Cyclopropane
Overview
 
Cyclopropane is a cycloalkane
Cycloalkane
Cycloalkanes are types of alkanes that have one or more rings of carbon atoms in the chemical structure of their molecules. Alkanes are types of organic hydrocarbon compounds that have only single chemical bonds in their chemical structure...

 molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 with the molecular formula C3H6, consisting of three carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 atoms linked to each other to form a ring, with each carbon atom bearing two hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 atoms. Cyclopropane and propene have the same molecular formula but have different structures, making them structural isomers.

The bonds
Chemical bond
A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...

 between the carbon atoms are considerably weaker than in a typical carbon-carbon bond, yielding reactivity similar to or greater than alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

s.
Encyclopedia
Cyclopropane is a cycloalkane
Cycloalkane
Cycloalkanes are types of alkanes that have one or more rings of carbon atoms in the chemical structure of their molecules. Alkanes are types of organic hydrocarbon compounds that have only single chemical bonds in their chemical structure...

 molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 with the molecular formula C3H6, consisting of three carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 atoms linked to each other to form a ring, with each carbon atom bearing two hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 atoms. Cyclopropane and propene have the same molecular formula but have different structures, making them structural isomers.

The bonds
Chemical bond
A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...

 between the carbon atoms are considerably weaker than in a typical carbon-carbon bond, yielding reactivity similar to or greater than alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

s. Baeyer strain theory
Baeyer strain theory
Baeyer strain theory or strain theory explains specific behaviour of chemical compounds in terms of bond angle strain.It was proposed by Adolf von Baeyer in 1885 to account for the unusual chemical reactivity in ring-opening reactions of cyclopropanes and cyclobutanes where this angle strain is...

 explains why: The angle strain
Angle strain
Angle strain, also called Baeyer strain in cyclic molecules, is the resistance associated with bond angle compression or bond angle expansion. It occurs when bond angles deviate from the ideal bond angles to achieve maximum bond strength in a specific chemical conformation...

 from the 60° angle between the carbon atoms (less than the normal angle of 109.5° for bonds between atoms with sp3 hybridised orbitals) reduces the compound's carbon-carbon bond energy, making it more reactive than other cycloalkane
Cycloalkane
Cycloalkanes are types of alkanes that have one or more rings of carbon atoms in the chemical structure of their molecules. Alkanes are types of organic hydrocarbon compounds that have only single chemical bonds in their chemical structure...

s such as cyclohexane
Cyclohexane
Cyclohexane is a cycloalkane with the molecular formula C6H12. Cyclohexane is used as a nonpolar solvent for the chemical industry, and also as a raw material for the industrial production of adipic acid and caprolactam, both of which being intermediates used in the production of nylon...

 and cyclopentane
Cyclopentane
Cyclopentane is a highly flammable alicyclic hydrocarbon with chemical formula 510 and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and below the plane. It occurs as a colorless liquid with a petrol-like odor. Its melting point is −94 °C...

. The molecule also has torsional strain due to the eclipsed conformation of its hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 atoms. It is somewhat stabilized by some pi character in its carbon-carbon bonds, indicated by the Walsh orbital description whereas it is modeled as a three-center-bonded orbital combination of methylene carbene
Carbene
In chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is RR'C:, but the carbon can instead be double-bonded to one group. The term "carbene" may also merely refer to the compound H2C:, also called...

s . Bent bonds also describe the bonding in cyclopropane.

The smallest polycyclic compound
Polycyclic compound
In organic chemistry, a polycyclic compound is a cyclic compound with more than one hydrocarbon loop or ring structures . In general, the term includes all polycyclic aromatic compounds, including the polycyclic aromatic hydrocarbons, the heterocyclic aromatic compounds containing sulfur,...

s contain multiple fused cyclopropane rings. Tetrahedrane
Tetrahedrane
Tetrahedrane is a platonic hydrocarbon with chemical formula 44 and a tetrahedral structure. Extreme angle strain prevents this molecule from forming naturally....

 contains four fused cyclopropane rings that form the faces of a tetrahedron
Tetrahedron
In geometry, a tetrahedron is a polyhedron composed of four triangular faces, three of which meet at each vertex. A regular tetrahedron is one in which the four triangles are regular, or "equilateral", and is one of the Platonic solids...

