Thiophene
General
Systematic name	Thiophene
Other names	Thiofuran Thiacyclopentadiene
Molecular formula	C4H4S
SMILES	C1=CC=CS1
Molar mass	84.14 g/mol
Appearance	colorless liquid
CAS number	[110-02-1]
Properties
Density and phase	1.051 g/ml, liquid
Solubility	Immiscible with water soluble in most organic solvents
Melting point	−38 °C
Boiling point	84 °C
Viscosity	? cP at ? °C
Dipole moment	? D
Hazards
MSDS	External MSDS
EU classification	not listed
NFPA 704	Image File history File links Chemical structure of thiophene selfmade by cacycle File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... 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. ... 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 at a given pressure. ... The pitch drop experiment at the University of Queensland. ... The poise (P) is the cgs unit of viscosity, 1 P = 1 g·cm-1·s-1 The SI analog is 1 pascal second (Pa·s) = 1 kg·m-1·s-1 = 10 P. It is named after Jean Louis Marie Poiseuille. ... 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. ... Image File history File links NFPA_704. ... 3 2 0
Flash point	−1 °C
RTECS number	XM7350000
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 thioethers	Tetrahydrothiophene Diethyl sulfide
Related compounds	Furan Pyrrole
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Thiophene is an aromatic heterocyclic compound consisting of four carbon atoms and one sulfur atom in a five-membered ring. Compounds analogous to thiophene include furan and pyrrole where the S atom is replaced by O and NH, respectively. Thiophene was discovered by Viktor Meyer in 1871 as a contaminant in benzene. Related to thiophene are benzothiophene and dibenzothiophene, containing the thiophene ring fused with one and two benzene rings, respectively. The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture 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 (or index of refraction) of a material is the factor by which the phase velocity of electromagnetic radiation is slowed in that material, relative to its velocity in a 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 most commonly known as NMR Spectroscopy is the name given to the technique which exploits the magnetic properties of nuclei. ... Basic schematic of mass spectrometry Mass spectrometry is an analytical technique used to measure the mass-to-charge ratio of ions. ... A thioether (also known as a sulfide) is a functional group in organic chemistry that has the structure R-S-R, where R is any organic group. ... Tetrahydrothiophene is a heterocyclic organic compound consisting of a five-membered ring containing four carbon atoms and a sulfur atom. ... Furan, also known as furane and furfuran, is an aromatic heterocyclic organic compound, produced when wood, especially pine-wood, is distilled. ... Pyrrole, or pyrrol, is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H5N. Pyrroles are components of larger aromatic rings, including the porphyrins of heme, the chlorins and bacteriochlorins of chlorophyll, and the corrin ring of vitamin B12. ... In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals) and 25 degrees Celsius (298. ... Aromaticity is a chemical property 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. ... Heterocyclic compounds are substances which contain a ring structure as found in benzene and the aromatic compounds, or aromatic hydrocarbons, but in which other atoms than carbon, such as sulfur, oxygen or nitrogen are found as part of the ring. ... Furan, also known as furane and furfuran, is an aromatic heterocyclic organic compound, produced when wood, especially pine-wood, is distilled. ... Pyrrole, or pyrrol, is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H5N. Pyrroles are components of larger aromatic rings, including the porphyrins of heme, the chlorins and bacteriochlorins of chlorophyll, and the corrin ring of vitamin B12. ... Viktor Meyer (8 September 1848 - 8 August 1897) was a German chemist and significant contributor to knowledge of both organic and inorganic chemistry. ... Benzothiophene is an aromatic organic compound with a molecular formula C8H6S and an odor similar to naphthalene (mothballs). ...

Properties

At room temperature, thiophene is a colorless liquid with a mildly pleasant odor reminiscent of benzene, with which thiophene shares some similarities. Benzene, also known as C6H6, PhH, and benzol, is an organic chemical compound that is a colorless and flammable liquid with a pleasant, sweet smell. ...

Thiophene is considered aromatic, although theoretical calculations suggest that the degree of aromaticity is less than that of benzene. The participation of the lone electron pairs on sulfur in the delocalized pi electron system is significant. As a consequence of its aromaticity, thiophene does not exhibit the properties seen for conventional thioethers. For example the sulfur atom binds weakly to metals. Whereas the sulfur atom is unreactive, the flanking CH centers are susceptible to electrophilic reactions. The high reactivity of thiophene toward sulfonation is the basis for the separation of thiophene from benzene, since these two species cannot typically be separated by distillation due to the mere 4 °C difference in their boiling points at ambient pressure. In chemistry, delocalized electrons are electrons in a molecule that do not belong to a single atom or a covalent bond. ... Geometry of the water molecule Molecules have fixed equilibrium geometries--bond lengths and angles--that are dictated by the laws of quantum mechanics. ... A thioether (also known as a sulfide) is a functional group in organic chemistry that has the structure R-S-R, where R is any organic group. ...

