Difference between revisions of "Cyanogen"
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Acidic aqueous solutions of cyanide yield cyanogen besides variable amounts of HCN gas when treated with oxidizing agents (H<sub>2</sub>O<sub>2</sub>, Na<sub>2</sub>S<sub>2</sub>O<sub>8</sub>, SnO<sub>2</sub>, PbO<sub>2</sub>, K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub>, MnO<sub>2</sub>, KMnO<sub>4</sub>).<ref name="gmelinc" /><ref>R. Ricaa, F. Pirrone, ''Ann. Chim. Appl.'' '''18''', 550-555 (1928)</ref> | Acidic aqueous solutions of cyanide yield cyanogen besides variable amounts of HCN gas when treated with oxidizing agents (H<sub>2</sub>O<sub>2</sub>, Na<sub>2</sub>S<sub>2</sub>O<sub>8</sub>, SnO<sub>2</sub>, PbO<sub>2</sub>, K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub>, MnO<sub>2</sub>, KMnO<sub>4</sub>).<ref name="gmelinc" /><ref>R. Ricaa, F. Pirrone, ''Ann. Chim. Appl.'' '''18''', 550-555 (1928)</ref> | ||
| − | Aqueous solutions of cyanide may be oxidized by copper(II) to form cyanogen. The gas is >89% pure and the yield is 41%:<ref name="gmelinc" /><ref>G. J. Janz, ''Inorganic Syntheses'' '''5''', 43-48 (1957)[https://doi.org/10.1002/9780470132364.ch12 https://doi.org/10.1002/9780470132364.ch12]</ref> | + | Aqueous solutions of cyanide may be oxidized by copper(II) to form cyanogen. The gas is >89% pure and the yield is 41%:<ref name="gmelinc" /><ref>G. J. Janz, ''Inorganic Syntheses'' '''5''', 43-48 (1957). [https://doi.org/10.1002/9780470132364.ch12 https://doi.org/10.1002/9780470132364.ch12]</ref> |
: 4 KCN + 2 CuSO<sub>4</sub> → (CN)<sub>2</sub> + 2 CuCN + 2 K<sub>2</sub>SO<sub>4</sub> | : 4 KCN + 2 CuSO<sub>4</sub> → (CN)<sub>2</sub> + 2 CuCN + 2 K<sub>2</sub>SO<sub>4</sub> | ||
Latest revision as of 15:17, 30 July 2023
| Names | |
|---|---|
| IUPAC name
Oxalonitrile
| |
| Other names
Bis(nitridocarbon)(C—C)
Carbon nitride Cyanogen Dicyan Dicyanogen Ethanedinitrile Nitriloacetonitrile Oxalic acid dinitrile Oxalyl cyanide | |
| Properties | |
| C2N2 (CN)2 | |
| Molar mass | 52.036 g/mol |
| Appearance | Colorless gas |
| Odor | Almond-like |
| Density | 0.002321 g/cm3 (0 °C) |
| Melting point | −28 °C (−18 °F; 245 K) |
| Boiling point | −21.1 °C (−6.0 °F; 252.1 K) |
| 45 g/100 ml (at 20 °C) | |
| Solubility | Soluble in diethyl ether, ethanol |
| Vapor pressure | 5.1 atm (21 °C) |
| Thermochemistry | |
| Std molar
entropy (S |
241.57 J·K−1·mol−1 |
| Std enthalpy of
formation (ΔfH |
309.07 kJ/mol |
| Hazards | |
| Safety data sheet | Matheson |
| Related compounds | |
| Related compounds
|
Hydrogen cyanide |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Cyanogen, also known as dicyanogen or oxalonitrile is a colorless, toxic gas with a pungent almond-like odor. It is a pseudohalogen, with the chemical formula (CN)2.
Contents
Properties
Chemical
Hydrolysis of cyanogen gives oxamide.
Physical
Cyanogen is a colorless gas, with an almond-like odor, highly poisonous. Its odor is also described as just pungent.[1] It is soluble in water, but more soluble in some organic solvents, like alcohols and ethers.
Availability
Cyanogen is sold by industrial gas companies, but due to its extreme dangers, it is not sold to the general public.
Preparation
Cyanogen can be produced by the pyrolysis of oxamide at 350 °C, which in turn can be obtained from the thermal decomposition of ammonium oxalate. Heating oxamide with P2O5 yields cyanogen in 86% yield.[2] Heating ammonium oxalate in glycerin also produces cyanogen, as well as ammonium cyanide, ammonium formiate and ammonium carbonate.[3]
Acidic aqueous solutions of cyanide yield cyanogen besides variable amounts of HCN gas when treated with oxidizing agents (H2O2, Na2S2O8, SnO2, PbO2, K2Cr2O7, MnO2, KMnO4).[1][4]
Aqueous solutions of cyanide may be oxidized by copper(II) to form cyanogen. The gas is >89% pure and the yield is 41%:[1][5]
- 4 KCN + 2 CuSO4 → (CN)2 + 2 CuCN + 2 K2SO4
Thermal decomposition of Hg(CN)2 in vacuum at 400 °C yields cyanogen.[6] Mixing with an equal amount of glass powder makes the reaction faster and cleaner.[1]
- Hg(CN)2 → Hg + (CN)2
Pyrolysis of AgCN (dried at 130 °C for 12 h) in vacuum at 380 °C will also yield cyanogen.[7]
Projects
Due to the extreme toxicity of cyanogen, it's best to work with it only if you have experience working with toxic gaseous compounds. Work in well ventilated chambers or under a fumehood and proper protection equipment, such as cyanide-rated filter mask and gloves must be worn at all times.
- Make oxamide
- Make paracyanogen
- Make the second hottest flame known to man
Handling
Safety
Dicyanogen is metabolized by the organism to cyanide, which is very toxic. Lethal dose through inhalation typically ranges from 100 to 150 mg. Inhalation of 900 ppm over a period of 10 minutes is considered lethal.
Storage
Cyanogen should only be stored in metal gas cylinders, away from light and heat, and preferably in an isolated place. Periodically inspect the tube for any signs of corrosion.
Disposal
Can be destroyed by bubbling it in an oxidizing solution. Burning it is not recommended as it may release hydrogen cyanide fumes.
References
- ↑ 1.0 1.1 1.2 1.3 Gmelins Handbuch der anorganischen Chemie, Kohlenstoff Teil D1, Verlag Chemie GmbH, Weinheim/Bergstraße, 8th edition 1971, p. 44, 48
- ↑ E. Ott, Ber. dtsch. Chem. Ges. A/B 52, 657 (1919). https://doi.org/10.1002/cber.19190520406
- ↑ L. Storch, Ber. Dtsch. Chem. Ges. 19, 2459 (1886). https://doi.org/10.1002/cber.188601902182
- ↑ R. Ricaa, F. Pirrone, Ann. Chim. Appl. 18, 550-555 (1928)
- ↑ G. J. Janz, Inorganic Syntheses 5, 43-48 (1957). https://doi.org/10.1002/9780470132364.ch12
- ↑ J. H. Perry, D. C. Bardwell, J. Am. Chem. Soc. 47, 11, 2629–2632 (1925), https://doi.org/10.1021/ja01688a002
- ↑ R. A. Ruehrwein, W. F. Giauque, J. Am. Chem. Soc. 61, 10, 2940–2944 (1939), https://doi.org/10.1021/ja01265a104