. [1.1.1]Propellane
1.1.1-Propellane
[1.1.1]Propellane is an organic compound, the simplest member of the propellane family. It is a hydrocarbon with formula C5H6 or C23. The molecular structure consists of three rings of three carbon atoms each, sharing one C-C bond....

 contains three cyclopropane rings that share a single central carbon-carbon bond.

Cyclopropane is an anaesthetic when inhaled. In modern anaesthetic practice, it has been superseded by other agents, due to its extreme reactivity under normal conditions: When the gas is mixed with oxygen there is a significant risk of explosion.

History

Cyclopropane was discovered in 1881 by August Freund
August Freund
August Freund was an Austrian chemist. In 1881 he discovered the mechanism for synthesising cyclopropane. The method now bears his name. He was able to synthesise enough cyclopropane to do several chemical reactions and derive from the results the three-membered ring structure of cyclopropane.-...

, who also proposed the correct structure for the new substance in his first paper. Freund treated 1,3-dibromopropane
1,3-Dibromopropane
1,3-Dibromopropane is a halogenated hydrocarbon. When at room temperature, it is a colorless to light-brown liquid. Synthetically, it is very useful to form C3-bridged compounds such as through C-N coupling reactions....

 with sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

, the reaction is an intramolecular Wurtz reaction
Wurtz reaction
The Wurtz reaction, named after Charles-Adolphe Wurtz, is a coupling reaction in organic chemistry, organometallic chemistry and recently inorganic main group polymers, whereby two alkyl halides are reacted with sodium to form a new carbon-carbon bond:...

 leading directly to cyclopropane.
The yield of the reaction can be improved by the use of zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

 instead of sodium. Cyclopropane had no commercial application until Henderson and Lucas discovered its anaesthetic properties in 1929; industrial production had begun by 1936.

Safety

Because of the strain
Strain (chemistry)
In chemistry, a molecule experiences strain when its chemical structure undergoes some stress which raises its internal energy in comparison to a strain-free reference compound. The internal energy of a molecule consists of all the energy stored within it. A strained molecule has an additional...

 in the carbon-carbon bonds of cyclopropane, the molecule has an amount of potential energy
Potential energy
In physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. The SI unit of measure for energy and work is the Joule...

, indicated by its high heat of combustion. In pure form, it will break down to form linear hydrocarbons, including "normal", non-cyclic propene. This decomposition is potentially explosive, especially if the cyclopropane is liquified, pressurized, or contained within tanks. Explosions of cyclopropane and oxygen are even more powerful, because the energy released by the formation of propene is compounded by the energy released via the oxidation of the carbon and hydrogen present.

At room temperature, sufficient volumes of liquified cyclopropane will self-detonate. To guard against this, the liquid is shipped in cylinders filled with tungsten
Tungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...

 wool, which improves stability. Pipes to carry cyclopropane must likewise be of small diameter, or else filled with unreactive metal or glass wool
Glass wool
Glass wool or fiberglass insulation is an insulating material made from fiberglass, arranged into a texture similar to wool. Glass wool is produced in rolls or in slabs, with different thermal and mechanical properties....

, to prevent explosions. Even if these precautions are followed, cyclopropane is dangerous to handle and manufacture, and is no longer used for anaesthesia.

Cyclopropanes

Cyclopropanes are a class of organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

s containing a cyclopropane ring, in which one or more hydrogen atoms are replaced by other groups. These compounds are found in biomolecule
Biomolecule
A biomolecule is any molecule that is produced by a living organism, including large polymeric molecules such as proteins, polysaccharides, lipids, and nucleic acids as well as small molecules such as primary metabolites, secondary metabolites, and natural products...

s and many synthetic substances. For instance, the pyrethrum insecticide
Pyrethrin
The pyrethrins are a pair of natural organic compounds that have potent insecticidal activity. Pyrethrins are neurotoxins that attack the nervous systems of all insects. When present in amounts not fatal to insects, they still appear to have an insect repellent effect. Pyrethrins are gradually...

s found in certain Chrysanthemum
Pyrethrum
Pyrethrum refers to several Old World plants of the genus Chrysanthemum which are cultivated as ornamentals for their showy flower heads. Pyrethrum is also the name of a natural insecticide made from the dried flower heads of C. cinerariifolium and C...

 species contain a cyclopropane ring. Many modified derivatives, called pyrethroid
Pyrethroid
A pyrethroid is an organic compound similar to the natural pyrethrins produced by the flowers of pyrethrums . Pyrethroids now constitute a major commercial household insecticides...

s, have been prepared.

