NationMaster - Encyclopedia: Alkane

Alkanes, also known as paraffins, are chemical compounds that consist only of the elements carbon (C) and hydrogen (H) (i.e., hydrocarbons), wherein these atoms are linked together exclusively by single bonds (i.e., they are saturated compounds) without any cyclic structure (i.e. loops). Alkanes belong to a homologous series of organic compounds in which the members differ by a constant relative atomic mass of 14. Image File history File links Methane-2D-stereo. ... Image File history File links Methane-2D-stereo. ... Methane is a chemical compound with the molecular formula . ... For other uses, see Paraffin (disambiguation). ... Look up chemical compound in Wiktionary, the free dictionary. ... For other uses, see Carbon (disambiguation). ... This article is about the chemistry of hydrogen. ... Look up Hydrocarbon in Wiktionary, the free dictionary. ... Covalently bonded hydrogen and carbon in a molecule of methane. ... In chemistry, saturation has four different meanings: In physical chemistry, saturation is the point at which a solution of a substance can dissolve no more of that substance and additional amounts of that substance will appear as a precipitate. ... In chemistry, a homologous series is a series of organic compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group, and shows a gradation in physical properties as a result of increase in molecular size and mass (see relative molecular mass). ...

Each carbon atom must have 4 bonds (either C-H or C-C bonds), and each hydrogen atom must be joined to a carbon atom (H-C bonds). A series of linked carbon atoms is known as the carbon skeleton or carbon backbone. In general, the number of carbon atoms is often used to define the size of the alkane (e.g., C₂-alkane).

An alkyl group is a functional group or side-chain that, like an alkane, consists solely of singly-bonded carbon and hydrogen atoms, for example a methyl or ethyl group. An alkyl is a univalent radical containing only carbon and hydrogen atoms arranged in a chain. ... In organic chemistry, functional groups (or moieties) are specific groups of atoms within molecules, that are responsible for the characteristic chemical reactions of those molecules. ... In chemistry a methyl-group is a hydrophobic Alkyl functional group which is derived from methane (CH4). ... In chemistry, an ethyl group is an alkyl functional group derived from ethane (C2H6). ...

Saturated hydrocarbons can be linear (general formula C_nH_2n+2) wherein the carbon atoms are joined in a snake-like structure, branched (general formula C_nH_2n+2, n>3) wherein the carbon backbone splits off in one or more directions, or cyclic (general formula C_nH_2n, n>2) wherein the carbon backbone is linked so as to form a loop. According to the definition by IUPAC, the former two are alkanes, whereas the third group is called cycloalkanes.^[1] In other words, saturated hydrocarbons are divided into alkanes and cycloalkanes, depending on whether or not they have cyclic structures, and, in the technical sense, cycloalkanes are not alkanes. However, cycloalkanes are sometimes called cyclic alkanes, which can be confusing when "real" alkanes are called acyclic alkanes. Saturated hydrocarbons can also combine any of the linear, cyclic (e.g., polycyclic) and branching structures, and they are still alkanes (no general formula) as long as they are acyclic (i.e., having no loops). In organic chemistry, a cyclic organic compound is one in which a series of carbon atoms are connected together to form a loop or ring. ... IUPAC logo The International Union of Pure and Applied Chemistry (IUPAC) (Pronounced as eye-you-pack) is an international non-governmental organization established in 1919 devoted to the advancement of chemistry. ... cyclobutane Cycloalkanes (also called naphthenes) are chemical compounds with one or more carbon rings to which hydrogen atoms are attached according to the formula CnH2n. ... Acyclic can mean any of the following: In chemistry, an acyclic compound is a hydrocarbon compound having an open chain. ...

The simplest possible alkane (the parent molecule) is methane, CH₄. There is no limit to the number of carbon atoms that can be linked together, the only limitation being that the molecule is acyclic, is saturated, and is a hydrocarbon. Saturated oils and waxes are examples of larger alkanes where the number of carbons in the carbon backbone tends to be greater than 10. Methane is a chemical compound with the molecular formula . ... In chemistry, saturation has four different meanings: In physical chemistry, saturation is the point at which a solution of a substance can dissolve no more of that substance and additional amounts of that substance will appear as a precipitate. ... Look up Hydrocarbon in Wiktionary, the free dictionary. ... Oil painting is done on surfaces with pigment ground into a medium of oil - especially in early modern Europe, linseed oil. ... Wax has traditionally referred to a substance that is secreted by bees (beeswax) and used by them in constructing their honeycombs. ...

Alkanes are not very reactive and have little biological activity. Alkanes can be viewed as a molecular scaffold upon which can be hung the interesting biologically-active/reactive portions (functional groups) of the molecule. It has been suggested that this article or section be merged with Bioactivity. ... Scaffold may refer to: scaffolding as used in construction A gallows The Scaffold, UK musical group Scaffold - GNOME Development Environment Scaffold (Protein ECM) This is a disambiguation page â€” a navigational aid which lists pages that might otherwise share the same title. ... In ecology functional groups are collections of organisms based on morphological, physiological, behavioral, biochemical, or environmental responses or on trophic criteria. ...

