Cyclooctatetraene
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| Names | |||
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Preferred IUPAC name
Cycloocta-1,3,5,7-tetraene
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| Other names
[8]Annulene
(1Z,3Z,5Z,7Z)-Cycloocta-1,3,5,7-tetraene 1,3,5,7-Cyclooctatetraene COT |
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| Identifiers | |||
629-20-9 
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| 3D model (Jmol) | Interactive image | ||
| ChemSpider |
553448
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| ECHA InfoCard | 100.010.074 | ||
| EC Number | 211-080-3 | ||
| RTECS number | CY1400000 | ||
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| Properties | |||
| C8H8 | |||
| Molar mass | 104.15 g/mol | ||
| Appearance | Clear yellow | ||
| Density | 0.9250 g/cm3, liquid | ||
| Melting point | −5 to −3 °C (23 to 27 °F; 268 to 270 K) | ||
| Boiling point | 142 to 143 °C (288 to 289 °F; 415 to 416 K) | ||
| immiscible | |||
| -53.9·10−6 cm3/mol | |||
| Hazards | |||
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EU classification (DSD)
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Flammable (F) Carc. Cat. 1 Muta. Cat. 2 Toxic (T) |
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| R-phrases |
R45, R46, R11, R36/38, R48/23/24/25, R65 |
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| S-phrases | S53, S45 | ||
| NFPA 704 | |||
| Flash point | −11 °C (12 °F; 262 K) | ||
| 561 °C (1,042 °F; 834 K) | |||
| Related compounds | |||
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Related hydrocarbons
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Cyclooctane Tetraphenylene |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is  ?) |
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| Infobox references | |||
1,3,5,7-Cyclooctatetraene (COT) is an unsaturated derivative of cyclooctane, with the formula C8H8. It is also known as [8]annulene. This polyunsaturated hydrocarbon is a colorless to light yellow flammable liquid at room temperature. Because of its stoichiometric relationship to benzene, COT has been the subject of much research and some controversy.
Unlike benzene, C6H6, cyclooctatetraene, C8H8, is not aromatic, although its dianion, C
8H2−
8 (cyclooctatetraenide), is. Its reactivity is characteristic of an ordinary polyene, i.e. it undergoes addition reactions. Benzene, by contrast, characteristically undergoes substitution reactions, not additions.
1,3,5,7-Cyclooctatetraene was initially synthesized by Richard Willstätter at Munich in 1905:
Willstätter noted that the compound did not exhibit the expected aromaticity. Between 1939 and 1943, chemists throughout the US unsuccessfully attempted to synthesize COT. They rationalized their lack of success with the conclusion that Willstätter had not actually synthesized the compound but instead its isomer, styrene. Willstätter responded to these reviews in his autobiography, where he noted that the American chemists were 'untroubled' by the reduction of his cyclooctatetraene to cyclooctane (a reaction impossible for styrene). During World War 2, Walter Reppe at BASF Ludwigshafen developed a simple, one-step synthesis of cyclooctatetraene from acetylene, providing material identical to that prepared by Willstätter. Any remaining doubts on the accuracy of Willstätter's original synthesis were resolved when Arthur C. Cope and co-workers at MIT reported, in 1947, a complete repetition of the Willstätter synthesis, step by step, using the originally reported techniques. They obtained the same cyclooctatetraene, and they subsequently reported modern spectral characterization of many of the intermediate products, again confirming the accuracy of Willstätter's original work.
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