Cubane

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Cubane

Cubane (C₈H₈) is a synthetic hydrocarbon

Hydrocarbon

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. With relation to chemical terminology, aromatic hydrocarbons or arenes, alkanes, alkenes and alkyne-based compounds composed entirely of carbon or hydrogen are referred to as "pure" hydrocarbons, whereas other hydrocarbons with bonded com...
molecule

Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
that consists of eight carbon

Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
atom

Atom

|-! bgcolor=gray | Properties|-||}The atom is a basic unit of matter consisting of a dense, central atomic nucleus surrounded by a electron cloud of electric charge electrons....
s arranged at the corners of a cube, with one hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
atom attached to each carbon atom. It is one of the Platonic hydrocarbons

Platonic hydrocarbons

Platonic hydrocarbons are the molecule representation of platonic solid geometries with vertices replaced by carbon atoms and with edges replaced by chemical bonds....
. Cubane is a solid crystal

Crystal

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions....
line substance. The cubane molecule was first synthesized in 1964 by Dr. Philip Eaton

Philip Eaton

Philip E. Eaton is a Professor Emeritus of Chemistry at the University of Chicago. He and his fellow researchers were the first to synthesize the "impossible" cubane molecule in 1964....
, a professor of chemistry at the University of Chicago

University of Chicago

The University of Chicago is a private university located principally in the Hyde Park, Chicago neighborhood of Chicago. Although an older university by the same name existed prior to its founding, the modern University of Chicago credits its founding to the oil magnate John D....
. Before its synthesis, researchers believed that cubic carbon-based molecules could only exist in theory.

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Encyclopedia

Cubane (C₈H₈) is a synthetic hydrocarbon

Hydrocarbon

Molecule

Carbon

Atom

Hydrogen

Platonic hydrocarbons

Platonic hydrocarbons are the molecule representation of platonic solid geometries with vertices replaced by carbon atoms and with edges replaced by chemical bonds....
. Cubane is a solid crystal

Crystal

Philip Eaton

University of Chicago

Strain (chemistry)

In chemistry a molecule experiences strain when in a chemical conformation there exist unfavorable bond angles or bond distances. Strain energy is released when the molecule can relax to a conformation with less strain or when the molecule interacts in a suitable chemical reaction....
and hence unstable. Surprisingly, once formed, cubane is actually quite kinetically stable due to a lack of readily available decomposition paths.

Cubane and its derivative compounds have many important properties. The 90-degree bonding angle of the carbon atoms in cubane means that the bonds are highly strained. Therefore, cubane compounds are highly reactive, which in principle may make them useful as high-density, high-energy fuel

Fuel

Fuel is any material that is burned or altered in order to obtain energy and to heat or to move an object. Fuel releases its energy either through a chemical reaction means, such as combustion, or nuclear means, such as nuclear fission or nuclear fusion....
s and explosives for example octanitrocubane

Octanitrocubane

Octanitrocubane is a powerful high explosive that, like Trinitrotoluene, is shock-insensitive . The octanitrocubane molecule has the same chemical structure as cubane except that each of the eight hydrogen atoms are replaced by a nitro compound ....
and heptanitrocubane

Heptanitrocubane

Heptanitrocubane is a new experimental Explosive based on the cubic eight-carbon cubane molecule and closely related to octanitrocubane. Seven of the eight hydrogen atoms at the corners of the cubane molecule are replaced by nitro groups, giving the final molecular formula ....
. Cubane also has the highest density of any hydrocarbon, further contributing to its ability to store large amounts of energy. Researchers are looking into using cubane and similarly synthesized cubic molecules in medicine

Medicine

Medicine is the art and science of healing. It encompasses a range of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
and nanotechnology

Nanotechnology

Nanotechnology, shortened to "Nanotech", is the study of the control of matter on an atomic and molecular scale. Generally nanotechnology deals with structures of the size 100 nanometers or smaller, and involves developing materials or devices within that size....
.

