Quadricyclane is a strained, multi-cyclic hydrocarbon with the formula CH₂(CH)₆. A white volatile colorless liquid, it is highly strained molecule (78.7 kcal/mol).

Isomerization In chemistry, isomerization or isomerisation is the process in which a molecule, polyatomic ion or molecular fragment is transformed into an isomer with a different chemical structure. Enolization is an example of isomerization, as is tautomeriz ...

of quadricyclane proceeds slowly at low temperatures.Petrov, V. A; Vasil’ev, N. V. “Synthetic Chemistry of Quadricyclane.” ''Current Organic Synthesis'' 3 (2006): 215–259 Because of quadricyclane’s strained structure and thermal stability, it has been studied extensively.

Preparation

Quadricyclane is produced by the irradiation of norbornadiene (bicyclo .2.1epta-2,5-diene) in the presence of

Michler's ketone Michler's ketone is an organic compound with the formula of CH3)2NC6H4sub>2CO. This electron-rich derivative of benzophenone is an intermediate in the production of dyes and pigments, for example Methyl violet. It is also used as a photosensitize ...

or ethyl Michler's ketone. Other sensitizers, such as

acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscibl ...

benzophenone Benzophenone is the organic compound with the formula (C6H5)2CO, generally abbreviated Ph2CO. It is a white solid that is soluble in organic solvents. Benzophenone is a widely used building block in organic chemistry, being the parent diarylket ...

acetophenone Acetophenone is the organic compound with the chemical formula, formula C6H5C(O)CH3. It is the simplest aromatic ketone. This colorless, viscous liquid is a precursor to useful resins and fragrances. Production Acetophenone is formed as a byprodu ...

, etc., may be used but with a lesser yield. The yield is higher for freshly distilled norbornadiene, but commercial reagents will suffice. : Synthesis of quadricyclane from norbornadiene

Synthesis of quadricyclane from norbornadiene

Proposed applications to solar energy

The conversion of

norbornadiene Norbornadiene is an organic compound and a bicyclic hydrocarbon. Norbornadiene is of interest as a metal-binding ligand, whose complexes are useful for homogeneous catalysis. It has been intensively studied owing to its high reactivity and distin ...

into quadricyclane is achievd with ~300nm

UV radiation Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiatio ...

. . When converted back to norbornadiene,

ring strain In organic chemistry, ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles are ...

energy is liberated in the form of heat (''ΔH'' = −89 kJ/mol). This reaction has been proposed to store

solar energy Solar energy is radiant light and heat from the Sun that is harnessed using a range of technologies such as solar power to generate electricity, solar thermal energy (including solar water heating), and solar architecture. It is an essen ...

. 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 Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is re ...

at relatively low temperatures (less than 400 °C). This property limits its applications, as propulsion systems may operate at temperatures exceeding 500 °C.

Reactions

Quadricyclane readily reacts with

acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main componen ...

to give a mixture of nortricyclyl acetate and exo-norbornyl acetate. Quadricyclane also reacts with many dienophiles to form 1:1 adducts.

Notes

{{Authority control Hydrocarbons Cyclopropanes Tetracyclic compounds