6578. Nitric Oxide

Nomenclature

CAS number: 10102-43-9
Nitrogen oxide (NO); mononitrogen monoxide; nitrogen monoxide; endothium-derived relaxing factor; EDRF.
NO; mol wt 30.01.
N 46.67%, O 53.31%.

Description and references

Highly reactive, potentially toxic gas produced by the partial oxidation of atmospheric nitrogen. Major air pollutant along with its oxidative by-products (NOx) resulting from incomplete combustion of fossil fuels. Also found ubiquitously in animals; generated in vivo from arginine, q.v., by nitric oxide synthase (NOS). Increases guanylate cyclase activity to produce cyclic GMP, q.v. Involved in a wide range of physiological functions, including vasodilation, neurotransmission, cytotoxicity of macrophages, and inhibition of platelet aggregation. Laboratory prepn: Blanchard, Inorg. Synth. 2, 126 (1946); Schenk in Handbook of Preparative Inorganic Chemistry vol. 1, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) pp 485-487. General reviews: Beattie, “Nitric Oxide” in Mellor's Vol. VIII, supplement II, Nitrogen (part 2) 216-240 (1967); Jones in Comprehensive Inorganic Chemistry vol. 2, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 323-334. Role in cGMP production: W. P. Arnold et al., Proc. Natl. Acad. Sci. USA 74, 3203 (1977). Identification of endothelium dependent vasorelaxation: R. F. Furchgott, J. V. Zawadzki, Nature 288, 373 (1980). Identity of NO and EDRF: L. J. Ignarro et al., Proc. Natl. Acad. Sci. USA 84, 9265 (1987). Reviews of physiological role: S. Moncada et al., Pharmacol. Rev. 43, 109-142 (1991); A. R. Butler, D. L. H. Williams, Chem. Soc. Rev. 22, 233-242 (1993). Role in airway function: R. J. Martin et al., Semin. Perinatol. 26, 432 (2002). Clinical trial of inhaled NO in neonatal respiratory failure: G. M. Sokol, R. A. Ehrenkranz, ibid. 27, 311 (2003). Review of pharmacology and therapeutic potential of inhaled NO: F. Ichinose et al., Circulation 109, 3106-3111 (2004). Review of chemistry: D. L. H. Williams, Org. Biomol. Chem. 1, 441-449 (2003); of coordination chemistry in bio-inorganic systems: J. A. McCleverty, Chem. Rev. 104, 403-418 (2004).

Properties

Colorless gas. Burns only when heated with hydrogen. triple pt -163.6°. bp -151.8°. d-150.2 (liq) 1.27. Relative d (gas) 1.036 (air = 1). Absolute d (gas) 1.227 (air = 1). nD25 1.0002697. Trouton constant 27.1. Contains an odd number of electrons and is paramagnetic. Crit temp -92.9°. Crit press. 64.6 atm. Heat of formation (18°): -21.5 kcal/mole. Heat of vaporization (bp): 3.293 kcal/mole. Ionization potential: 9.26 eV. Electron affinity: 0.024 eV. Solubility in water (ml/100 ml; 1 atm): 7.38 (0°); 4.6 (20°); 2.37 (60°). Combines with oxygen to form NO2 and with chlorine and bromine to form the nitrosyl halides, such as NOCl, see N. V. Sidgwick, Chemical Elements and Their Compounds vol. I (Oxford, 1950) p 683.

Caution

Potential symptoms of overexposure are irritation of eyes, wet skin, nose and throat; drowsiness; unconsciousness; methemoglobinemia. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 224. On contact with air, nitric oxide is converted to the highly poisonous nitrogen dioxide, q.v. Respiratory protection and adequate ventilation should be used to avoid overexposure. See Patty's Industrial Hygiene and Toxicology vol. 2F, G. D Clayton, F. E. Clayton, Eds. (John Wiley & Sons, New York, 4th ed., 1994) pp 4566-4591.

Use

Manuf of nitric acid; in the bleaching of rayon; as stabilizer (to prevent free-radical decompn) for propylene, methyl ether, etc.

Therapeutic Category

Vasodilator (pulmonary); in treatment of neonatal cardiorespiratory failure.