Pyridine-N-oxide

Pyridine-N-oxide
Skeletal formula
Ball-and-stick model
Names
IUPAC name
Pyridine-N-oxide
Other names
pyridine-1-oxide
Identifiers
694-59-7 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:29136 YesY
ChemSpider 12229 YesY
ECHA InfoCard 100.010.705
PubChem 12753
Properties
C5H5NO
Molar mass 95.101
Appearance colourless solid
Melting point 65 to 66 °C (149 to 151 °F; 338 to 339 K)
Boiling point 270 °C (518 °F; 543 K)
high
Acidity (pKa) 0.8 (of conjugate acid)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Pyridine-N-oxide is the heterocyclic compound with the formula C5H5NO. This colourless, hygroscopic solid is the product of the oxidation of pyridine. It was originally prepared using peracids as the oxidising agent.[1] The molecule is planar. The compound is used infrequently as an oxidizing reagent in organic synthesis.[2] It also serves as a ligand in coordination chemistry.

Synthesis and reactions

The oxidation of pyridine is effected with peracetic acid, a reaction that affords the protonated derivative. Subsequent treatment with base liberates the neutral oxide.[3]

Pyridine N-oxide is about 105 less basic than pyridine. It does however form an isolable hydrochloride [C5H5NOH]Cl. Chlorination of the N-oxide with phosphorus oxychloride gives 4- and 2-chloropyridines.[4]

Safety

The compound is a skin irritant.

References

  1. ↑ J. Meisenheimer (1926). "Über Pyridin-, Chinolin- und Isochinolin-N-oxyd". Berichte der deutschen chemischen Gesellschaft. 59 (8): 1848–1853. doi:10.1002/cber.19260590828.
  2. ↑ S. Nicholas Kilényi "Pyridine N-Oxide" in Encyclopedia of Reagents for Organic Synthesis, 2001 John Wiley & Sons, New York. doi:10.1002/047084289X.rp283 Article Online Posting Date: April 15, 2001
  3. ↑ H. S. Mosher, L. Turner, and A. Carlsmith (1963). "Pyridine-N-oxide". Org. Synth.; Coll. Vol., 4, p. 828
  4. ↑ E. F. V. Scriven "Pyridines and their Benzo Derivatives: (ii) Reactivity at Ring Atoms" in Comprehensive Heterocyclic Chemistry 1984, Volume 2, Pages 165–314. doi:10.1016/B978-008096519-2.00027-8
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