Cyclopentadiene
General
Systematic name	1,3-cyclopentadiene
Other names	cyclopentadien, pentole, pyropentylene
Molecular formula	C5H6
SMILES	C1C=CC=CC1
Molar mass	66.10 g/mol
Appearance	colourless liquid
CAS number	[542-92-7]
Properties
Density and phase	0.81 g/cm3, liquid
Solubility in hexane, benzene, toluene	miscible
Melting point	-85 °C (188 K)
Boiling point	41 °C (314 K)
Structure
Molecular shape	envelope structure
Dipole moment	? D
Hazards
MSDS	External MSDS
EU classification	not listed
NFPA 704
Flash point	25 °C
RTECS number	GY1000000
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related hydrocarbon	Benzene Cyclobutadiene
Related compounds	Dicyclopentadiene
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references

Cyclopentadiene, with molecular formula C₅H₆, is a clear, colorless, liquid organic chemical, with an odor reminiscent of turpentine or camphor. It is a cyclic diene which slowly dimerizes to form dicyclopentadiene through a Diels-Alder reaction if stored at room temperature. This dimer can be cracked and separated into the monomer by distillation at atmospheric pressure. Image File history File links Cyclopentadiene. ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... The simplified molecular input line entry specification or SMILES is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. ... Molar mass is the mass of one mole of a chemical element or chemical compound. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... Density (symbol: ρ - Greek: rho) is a measure of mass per unit of volume. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... It has been suggested that this article or section be merged with Solution. ... R-phrases , , , , , , S-phrases , , , , , , , Flash point −23. ... Benzene, also known as C6H6, PhH, and benzol, is an organic chemical compound which is a colorless and flammable liquid with a pleasant, sweet smell. ... Toluene, also known as methylbenzene or phenylmethane is a clear water-insoluble liquid with the typical smell of paint thinners, reminiscent of the sweet smell of the related compound benzene. ... The melting point of a solid is the temperature at which it changes state from solid to liquid. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid. ... four sp³ orbitals three sp² orbitals In chemistry, hybridisation is the mixing of atomic orbitals belonging to a same electron shell to form new orbitals suitable for the qualitative description of atomic bonding properties. ... The Earths magnetic field, which is approximately a dipole. ... The debye (symbol: D) is a non-SI and non-CGS unit of electrical dipole moment. ... A material safety data sheet or MSDS is a form containing data regarding the properties of a particular substance. ... Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances (as amended) is the main source of European Union law concerning chemical safety. ... NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. ... The flash point of a fuel is the lowest temperature at which it can form an ignitable mix with air. ... RTECS, also known as Registry of Toxic Effects of Chemical Substances, is a database of toxicity information compiled from the open scientific literature that is available for charge. ... The refractive index of a material is the factor by which the phase velocity of electromagnetic radiation is slowed relative to vacuum. ... The dielectric constant εr (represented as or K in some cases) is defined as the ratio: where εs is the static permittivity of the material in question, and ε0 is the vacuum permittivity. ... Ultraviolet-Visible Spectroscopy or Ultraviolet-Visible Spectrophotometry (UV/ VIS) involves the spectroscopy of photons (spectrophotometry). ... IR spectrum of a thin film of liquid ethanol. ... Nuclear Magnetic Resonance Spectroscopy is the name given to the technique which exploits the magnetic properties of nuclei. ... Mass spectrometry is an analytical technique to measure the mass-to-charge ratio (m/q) of ions. ... Hydrocarbons are refined at oil refineries and chemical plants In chemistry, a hydrocarbon is any chemical compound that consists only of the elements carbon (C) and hydrogen (H). ... Benzene, also known as C6H6, PhH, and benzol, is an organic chemical compound which is a colorless and flammable liquid with a pleasant, sweet smell. ... Cyclobutadiene is the smallest [n]-annulene ([4]-annulene), an extremely unstable hydrocarbon having a lifetime shorter than five seconds in the free state. ... Dicyclopentadiene, C10H12, is a hydrocarbon found in oil deposits. ... In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals) and 25 degrees Celsius (298. ... In general, a molecule is the smallest particle of a pure chemical substance that still retains its composition and chemical properties. ... In chemistry, the empirical formula of a chemical is a simple expression of the relative number of each type of atom (called a chemical element) in it. ... Organic chemistry is the scientific study of the structure, properties, composition, reactions, and synthesis of organic compounds that by definition contain carbon. ... A chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. ... Dienes are hydrocarbons which contain two double bonds. ... Sucrose, or common table sugar, is composed of glucose and fructose. ... Dicyclopentadiene, C10H12, is a hydrocarbon found in oil deposits. ... The Diels-Alder reaction is an organic chemical reaction (specifically, a cycloaddition) between a conjugated diene and a substituted alkene, commonly termed the dienophile to form a substituted cyclohexene system. ...

Deprotonation yields the five-membered aromatic hydrocarbon cyclopentadienyl anion, C₅H₅⁻, which can combine with a number of different transition metals to form cyclopentadienyl complexes, such as metallocenes. Deprotonation is a chemistry term that refers to the removal of a proton (hydrogen ion H+) from a molecule, forming the conjugate base. ... In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... Hydrocarbons are refined at oil refineries and chemical plants In chemistry, a hydrocarbon is any chemical compound that consists only of the elements carbon (C) and hydrogen (H). ... An anion is an ion with negative charge. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... In chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings: It commonly refers to any element in the d-block of the periodic table, including zinc and scandium. ... A cyclopentadienyl complex is a metal complex with one or more cyclopentadienyl groups (C5H5-, abbreviated as Cp). ... In chemistry, and in particular, in organometallic chemistry, a metallocene is a compound consisting of an aromatic organic ligand bound to a metal. ...