Organic synthesis

Cyclopropanes can be prepared in the laboratory by 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 molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

 in various ways and many methods are simply called cyclopropanation.

By coupling

Cyclopropanes can be obtained by an intramolecular coupling reaction
Coupling reaction
A coupling reaction in organic chemistry is a catch-all term for a variety of reactions where two hydrocarbon fragments are coupled with the aid of a metal catalyst...

 in the addition of sodium to 1,3-dibromopropane in the Freund reaction (1881) or zinc to 1,3-dichloropropane in the Gustavson reaction (1887):
BrCH2CH2CH2Br + 2 Na → (CH2)3 + 2 NaBr

Related is the intramolecular Wurtz coupling examplified by the synthesis of bicyclo[1.1.0]butane.

From alkenes

The addition to an alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

 of a zinc carbenoid takes place in the Simmons-Smith reaction
Simmons-Smith reaction
The Simmons–Smith reaction is an organic cheletropic reaction in which a carbenoid reacts with an alkene to form a cyclopropane. It is named after Howard Ensign Simmons, Jr. and R. D. Smith...

 (1958) for example to cinnamyl alcohol
Cinnamyl alcohol
Cinnamyl alcohol is an organic compound that is found in esterified form in storax, balsam Peru and cinnamon leaves. It forms a white crystalline solid when pure, or a yellow oil when even slightly impure. It can be produced by the hydrolysis of storax....

. In one adaptation an amide
Amide
In chemistry, an amide is an organic compound that contains the functional group consisting of a carbonyl group linked to a nitrogen atom . The term refers both to a class of compounds and a functional group within those compounds. The term amide also refers to deprotonated form of ammonia or an...

 is reacted with two equivalents of dichloromethane
Dichloromethane
Dichloromethane is an organic compound with the formula CH2Cl2. This colorless, volatile liquid with a moderately sweet aroma is widely used as a solvent. Although it is not miscible with water, it is miscible with many organic solvents...

 aided by titanium tetrachloride
Titanium tetrachloride
Titanium tetrachloride is the inorganic compound with the formula TiCl4. It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. TiCl4 is an unusual example of a metal halide that is highly volatile...

 and magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

:
a possible reaction mechanism
Reaction mechanism
In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical change occurs.Although only the net chemical change is directly observable for most chemical reactions, experiments can often be designed that suggest the possible sequence of steps in...

 for this cyclopropanation was proposed:


The carbene can also be a regular carbene such as dibromocarbene in the synthesis of propellane
Propellane
In organic chemistry, propellane is any member of a class of polycyclic hydrocarbons, whose carbon skeleton consists of three rings of carbon atoms sharing a common carbon-carbon covalent bond...

 or carbene precursor methyl diazoacetate

The addition of a carbene to an alkene is a form of cheletropic reaction
Cheletropic reaction
thumb|300px|right|Pericyclic ReactionsCheletropic reactions are a type of pericyclic reaction. A pericyclic reaction is one that involves a transition state with a cyclic array of atoms and an associated cyclic array of interacting orbitals. A reorganization of σ and π bonds occurs in this cyclic...

. Intermolecular metal-catalyzed carbenoid cyclopropanations
Intermolecular metal-catalyzed carbenoid cyclopropanations
Intermolecular metal-catalyzed carbenoid cyclopropanations are organic reactions that result in the formation of a cyclopropane ring from a metal carbenoid species and an alkene....

 are also known.

By nucleophilic displacement

In nucleophilic displacement a leaving group
Leaving group
In chemistry, a leaving group is a molecular fragment that departs with a pair of electrons in heterolytic bond cleavage. Leaving groups can be anions or neutral molecules. Common anionic leaving groups are halides such as Cl−, Br−, and I−, and sulfonate esters, such as para-toluenesulfonate...

 is displaced by a carbon nucleophile
Nucleophile
A nucleophile is a species that donates an electron-pair to an electrophile to form a chemical bond in a reaction. All molecules or ions with a free pair of electrons can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases.Nucleophilic describes the...

 in a 1,3 relationship, for example the synthesis of cyclopropylacetylene from 5-chloro-1-pentyne. Another example can be found in the Bingel reaction
Bingel reaction
The Bingel reaction in fullerene chemistry is a fullerene cyclopropanation reaction to a methanofullerene first discovered by C. Bingel in 1993 with the bromo derivative of diethyl malonate in the presence of a base such as sodium hydride or DBU...

