL, 1.8 x 10⁻³ mol), and Et₃SiH (1.166 mL, 7.2 x 10⁻³ mol) were added to 4-bromotoluene (0.616 g, 3.6 × 10⁻³ mol), [PdCl₂(dppp)] (0.053 g, 9 x 10⁻⁵ mol), and Na₂CO₃ (0.381 g, 3.6 × 10⁻³ mol) as references. Once sealed in the reactor, the system was purged several times with CO. The temperature was raised to 90 °C, and 3 bar of CO was added to the reactor. The reaction was stirred under these conditions for 18 hours, and then the reactor was allowed to cool. The reactants were filtered, and the filtrate was analyzed by GC-MS to determine the conversion and yield of the aldehyde. The final structure was confirmed to yield the title compound, pyridine-2-carboxaldehyde.

Figure: Synthetic Route of 2-Pyridinecarboxaldehyde

Chemical Properties

Yellow liquid

Uses

2-Pyridinecarboxaldehyde has been used:

• To synthesize chitosan based bifunctionalized adsorbent.
• In the aldol addition reaction with pyruvate in the presence of 2-keto-3-deoxy-6-phosphogluconate aldolase (KDPG) catalyst to form (S)-4-hydroxy-2-keto-4-(2′-pyridyl)butyrate.
• In the condensation reaction with (S)-()-α-methylbenzylamine and (R)-(+)-α-methylbenzylamine to synthesize two chiral (S)-()- and (R)-(+)Schiff base compounds.

It can also be combined with thiosemicarbazide to form 2-pyridinecarboxaldehyde thiosemicarbazone ligand (L) which can further complex with Ni(II) and Cu(II) salts (MX) to form [M(L)₂X₂] complexes.

Definition

ChEBI: 2-Pyridinecarboxaldehyde is a pyridinecarbaldehyde that is pyridine in which the hydrogen at position 2 is replaced by a formyl group.

Synthesis Reference(s)

Synthetic Communications, 23, p. 1775, 1993 DOI: 10.1080/00397919308011276

Purification Methods

Purification is achieved by bubbling sulfur dioxide into a solution of 50g of the aldehyde in 250mL of boiled water, under nitrogen, at 0o, until precipitation is complete. The bisulfite addition compound is filtered off rapidly and, after washing with a little water, is refluxed in 17% HCl (200mL) under nitrogen until a clear solution is obtained. Neutralisation with NaHCO3 and extraction with ether separated the aldehyde which is recovered by drying the extract, then distilling twice, under nitrogen. [Kyte et al. J Chem Soc 4454 1960, Beilstein 21 I 287, 21 III/IV 3495, 21/7 V 293.]