Cyanic Acid

Title: Cyanic Acid
CAS Registry Number: 420-05-3
Additional Names: Hydrogen cyanate
Molecular Formula: CHNO
Molecular Weight: 43.02
Percent Composition: C 27.92%, H 2.34%, N 32.56%, O 37.19%
Literature References: Best prepd in the laboratory by dry distillation of cyanuric acid: Linhard, Z. Anorg. Allg. Chem. 236, 200 (1938). See also Isocyanic Acid.
Properties: Liquid. Acrid odor, strong lacrimator and vesicant. d420 1.140; d4-20 1.156. mp -86°. bp760 23.5°. Heat of formation -36.5 kcal/mol. Dipole moment 1.592. pK (20°) 3.66. Rapid heating of the liq may result in an explosion. Polymerizes on standing forming cyamelide and cyanuric acid. Sol in water with decompn to carbon dioxide and ammonia. Dil solns in ice water may be kept for several hours. Dil solns in ether, benzene, toluene can be kept for several weeks.
Melting point: mp -86°
Boiling point: bp760 23.5°
pKa: pK (20°) 3.66
Density: d420 1.140; d4-20 1.156
CAUTION: Highly irritating to eyes, skin, and mucous membranes. See Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams & Wilkins, Baltimore, 5th ed., 1984) Section II, p 110.
Use: In formation of some cyanates.
Cyanidin Chloride Cyanoacetamide Cyanoacetic Acid Cyanofenphos Cyanogen

Isocyanic acid
Isocyanic acid 3D balls.png
CAS number 75-13-8 YesY
420-05-3 (cyanic acid)
PubChem 6347
ChemSpider 6107 YesY
ChEBI CHEBI:29202 YesY
Jmol-3D images Image 1
Molecular formula HNCO
Molar mass 43.03 g/mol
Appearance Colorless liquid or gas (b.p. near room temperature)
Density 1.14 g/cm3 (20 °C)
Melting point -86 °C [1]
Boiling point 23.5 °C
Solubility in water Dissolves
Solubility Soluble in benzene, toluene, ether
Main hazards Poisonous
 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

Isocyanic acid is an organic compound with the formula HNCO, discovered in 1830 by Liebig and Wöhler.[2] This colourless substance is volatile and poisonous, with a boiling point of 23.5 °C. Isocyanic acid is the simplest stable chemical compound that contains carbon, hydrogen, nitrogen, and oxygen, the four most commonly found elements in organic chemistry and biology.