Uses

Thiophenes are important heterocyclic compounds and are recurring building blocks in organic chemistry with applications in pharmaceuticals. For example, thiophenes are used as synthetic intermediates, taking advantage of the susceptability of the carbon atoms adjacent to S toward electrophilic reactions. Desulfurization of the resulting ring using Raney nickel affords 1,4-disubstituted butanes. The polymer formed by linking thiophene through its 1,5 positions is called polythiophene. Polythiophenes become electrically conductive upon partial oxidation, i.e. they become "organic metals". Raney nickel is an amorphous solid composed of finely divided grains of a nickel/aluminium alloy. ... Polythiophenes (PTs) are sulfur heterocycle polymers of thiophene which can become conducting when electrons are added or removed from the conjugated π-orbitals via doping. ...

Thiophene is used as a denaturant for ethanol with which it forms an azeotrope. Ethanol, also known as ethyl alcohol or grain alcohol, is a flammable, colorless chemical compound, one of the alcohols that is most often found in alcoholic beverages. ... An azeotrope is a liquid mixture of two or more components which has a unique constant boiling point. ...

Synthesis and occurrence

Reflecting their high stabilities, thiophenes arise from many reactions involving sulfur sources and hydrocarbons, especially unsaturated ones, e.g. acetylenes and elemental sulfur. Thiophenes are classically prepared by the reaction of 1,4-diketones with sulfiding reagents such as Lawesson's reagent or P₄S₁₀. Specialized thiophenes can be synthesized via the Gewald reaction, which involves the condensation of two esters in the presence of elemental suflur. Ketone group A ketone is either the functional group characterized by a carbonyl group linked to two other carbon atoms or a chemical compound that contains this functional group. ... Lawessons reagent or LR is a chemical compound used in organic synthesis as a thiation agent. ... The Gewald reaction is a chemical reaction involving the condensation of a ketone (or aldehyde when R2 = H) with a α-cyanoester in the presence of elemental sulfur to give a tetra-substituted thiophene. ... For the Biblical Ester, see Esther. ...

Thiophene and its derivatives occur in petroleum, sometimes in concentrations up to 1-3 %. The thiophenic content of liquids from oil and coal is removed via the hydrodesulfurization (HDS) process. In HDS, the liquid or gaseous feed is passed over a special form of molybdenum disulfide under a pressure of H₂. Thiophenes undergo hydrogenolysis to form hydrocarbons and hydrogen sulfide. Thus, thiophene itself is converted to butane and H₂S. More prevalent and more problematic in petroleum are benzothiophene and dibenzothiophene. Pumpjack pumping an oil well near Sarnia, Ontario Petroleum (from Greek petra – rock and elaion – oil or Latin oleum – oil ) or crude oil, sometimes colloquially called black gold, is a thick, dark brown or greenish liquid. ... A liquid will assume the shape of its container. ... Pumpjack pumping an oil well near Sarnia, Ontario Petroleum (from Greek petra – rock and elaion – oil or Latin oleum – oil ) or crude oil, sometimes colloquially called black gold, is a thick, dark brown or greenish liquid. ... Coal (previously referred to as pitcoal or seacoal) is a fossil fuel extracted from the ground by underground mining or open-pit mining (surface mining). ... Hydrodesulfurization is one means of lowering the sulfur content of liquids from oil/coal. ... Molybdenum disulfide, also called molybdenum sulfide or molybdenum(IV) sulfide, with the formula MoS2, is a black crystalline sulfide of molybdenum. ... In chemistry, a hydrocarbon is a cleaning solution consisting only of carbon (C) and hydrogen (H). ... Flash point -82. ... Benzothiophene is an aromatic organic compound with a molecular formula C8H6S and an odor similar to naphthalene (mothballs). ...

See also

• Pyrrole, an analog with a NH instead of the sulfur atom.
• Furan, an analog with an oxygen instead of the sulfur atom.
• Simple aromatic rings

Pyrrole, or pyrrol, is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H5N. Pyrroles are components of larger aromatic rings, including the porphyrins of heme, the chlorins and bacteriochlorins of chlorophyll, and the corrin ring of vitamin B12. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Atomic mass 32. ... Properties In chemistry and physics, an atom (Greek άτομον meaning indivisible) is the smallest possible particle of a chemical element that retains its chemical properties. ... Furan, also known as furane and furfuran, is an aromatic heterocyclic organic compound, produced when wood, especially pine-wood, is distilled. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Simple aromatic rings are aromatic organic compounds (also known as arenes or aromatics) that consist only of conjugated planar ring systems with delocalized pi electron clouds instead of discrete alternating single and double bonds. ...

External links

• International Chemical Safety Card 1190
• [1] Roncali, J., "Conjugated Poly(thiophenes): Synthesis, Functionalization, and Applications", Chemical Reviews, 1992, v. 92, p 711-738.