Quadricyclane is a strained, multi-cyclic hydrocarbon with the formula CH₂(CH)₆. A 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 tautomer ...

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 Irradiation is the process by which an object is exposed to radiation. An irradiator is a device used to expose an object to radiation, most often gamma radiation, for a variety of purposes. Irradiators may be used for sterilizing medical and p ...

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 ...

(bicyclo .2.1epta-2,5-diene) in the presence of Michler's ketone or ethyl Michler's ketone. Other sensitizers, such as

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

benzophenone Benzophenone is a naturally occurring organic compound with the formula (C6H5)2CO, generally abbreviated Ph2CO. Benzophenone has been found in some fungi, fruits and plants, including grapes. It is a white solid with a low melting point and ros ...

acetophenone Acetophenone is the organic compound with the 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 byproduct of the cumene ...

, 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

into quadricyclane is achieved with ~300 nm

UV radiation Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of t ...

. 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 ar ...

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

solar energy Solar energy is the radiant energy from the Sun's sunlight, light and heat, which can be harnessed using a range of technologies such as solar electricity, solar thermal energy (including solar water heating) and solar architecture. It is a ...

. 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 of a substance caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic ...

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 compone ...

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