Synthesis

The original 1964 cubane organic synthesis

Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic_chemistry molecules can often contain a higher level of complexity compared to purely Inorganic_chemistry compounds, so the synthesis of organic compounds has developed into one of the most im...
is a classic and starts from 2-cyclopentenone (compound 1.1 in scheme 1):

Reaction with N-bromosuccinimide

N-Bromosuccinimide

N-Bromosuccinimide or NBS is a chemical reagent which is used in radical substitution and electrophilic addition chemical reaction in organic chemistry....
in carbon tetrachloride

Carbon tetrachloride

Carbon tetrachloride, also known by many other names is the organic compound with the chemical formula CCl4. It is a reagent in organic synthesis chemistry and was formerly widely used in fire extinguishers, as a precursor to refrigerations, and a cleaning agent....
places an allylic bromine atom in 1.2 and further bromination with bromine

Bromine

Bromine , , meaning "stench " ), is a chemical element with the symbol Br and atomic number 35. A halogen element, bromine is a reddish-brown Volatility liquid at Standard conditions for temperature and pressure that is intermediate in reactivity between chlorine and iodine....
in pentane

Pentane

Pentane is any or one of the organic compounds with the chemical formula C5H12. This alkane is a component of some fuels and is employed as a specialty solvent in the laboratory....
- methylene chloride gives the tribromide 1.3. Two equivalents of hydrogen bromide

Hydrogen bromide

Hydrogen bromide is the diatomic molecule HydrogenBromine. Under standard conditions, HBr is a gas, but it can be liquified. The aqueous solution hydrobromic acid forms upon dissolving HBr in water....
are eliminated

Elimination reaction

An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one or two-step mechanism ....
from this compound with diethylamine

Diethylamine

Diethylamine is a secondary amine with the molecular structure CH3CH2NHCH2CH3. It is a flammable, strongly alkaline liquid....
in diethyl ether

Diethyl ether

Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic odor....
to bromocyclopentadienone 1.4

In the second part (scheme 2), the spontaneous Diels-Alder dimerization

Diels-Alder reaction

The Diels-Alder reaction is an organic chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system....
of 2.1 to 2.2 is akin the dimerization of cyclopentadiene

Cyclopentadiene

Cyclopentadiene is a chemical compound with the Chemical formula C5H6. This colorless liquid organic chemistry chemical compound has a strong and unpleasant odor....
to dicyclopentadiene

Dicyclopentadiene

Dicyclopentadiene, abbreviated DCPD, is the chemical compound with the formula C10H12. At room temperature, it is a white crystalline solid with a camphor-like odor....
. For the next steps to succeed only the endo isomer should form which it does because the bromine atoms on their approach take up positions as far away from each other and the carbonyl group as possible. In this way the like-dipole interactions are minimized in the transition state

Transition state

The transition state of a chemical reaction is a particular configuration along the reaction coordinate. It is defined as the state corresponding to the highest energy along this reaction coordinate....
for this reaction step. Both carbonyl

Carbonyl

In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double bond to an oxygen atom : C=O.The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex ; in this situation, carbon is triple-bonded to oxygen : C=O....
groups are protected

Protecting group

A protecting group or protective group is introduced into a molecule by chemical modification of a functional group in order to obtain chemoselectivity in a subsequent chemical reaction....
as acetal

Acetal

An acetal is a molecule with two single bonded oxygens attached to the same carbon atom.Traditional usages distinguish ketal from acetal . Current accepted terminology classifies ketals as a subset of acetals....
s with ethylene glycol

Ethylene glycol

Ethylene glycol is an alcohol with two -OH groups , a chemical compound widely used as an automobile antifreeze. In its pure form, it is an odorless, colorless, syrupy, sweet tasting, toxic liquid....
and p-toluenesulfonic acid

P-Toluenesulfonic acid

p-Toluenesulfonic acid is an organic compound with the formula methyl groupbenzeneSulfonic acid. TsOH, as it is abbreviated, is a white solid that is soluble in water, alcohols, and other Chemical polarity organic solvents....
in benzene

