Quadricyclane
Encyclopedia
Quadricyclane is a strained, multi-cyclic hydrocarbon with potential uses as an additive for rocket propellant
s as well in solar energy conversion. These uses are limited, however, by the molecule's decomposition at relatively low temperatures (less than 400 °C).
molecule (78.7 kcal/mol). Isomerization of quadricyclane proceeds slowly at low temperatures without the use of a catalyst. Because of quadricyclane’s strained structure and thermal stability, it has been studied extensively.
The conversion from norbornadiene
with a catalyst is done by UV radiation with wavelength of about 300 nm. 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. 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.
or ethyl Michler's ketone. 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.
to give a mixture of nortricyclyl acetate and exo-norbornyl acetate. Quadricyclane also reacts with many dienophiles to form 1:1 adducts.
Rocket propellant
Rocket propellant is mass that is stored in some form of propellant tank, prior to being used as the propulsive mass that is ejected from a rocket engine in the form of a fluid jet to produce thrust. A fuel propellant is often burned with an oxidizer propellant to produce large volumes of very hot...
s 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 strainedStrain energy
In a molecule, strain energy is released when the constituent atoms are allowed to rearrange themselves in a chemical reaction or a change of chemical conformation in a way that:* angle strain,* torsional strain,* ring strain and/or steric strain,...
molecule (78.7 kcal/mol). Isomerization of quadricyclane proceeds slowly at low temperatures without the use of a catalyst. Because of quadricyclane’s strained structure and thermal stability, it has been studied extensively.
The conversion from norbornadiene
Norbornadiene
Norbornadiene is an organic compound. This bicyclic hydrocarbon is the most stable diolefin derived from the norbornane and norbornene. Norbornadiene is primarily of interest as a ligand in homogeneous catalysis, but it has been heavily studied due to its high reactivity and distinctive...
with a catalyst is done by UV radiation with wavelength of about 300 nm. When converted back to norbornadiene via irradiation
Irradiation
Irradiation is the process by which an object is exposed to radiation. The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve a specific purpose, rather than radiation exposure to...
, 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. 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
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....
at relatively low temperatures (less than 400 °C). This property limits its applications, as propulsion systems may operate at temperatures exceeding 500 °C.
Preparation
Quadricyclane is produced by the irradiation of norbornadiene (bicyclo[2.2.1]hepta-2,5-diene) in the presence of Michler's ketoneMichler's ketone
Michler’s ketone is an organic compound with the formula of [2NC6H4]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 sensitizer...
or ethyl Michler's ketone. Other sensitizers, such as acetone
Acetone
Acetone is the organic compound with the formula 2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones.Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory...
, benzophenone
Benzophenone
Benzophenone is the organic compound with the formula 2CO, generally abbreviated Ph2CO. Benzophenone is a widely used building block in organic chemistry, being the parent diarylketone.-Uses:...
, acetophenone
Acetophenone
Acetophenone is the organic compound with the formula C6H5CCH3. It is the simplest aromatic ketone. This colourless, viscous liquid is a precursor to useful resins and fragrances.-Production:Acetophenone can be obtained by a variety of methods...
, etc., may be used but with a lesser yield. The yield is higher for freshly distilled norbornadiene, but commercial reagents will suffice.
Reactions
Quadricyclane readily reacts with acetic acidAcetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
to give a mixture of nortricyclyl acetate and exo-norbornyl acetate. Quadricyclane also reacts with many dienophiles to form 1:1 adducts.