Carbon diselenide

Carbon diselenide
Names
Other names
Carbon selenide, diselenoxomethane, methanediselone
Identifiers
506-80-9 Yes
ChemSpider 61481 
Jmol-3D images Image
PubChem 68174
Properties
CSe2
Molar mass 169.93 g/mol
Appearance yellow liquid
Density 2.6824 g/cm 3
Melting point −43.7 °C (−46.7 °F; 229.5 K)
Boiling point 125.5 °C (257.9 °F; 398.6 K)
0.054 g/100 mL
Solubility soluble in CS2, toluene
Dipole moment 0 D
Thermochemistry
Specific
heat capacity (C)
 5032 J/mol K
263.2 J/mol K
Std enthalpy of
formation (ΔfHo298)
 219.2 kJ/mol
Hazards
Flash point 30 °C (86 °F; 303 K)
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Carbon diselenide is an inorganic compound with the chemical formula CSe2. It is a yellow-orange oily liquid with pungent odor. It is an analogue of carbon disulfide (CS2). This light-sensitive compound is insoluble in water and soluble in organic solvents.

Synthesis, structure and reactions

Carbon diselenide is a linear molecule with D∞h symmetry. It is produced by reacting selenium powder with dichloromethane vapor near 550 °C.[1]

2 Se + CH2Cl2 → CSe2 + 2 HCl

It was first reported by Grimm and Metzger, who prepared it by treating hydrogen selenide with carbon tetrachloride in a hot tube.[2]

Like carbon disulfide, carbon diselenide polymerizes under high pressure. The structure of the polymer is thought to be a head-to-head structure with a backbone in the form of –[Se–C(=Se)–C(=Se)–Se]–.[3] The polymer is a semiconductor with a room-temperature conductivity of 50 S/cm.

In addition, carbon diselenide is a precursor to tetraselenafulvalenes,[4] the selenium analogue of tetrathiafulvalene, which can be further used to synthesize organic conductors and organic superconductors.

Carbon diselenide reacts with secondary amines to give dialkydiselenocarbamates:[1]

2 Et2NH + CSe2 → (Et2NH2+)(Et2NCSe2−)

Safety

Carbon diselenide has high vapor pressure. It is toxic and presents an inhalation hazard. It may be dangerous due to its easy membrane transport. It decomposes slowly in storage (about 1% per month at –30 °C). When obtained commercially, its cost is high.[5]

Mixed with air, CSe2 releases an extremely offensive odor.[6] Its smell forced an evacuation of a nearby village when it was first synthesized in 1936. The stench can be neutralized by oxidizing with bleach.[7] Because of the odor, synthetic pathways have been developed to avoid its use.[8]

References

  1. ↑ 1.0 1.1 Pan, W.-H.; Fackler, J. P. Jr.; Anderson, D. M.; Henderson, S. G. D.; Stephenson, T. A. (1982). "2. Diselenocarbamates from Carbon Diselenide". In Fackler, J. P. Jr. Inorganic Syntheses 21. pp. 6–11. doi:10.1002/9780470132524.ch2. ISBN 978-0-470-13252-4.
  2. ↑ Grimm, H. G.; Metzger, H. (1936). "Über Darstellung und Eigenschaften des Selenkohlenstoffs". Berichte der deutschen chemischen Gesellschaft (A and B Series) 69 (6): 1356–1364. doi:10.1002/cber.19360690626.
  3. ↑ Carraher, C. E. Jr.; Pittman, C. U. Jr. (2005). "Poly(Carbon Disulfide), Poly(Carbon Diselenide), and Polythiocyanogen". Inorganic Polymers 21. doi:10.1002/14356007.a14_241. ISBN 3-527-30673-0.
  4. ↑ Engler, E. M.; Patel, V. V. (1974). "Structure control in organic metals. Synthesis of tetraselenofulvalene and its charge transfer salt with tetracyano-p-quinodimethane". Journal of the American Chemical Society 96 (23): 7376–7378. doi:10.1021/ja00810a042.
  5. ↑ "Carbon Diselenide CSe2". Cse2.com. Retrieved 2012-04-04.
  6. ↑ Wolfgang H. H. Gunther. Organic Selenium Compounds: Their Chemistry and Biology. carbon diselenide has by far the worst odor this author has experienced in his lifetime of working with selenium compounds
  7. ↑ Derek Lowe. "Things I Won't Work With: Carbon Diselenide". In the Pipeline. Corante. Retrieved 2012-04-04.
  8. ↑ US patent 4462938, Wudl, F., "Process for producing chalcogen containing compounds", issued 1984-07-31, assigned to AT&T Bell Laboratories.