. An asymmetric reaction creating three stereocenter
Stereocenter
A stereocenter or stereogenic center is an atom, bearing groups such that an interchanging of any two groups leads to a stereoisomer.A chirality center is a stereocenter consisting of an atom holding a set of ligands in a spatial arrangement which is not superposable on its mirror image...

s is demonstrated in a reaction of cyclohexenone
Cyclohexenone
Cyclohexenone is an organic compound which is a versatile intermediate used in the synthesis of a variety of chemical products such as pharmaceuticals and fragrances...

 with bromonitromethane
Nitromethane
Nitromethane is an organic compound with the chemical formula . It is the simplest organic nitro compound. It is a slightly viscous, highly polar liquid commonly used as a solvent in a variety of industrial applications such as in extractions, as a reaction medium, and as a cleaning solvent...

 assisted by trans-2,5-dimethylpiperazine
Piperazine
Piperazine is an organic compound that consists of a six-membered ring containing two opposing nitrogen atoms. Piperazine exists as small alkaline deliquescent crystals with a saline taste....

 as a base and a pyrrolidine
Pyrrolidine
Pyrrolidine, also known as tetrahydropyrrole, is an organic compound with the molecular formula C4H9N. It is a cyclic secondary amine with a five-membered heterocycle containing four carbon atoms and one nitrogen atom...

 based tetrazole
Tetrazole
Tetrazoles are a class of synthetic organic heterocyclic compound, consisting of a 5-member ring of four nitrogen and one carbon atom . The simplest is tetrazole itself, CN4H2. They are unknown in nature...

 organocatalyst:

Rearrangements

Rearrangement reaction
Rearrangement reaction
A rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. Often a substituent moves from one atom to another atom in the same molecule...

 of certain cyclobutane
Cyclobutane
Cyclobutane is an organic compound with the formula 4. Cyclobutane is a colourless gas and commercially available as a liquefied gas. Derivatives of cyclobutane are called cyclobutanes...

 compounds can result in cyclopropanes for instance the conversion of 1,2-cyclobutanediol to cyclopropanecarboxaldehyde, the di-pi-methane rearrangement
Di-pi-methane rearrangement
The di-pi-methane rearrangement is a photochemical reaction of a molecular entity comprising two π-systems, separated by a saturated carbon atom , to form an ene- substituted cyclopropane...

 is a
photochemical rearrangement reaction
Rearrangement reaction
A rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. Often a substituent moves from one atom to another atom in the same molecule...

 of 1,4-dienes to vinylcyclopropanes

Other

In the Kulinkovich reaction
Kulinkovich reaction
The Kulinkovich reaction describes the organic synthesis of cyclopropanols via reaction of esters with dialkyldialkoxytitanium reagents, generated in situ from Grignard reagents bearing hydrogen in beta-position and titanium alkoxides such as titanium isopropoxide. This reaction was discovered by...

 esters react with Grignards in presence of a titanium alkoxide. Extrusion of nitrogen takes place in certain pyrazolines in the so called Kishner cyclopropane synthesis

Organic reactions

Although cyclopropanes are formally cycloalkane
Cycloalkane
Cycloalkanes are types of alkanes that have one or more rings of carbon atoms in the chemical structure of their molecules. Alkanes are types of organic hydrocarbon compounds that have only single chemical bonds in their chemical structure...

s, they are very reactive due to considerable strain energy
Strain 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,...

 and due to double bond
Double bond
A double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...

 character.

Electrophilic addition

Cyclopropanes react with mineral acid
Mineral acid
A mineral acid is an acid derived from one or more inorganic compounds. A mineral acid is not organic and all mineral acids release hydrogen ions when dissolved in water.-Characteristics:...

s such as HX in electrophilic addition
Electrophilic addition
In organic chemistry, an electrophilic addition reaction is an addition reaction where, in a chemical compound, a π bond is broken and two new σ bonds are formed...

 (very much like a double bond) to linear alkyl halides with ring-opening. Substituted cyclopropanes follow Markovnikov's rule
Markovnikov's rule
In organic chemistry, Markovnikov's rule or Markownikoff's rule is an observation based on Zaitsev's rule. It was formulated by the Russian chemist Vladimir Vasilevich Markovnikov in 1870....

.

