Chemistry:Ammonium cyanate
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| Properties | |
| [NH 4][OCN] | |
| Molar mass | 60.056 g·mol−1 |
| Appearance | Colorless crystals |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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Ammonium cyanate is an inorganic compound with the formula [NH
4]+
[OCN]−
. It is a colorless, solid salt.
Structure and reactions
The structure of this salt was verified by X-ray crystallography. The respective C–O and C–N distances are 1.174(8) and 1.192(7) Å, consistent with the O=C=N−
description. Ammonium cation [NH
4]+
forms hydrogen bonds with cyanate anion O=C=N−
, but to N, not to O.[1]
The compound is notable as the precursor in the Wöhler synthesis of urea, an organic compound, from inorganic reactants.[2]
- NH+
4 + OCN−
→ (NH
2)
2CO[3]
This is generally credited as the first total synthesis of an organic compound. Wöhler's work with ammonium cyanate is sometimes credited for ending support for vitalism in the sciences, but this account has been criticised by both historians and chemists as reductive.[4][5]
Preparation
Ammonium cyanate can be produced with solutions of potassium cyanate and ammonium chloride which are mixed, heated and cooled.[6]
Alternatively the reaction can be carried out with lead cyanate and ammonia.[7]
- Pb(OCN)
2 + 2 NH
3 + 2 H
2O → Pb(OH)
2 + 2NH
4(OCN)
Molten urea decomposes into ammonium cyanate at about 152 °C (306 °F):[8]
- CO(NH
2)
2 → [NH
4]+
[OCN]−
References
- ↑ MacLean, Elizabeth J.; Harris, Kenneth D. M.; Kariuki, Benson M.; Kitchin, Simon J.; Tykwinski, Rik R.; Swainson, Ian P.; Dunitz; Jack D. (2003). "Ammonium cyanate shows N-H···N hydrogen bonding, not N-H···O". Journal of the American Chemical Society 125 (47): 14449–14451. doi:10.1021/ja021156x. PMID 14624593.
- ↑ Friedrich Wöhler (1828). "Ueber künstliche Bildung des Harnstoffs". Annalen der Physik und Chemie 88 (2): 253–256. doi:10.1002/andp.18280880206. Bibcode: 1828AnP....88..253W. https://www.biodiversitylibrary.org/itempdf/127264.
- ↑ Shorter, J. (1978). "The conversion of ammonium cyanate into urea. A saga on Reaction mechanisms". Chemical Society Reviews 7: 1–14. doi:10.1039/CS9780700001.
- ↑ Ramberg, Peter J. (2000). "The Death of Vitalism and the Birth of Organic Chemistry: Wohler's Urea Synthesis and the Disciplinary Identity of Organic Chemistry". Ambix 47 (3): 170–195. doi:10.1179/amb.2000.47.3.170. PMID 11640223.
- ↑ Brooke, John H. (1968). "Wöhler's Urea, and its Vital Force ?—A Verdict from the Chemists". Ambix 15 (2): 84–114. doi:10.1179/amb.1968.15.2.84.
- ↑ Tóth, Zoltán (1996). "A demonstration of Wöhler's experiment: Preparation of urea from ammonium chloride and potassium cyanate". Journal of Chemical Education 73 (6): 539. doi:10.1021/ed073p539.2. Bibcode: 1996JChEd..73..539T.
- ↑ Batchelor, James D.; Carpenter, Everett E.; Holder, Grant N.; Eagle, Cassandra T.; Fielder, Jon; Cummings, Jared (1998). "Recreation of Wöhler's Synthesis of Urea: An Undergraduate Organic Laboratory Exercise". The Chemical Educator 3 (6): 1–7. doi:10.1007/s00897980271a.
- ↑ Schaber, Peter M.; Colson, James; Higgins, Steven; Thielen, Daniel; Anspach, Bill; Brauer, Jonathan (2004). "Thermal decomposition (pyrolysis) of urea in an open reaction vessel". Thermochimica Acta 424 (1–2): 131–142. doi:10.1016/j.tca.2004.05.018. ISSN 0040-6031. Bibcode: 2004TcAc..424..131S.
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