Benzene

Benzene, or benzol, is an organic compound chemical compound and a known carcinogen with the molecular formula Carbon6Hydrogen6....
and then one of them is selectively deprotected with aqueous hydrochloric acid

Hydrochloric acid

Hydrochloric acid is the solution of hydrogen chloride in water. It is a highly corrosive, strong acid mineral acid and has major industrial uses....
to 2.3

In the next step endo isomer 2.3 with both alkene

Alkene

In organic chemistry, an alkene, olefin, or olefine is an Saturation chemical compound containing at least one carbon-to-carbon double bond....
groups in close proximity forms the cage-like isomer 2.4 in a photochemical [2+2] cycloaddition

Cycloaddition

A cycloaddition is a pericyclic chemical reaction, in which two pi bond are lost and two sigma bond are gained. The resulting reaction is a cyclization reaction....
. The bromoketone

Haloketone

A haloketone in organic chemistry is a functional group consisting of a ketone group or more general a carbonyl group with a a-halogen substituent....
group is converted to ring-contracted carboxylic acid

Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the Chemical formula -COH, usually written -COOH or -CO2H....
2.5 in a Favorskii rearrangement

Favorskii rearrangement

The Favorskii rearrangement , named for the Russian chemist Alexei Yevgrafovich Favorskii, is most principally a rearrangement of cyclopropanones and a-halo ketones which leads to carboxylic acid derivatives....
with potassium hydroxide

Potassium hydroxide

Potassium hydroxide is the inorganic compound with the formula potassiumhydroxide. Along with sodium hydroxide, this colourless solid is a prototypical "strong base"....
. Next the thermal decarboxylation

Decarboxylation

Decarboxylation is any chemical reaction in which a carboxyl group is split off from a compound as carbon dioxide ....
takes place through the acid chloride (with thionyl chloride

Thionyl chloride

Thionyl chloride is an inorganic compound with the chemical formula SulfurOxygenChlorine2. It is a reactive chemical reagent used in chlorination chemical reaction....
) and the tert-butyl perester 2.6 (with t-butyl hydroperoxide and pyridine

Pyridine

Pyridine is a simple and important heterocyclic aromatic organic compound with the formula CarbonHydrogenNitrogen. This colorless liquid with a distinctive fish-like odor is structurally related to benzene, wherein one CH group in the six-membered ring is replaced by a nitrogen atom....
) to 2.7. then the acetal is once more removed in 2.8, another Favorskii rearrangement gives 2.9 and finally another decarboxylation 2.10 and 2.11.

Inorganic cubes and related derivatives

The cube motif occurs outside of the area of organic chemistry. Prevalent non-organic cubes are the [Fe₄-S₄] clusters found pervasively iron-sulfur protein

Iron-sulfur protein

Iron-sulfur proteins are proteins characterized by the presence of iron-sulfur clusters containing sulfide-linked di-, tri-, and tetrairon centers in variable oxidation states....
s. Such species contain sulfur and Fe at alternating corners. Alternatively such inorganic cube clusters can often be viewed as interpenetrated S₄ and Fe₄ tetrahedra. Many organometallic compounds adopt cube structures, examples being (CpFe)₄(CO)₄, (Cp*Ru)₄Cl₄, and (Ph₃P

Triphenylphosphine

Triphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PhosphorusPhenyl group or Ph3P....
Ag)₄I₄,

Reactions

Cuneane

Cuneane is a saturated hydrocarbon . Its name is derived from the Latin ?cuneus?, meaning a wedge. Cuneane may be produced from cubane by metal-ion-catalyzed s-bond rearrangement....
may be produced from cubane by metal-ion-catalyzed s-bond rearrangement

Metal-ion-catalyzed s-bond rearrangement

The metal-ion-catalyzed s-bond Rearrangement reaction reaction occurs with highly saturated organic ring molecules treated by Ag+, Rh, or Pd ions....
.

Cubane

Synthesis

Inorganic cubes and related derivatives

Reactions

External links