Cycloadditions

Cyclopropyl groups participate in cycloaddition
Cycloaddition
A cycloaddition is a pericyclic chemical reaction, in which "two or more unsaturated molecules combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity." The resulting reaction is a cyclization reaction.Cycloadditions are usually described by the...

 reactions such as the formal [5+2]cycloaddition shown below:

This asymmetric synthesis is catalyzed by a rhodium
Rhodium
Rhodium is a chemical element that is a rare, silvery-white, hard and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. It is composed of only one isotope, 103Rh. Naturally occurring rhodium is found as the free metal, alloyed...

 BINAP
BINAP
BINAP is an abbreviation for the organophosphorus compound 2,2'-bis-1,1'-binaphthyl. This chiral ligand is widely used in asymmetric synthesis. It consists of a pair of 2-diphenylphosphinonaphthyl groups linked at the 1 and 1´ positions. This C2-symmetric framework lacks stereogenic atom, but...

 system with 96% enantiomeric excess
Enantiomeric excess
The enantiomeric excess of a substance is a measure of how pure it is. In this case, the impurity is the undesired enantiomer .-Definition:...

. Also see the vinylcyclopropane rearrangement
Vinylcyclopropane rearrangement
The vinylcyclopropane rearrangement or vinylcyclopropane-cyclopentene rearrangement is a ring expansion reaction, converting a vinyl-substituted cyclopropane ring into a cyclopentene ring. The general scope is extended by introducing heteroatoms in any of the 5 framework positions or by replacing...

 and the divinylcyclopropane-cycloheptadiene rearrangement
Divinylcyclopropane-cycloheptadiene rearrangement
The divinylcyclopropane-cycloheptadiene rearrangement is an organic chemical transformation that involves the isomerization of a 1,2-divinylcyclopropane into a cycloheptadiene or -triene...

.

Rearrangements

Cyclopropyl groups also engage in many rearrangement reaction
Rearrangement reaction
A rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. Often a substituent moves from one atom to another atom in the same molecule...

s. An extreme example is found in the compound bullvalene
Bullvalene
Bullvalene is a hydrocarbon with the chemical formula C10H10 with the unusual property that the chemical bonds making up the molecule are constantly rearranging as in fluxional molecules...

. A cyclopropane ring is an intermediate in the Favorskii rearrangement
Favorskii rearrangement
The Favorskii rearrangement , named for the Russian chemist Alexei Yevgrafovich Favorskii, is most principally a rearrangement of cyclopropanones and α-halo ketones which leads to carboxylic acid derivatives. In the case of cyclic α-halo ketones, the Favorski rearrangement constitutes a ring...

. Certain methylenecyclopropanes are found to convert to cyclobutene
Cyclobutene
Cyclobutene is a cycloalkene. It is used in the chemical industry as a monomer for synthesis of some polymers and for a range of chemical syntheses.- External links :*...

s:

This reaction is catalyzed by platinum(II) chloride
Platinum(II) chloride
Platinum chloride is the chemical compound PtCl2. It is an important precursor used in the preparation of other platinum compounds. It exists in two crystalline forms, but the main properties are somewhat similar: dark brown, insoluble in water, diamagnetic, and odorless.-Structure:The...

 in a carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

 environment. The proposed reaction mechanism
Reaction mechanism
In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical change occurs.Although only the net chemical change is directly observable for most chemical reactions, experiments can often be designed that suggest the possible sequence of steps in...

 is supported by deuterium labeling.

In another version of the same reaction the catalyst is PdBr2 is prepared in situ
In situ
In situ is a Latin phrase which translated literally as 'In position'. It is used in many different contexts.-Aerospace:In the aerospace industry, equipment on board aircraft must be tested in situ, or in place, to confirm everything functions properly as a system. Individually, each piece may...

 from palladium(II) acetate
Palladium(II) acetate
Palladium acetate is a chemical compound of palladium described by the formula Pd2 or Pd2. It is considered more reactive than the analogous platinum compound...

 and copper(II) bromide
Copper(II) bromide
Copper bromide is a chemical compound. It is used in photographic processing as an intensifier and as a brominating agent in organic synthesis....

 and the solvent is toluene
Toluene
Toluene, formerly known as toluol, is a clear, water-insoluble liquid with the typical smell of paint thinners. It is a mono-substituted benzene derivative, i.e., one in which a single hydrogen atom from the benzene molecule has been replaced by a univalent group, in this case CH3.It is an aromatic...

.

Molecular orbitals

Bonding between the carbon centers in cyclopropane is generally described by invoking bent bonds.

External links

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