Quadricyclane
| Quadricyclane | |
|---|---|
| File:Quadricyclane.png | |
| Other names quadricyclo[2.2.1.02,6.03.5]heptane, tetracyclo[2.2.1.02,6.03,5]heptane | |
| Identifiers | |
| CAS number | 278-06-8 7px |
| Jmol-3D images | Image 1 |
| |
| Molecular formula | C7H8 |
| Molar mass | 92.14 g/mol |
| Density | 0.982 g/cm3 |
| Melting point |
−44 °C, 229 K, -47 °F |
| Boiling point |
108 °C, 381 K, 226 °F (at 987 hPa) |
| Solubility in water | Insoluble |
| Hazards | |
| R-phrases | R11 R23 |
| S-phrases | S16 S29 S33 S45 |
| 14px (verify) (what is: 10px/10px?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
| Infobox references | |
Quadricyclane is a strained, multi-cyclic hydrocarbon with potential uses as an additive for rocket propellants as well in solar energy conversion. These uses are limited, however, by the molecule's decomposition at relatively low temperatures (less than 400 °C).
Structure and properties
Quadricyclane is a highly strained molecule (78.7 kcal/mol). Isomerization of quadricyclane proceeds slowly at low temperatures without the use of a catalyst.[1] Because of quadricyclane’s strained structure and thermal stability, it has been studied extensively.
In the presence of a catalyst norbornadiene is converted into quadricyclane via ~300nm UV radiation .[2] When converted back to norbornadiene via irradiation, quadryicyclane’s ring strain energy is liberated in the form of heat (ΔH = −89 kJ/mol). This reaction has been proposed to store solar energy.[3][4] However, the absorption edge of light does not extend past 300 nm whereas most solar radiation has wavelengths longer than 400 nm. Quadricyclane’s relative stability and high energy content have also given rise to its use as a propellant additive or fuel. However, quadricyclane undergoes thermal decomposition at relatively low temperatures (less than 400 °C). This property limits its applications, as propulsion systems may operate at temperatures exceeding 500 °C.[5]
Preparation
Quadricyclane is produced by the irradiation of norbornadiene (bicyclo[2.2.1]hepta-2,5-diene) in the presence of Michler's ketone or ethyl Michler's ketone.[6] Other sensitizers, such as acetone, benzophenone, acetophenone, etc., may be used but with a lesser yield. The yield is higher for freshly distilled norbornadiene, but commercial reagents will suffice.[7]
Reactions
Quadricyclane readily reacts with acetic acid to give a mixture of nortricyclyl acetate and exo-norbornyl acetate.[1] Quadricyclane also reacts with many dienophiles to form 1:1 adducts.[7]
Notes
- ↑ 1.0 1.1 Petrov, V. A; Vasil’ev, N. V. “Synthetic Chemistry of Quadricyclane.” Current Organic Synthesis 3 (2006): 215–259
- ↑ Script error
- ↑ Dubonosov, A. D; Bren, V. A; Chernoivanov, V. A. “Norbornadiene – quadricyclane as an abiotic system for the storage of solar energy.” Russian Chemical Reviews 71 (2002): 917–927
- ↑ Script error
- ↑ Script error
- ↑ Cahill, P; Steppel, R. Process of quadricyclane production. U.S. Patent 10,661,194 filed September 12, 2003, and issued March 18, 2004
- ↑ 7.0 7.1 Smith, Claiborune D. (1988), "Quadricyclane", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6p0962; Coll. Vol. 6: 962
