Carbon diselenide

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Carbon diselenide
Carbon diselenide.png
Carbon-diselenide-3D-balls.png
Carbon-diselenide-3D-vdW.png
Identifiers
CAS number 506-80-9 YesY
PubChem 68174
ChemSpider 61481 N
Jmol-3D images Image 1
Properties
Molecular formula 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)
Solubility in water 0.054 g/100 mL
Solubility soluble in CS2, toluene
Dipole moment 0 D
Thermochemistry
Specific
heat capacity
C
5032 J/mol K
Std molar
entropy
So298
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 are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
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[edit]

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[edit]

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 synthetized 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[edit]

  1. ^ a b 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 .