The delocalization energy gained by proton loss makes this compound weakly acidic, which is unusual for a hydrocarbon. An acid (from Arabic Azait meaning oil, often represented by the generic formula AH) is typically a water-soluble, sour-tasting chemical compound. ...

Monomeric cyclopentadiene's methylene hydrogens rapidly undergo [1,5] sigmatropic shifts and occupy positions at all carbons; at room temperature the NMR spectrum appears as a single peak at 4.8 ppm. At cooler temperatures, these resolve into peaks at 4.0, 5.2, and 5.4 ppms, which reflect the static structure drawn in most depictions of cyclopentadiene. NMR may refer to: Nuclear magnetic resonance, a phenomenon involving the interaction of atomic nuclei and external magnetic fields Nielsen Media Research, a U.S. company which measures TV, radio and newspaper audiences This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the...

Metal-organic chemistry

Alkali metal bases can deprotonate cyclopentadiene to form the alkali metal derivatives of the cyclopentadienyl anion. Although these polar species are not really salts, they behave as a source of C₅H₅⁻. For example NaC₅H₅ reacts with various metal compounds to form a variety of complexes that are throughout chemistry. The cyclopentadienyl unit, abbreviated Cp, typically bonds to metals through all five carbon atoms, like in ferrocene, [FeCp₂]; chromocene, [CrCp₂]; cobaltocene, [CoCp₂]; and nickelocene, [NiCp₂]. When the Cp rings are mutually parallel the compound is known as a sandwich complex. This area of organometallic chemistry was first discovered in 1954 with the realization of the structure of ferrocene.^[1] Deprotonation is a chemistry term that refers to the removal of a proton (hydrogen ion H+) from a molecule, forming the conjugate base. ... The alkali metals are the series of elements in Group 1 (IUPAC style) of the periodic table, excluding hydrogen: that is, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). ... // An ion is an atom or group of atoms with a net electric charge. ... Chemistry (derived from the Arabic word kimia, alchemy, where al is Arabic for the) is the science that deals with the properties of organic and inorganic substances and their interactions with other organic and inorganic substances. ... --141. ... Ferrocene Fe(C5H5)2 is the prototypical metallocene, a type of organometallic chemical compound, consisting of two cyclopentadienyl rings bound on opposite sides of a central iron atom and forming an organometallic sandwich compound. ... Cobaltocene, Co(C5H5)2, also known as bis(cyclopentadienyl)cobalt(II), belongs to a group of organometallic compounds called metallocenes which consist of a metal ion sandwiched between two cyclopentadienyl (Cp) rings. ... Nickelocene, Ni(C5H5)2, also known as biscyclopentadienylnickel(II), belongs to a group of organometallic compounds called metallocenes which consist of a metal ion sandwiched between two cyclopentadienyl (cp) rings. ... Organometallic chemistry is the study of chemical compounds containing bonds between carbon and a metal. ...

In rare cases, the Cp unit can bond through three carbon atoms, like in [(η³Cp)WCp(CO)₂]; or through one carbon atom, as in [(η¹-Cp)FeCp(CO)₂]. The Greek letter η (eta) is used to denote the number of carbon atoms bound to the metal center, such as with a Cp ring. η¹ means one carbon, η³ means three carbons, and η⁵ means five carbons.^[2]

Other metals form bent structures, such as zirconocene dichloride, [ZrCp₂Cl₂], which is a catalyst for ethylene polymerization. A catalyst (Greek: καταλύτης, catalytÄ“s) is a substance that accelerates the rate (speed) of a chemical reaction (see also catalysis). ... R-phrases R12, R67 S-phrases S2, S9, S16, S33, S46 Flash point Flammable gas Explosive limits 2. ... Polymerization is a process of reacting monomer molecules together in a chemical reaction to form linear chains or a three-dimensional network of polymer chains [1]. There are many forms of polymerization and different systems exist to categorize them. ...

See also

• Aromaticity

In chemistry, an aromatic molecule is one in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone. ...

References

1. ^  Crabtree, R. H. (2001). The Organometallic Chemistry of the Transition Metals (3rd Edn.) New York: John Wiley and Sons.
2. ^  Shriver, D.; Atkins, P. (1999). Inorganic Chemistry, New York: W. H. Freeman.

Other sources

• Girolami, G. S.; Rauchfuss, T. B.; & Angelici, R. J. (1999). Synthesis and Technique in Inorganic Chemistry, A Laboratory Manual (3rd Edn.) Sausalito, CA: University Science Books.
• Streitwieser, A.; Heathcock, C. H.; Kosower, E. M. (1998). Introduction to Organic Chemistry (4th Edn.) Upper Saddle River, NJ: Prentice Hall.
• ChemFinder "Dicyclopentadiene" Accessed 2005-04-13.

2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... 13 April is the 103rd day of the year in the Gregorian calendar (104th in leap years). ...

External links

• International Chemical Safety Card 0857
• NIOSH Pocket Guide to Chemical Hazards