Carbon suboxide
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| General | ||||||||||
| Surname | Carbon suboxide | |||||||||
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| Molecular formula | C 3 O 2 | |||||||||
| Brief description |
colorless gas |
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| properties | ||||||||||
| Molar mass | 68.03 g mol −1 | |||||||||
| Physical state |
gaseous |
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| density |
3.0 kg m −3 |
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| Melting point |
−107 ° C |
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| boiling point |
6.8 ° C |
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| Refractive index |
1.4538 (0 ° C) |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C | ||||||||||
Carbon suboxide , also known as carbon suboxide or malonic anhydride , is, in addition to carbon monoxide , carbon dioxide and mellitic anhydride , another carbon oxide, i.e. a compound that is made up exclusively of carbon and oxygen. It is gaseous and stable at room temperature. The poisonous and foul-smelling substance belongs to the group of ketenes , but in contrast to most of the other representatives of this group, it has two carbonyl groups (C = O).
history
Benjamin Collins Brodie Junior discovered the compound in 1873 when an electric current was applied to carbon monoxide. The name carbon suboxide goes back to Marcelin Berthelot .
presentation
In addition to the presentation by dehydration of malonic acid with phosphorus pentoxide :
carbon suboxide can be obtained by thermal decomposition from diacetyltartaric anhydride, pyrolysis of oxaloacetic acid diethyl ether or dehalogenation of dibromomalonyl chloride.
properties
Physical Properties
The connection is built linear. The bond lengths are between the values expected for double and triple bonds : 128 pm for the two C − C bonds and 116 pm for the two C − O bonds.
Chemical properties
Carefully cleaned, carbon suboxide is resistant. When introduced into water, it reacts to form malonic acid . In the gas phase it is stable to ozone and reacts moderately quickly with hydroxyl radicals (the lifespan in the atmosphere is about three days).
In the presence of proton-releasing substances, through radiolysis or photolysis, carbon suboxide polymerizes into macromolecules . The red to black solid polymerization product (called “red carbon” and “red carbon” in the literature) has a ribbon-like structure ( see web links ) and is made up of around 40 C 3 O 2 units with a polypyrone-like structure. Is also a copolymerization with polyethylene to cross-linked copolymers possible.
Carbon suboxide reacts with nucleophiles such as amines, alcohols, phenols or thiols to form malonic acid amides, esters or thioesters. With hydrazines , pyrazolidine derivatives can be produced via ring-closing reactions . Different heterocycles can be synthesized accordingly. For example, thioamides react to give thiazinone derivatives and enamines to give the corresponding pyridones. About a photochemical reaction can be produced from ethylene Allen produced.
Web links
Individual evidence
- ↑ a b c d e webelements.com (carbon suboxide) (engl.)
- ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-88.
- ↑ a b Data sheet carbon suboxide (PDF) from Merck , accessed on January 19, 2011. In the absence of better sources, the hazardous substance labeling of malonic acid is given here, modified accordingly for inhalation, which also apply to carbon suboxide, as this immediately turns into malonic acid on contact with water responds
- ^ BC Brodie: Note on the Synthesis of Marsh-Gas and Formic Acid, and on the Electric Decomposition of Carbonic Oxide , in: Proceedings of the Royal Society (London) , 1873 , 21 , pp. 245-247. - Justus Liebig's Annals of Chemistry and Pharmacy 169 , 270 (1873)
- ↑ a b c Thomas cap, Erich Ziegler: Carbon suboxide in preparative organic chemistry . In: Angewandte Chemie . tape 86 , no. 15 , 1974, p. 529-542 , doi : 10.1002 / anie.19740861502 .
- ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 901.
- ↑ Stephan Keßel et al .: Atmospheric Chemistry, Sources, and Sinks of Carbon Suboxide, C 3 O 2 . Atmos. Chem. Phys., 2017 ( Reviewed ), doi: 10.5194 / acp-2017-49 (free full text).