Isomerism

Alkanes with more than three carbon atoms can be arranged in a multiple number of ways, forming different structural isomers. An isomer is like a chemical anagram, in which the atoms of a chemical compound are arranged or joined together in a different order to create different compounds with the same molecular formula. The simplest isomer of an alkane is the one in which the carbon atoms are arranged in a single chain with no branches. This isomer is sometimes called the n-isomer (n for "normal", although it is not necessarily the most common). However the chain of carbon atoms may also be branched at one or more points. The number of possible isomers increases rapidly with the number of carbon atoms (sequence A000602 in OEIS). For example: Image File history File links Download high-resolution version (1362x1600, 248 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Alkane Wikipedia:WikiProject Chemistry/Image Request ... Image File history File links Download high-resolution version (1362x1600, 248 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Alkane Wikipedia:WikiProject Chemistry/Image Request ... R-phrases S-phrases , , Flash point âˆ’60 Â°C Autoignition temperature 287 Â°C Explosive limits 1. ... Butane is an alkane hydrocarbon with the molecular formula C4H10. ... Cyclobutane, C4H8, with a molecular mass of 56. ... Methylcyclopropane Methylcyclopropane (C4H8) is the alkyl cycloalkane compound of methane and cyclopropane. ... Tetrahedrane is a hypothetical hydrocarbon with chemical formula C4H4 and a tetrahedral structure. ... In chemistry, isomers are molecules with the same chemical formula and often with the same kinds of bonds between atoms, but in which the atoms are arranged differently. ... For the game, see Anagrams. ... Look up chemical compound in Wiktionary, the free dictionary. ... The On-Line Encyclopedia of Integer Sequences (OEIS) is an extensive searchable database of integer sequences, freely available on the Web. ...

In addition to these isomers, the chain of carbon atoms may form one or more loops. Such compounds are called cycloalkanes. Methane is a chemical compound with the molecular formula . ... This article is about a chemical compound. ... Propane is a three-carbon alkane, normally a gas, but compressible to a liquid that is transportable. ... R-phrases S-phrases , , Flash point âˆ’60 Â°C Autoignition temperature 287 Â°C Explosive limits 1. ... Butane is an alkane hydrocarbon with the molecular formula C4H10. ... cyclobutane Cycloalkanes (also called naphthenes) are chemical compounds with one or more carbon rings to which hydrogen atoms are attached according to the formula CnH2n. ...

Nomenclature

The IUPAC nomenclature (systematic way of naming compounds) for alkanes is based on identifying hydrocarbon chains. Unbranched, saturated hydrocarbon chains are named systematically with a Greek numerical prefix denoting the number of carbons and the suffix "-ane".^[2] Organic nomenclature is the system established for naming and grouping organic compounds. ... The IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). ...

August Wilhelm von Hofmann suggested systematizing nomenclature by using the whole sequence of vowels a, e, i, o and u to create suffixes -ane, -ene, -ine (or -yne), -one, -une, for the hydrocarbons.^{[citation needed]} The first three name hydrocarbons with single, double and triple bonds; "-one" represents a ketone; "-ol" represents an alcohol or OH group; "-oxy-" means an ether and refers to oxygen between two carbons, so that methoxy-methane is the IUPAC name for dimethyl ether. August Wilhelm von Hofmann (April 8, 1818 _ May 5, 1892) was a German chemist. ... Ketone group A ketone (pronounced as key tone) is either the functional group characterized by a carbonyl group (O=C) linked to two other carbon atoms or a chemical compound that contains this functional group. ... This article is about a general class of chemical compounds. ...

It is difficult or impossible to find compounds with more than one IUPAC name. This is because shorter chains attached to longer chains are prefixes and the convention includes brackets. Numbers in the name, referring to which carbon a group is attached to, should be as low as possible, so that 1- is implied and usually omitted from names of organic compounds with only one side-group; "1-" is implied in Nitro-octane. Symmetric compounds will have two ways of arriving at the same name.

Linear alkanes

Straight-chain alkanes are sometimes indicated by the prefix n- (for normal) where a non-linear isomer exists. Although this is not strictly necessary, the usage is still common in cases where there is an important difference in properties between the straight-chain and branched-chain isomers, e.g., n-hexane or 2- or 3-methylpentane. In chemistry, isomers are molecules with the same chemical formula and often with the same kinds of chemical bonds between atoms, but in which the atoms are arranged differently (analogous to a chemical anagram). ... the 3rd ingredient in big mac ...

The first four members of the series (in terms of number of carbon atoms) are named as follows:

Alkanes with five or more carbon atoms are named by adding the suffix -ane to the appropriate Greek-language prefix numerical multiplier^[3] with elision of any terminal vowel (-a or -o) from the basic numerical term. Hence, pentane, C₅H₁₂; hexane, C₆H₁₄; heptane, C₇H₁₆; octane, C₈H₁₈; etc. For a more complete list, see List of alkanes. Methane is a chemical compound with the molecular formula . ... This article is about a chemical compound. ... Propane is a three-carbon alkane, normally a gas, but compressible to a liquid that is transportable. ... Butane, also called n-butane, is the unbranched alkane with four carbon atoms, CH3CH2CH2CH3. ... Look up affix in Wiktionary, the free dictionary. ... The numerical multiplier (or multiplying affix) in IUPAC nomenclature indicates how many particular atoms or functional groups are attached at a particular point in a molecule. ... Pentane (also known as amyl hydride or skellysolve) is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ... the 3rd ingredient in big mac ... R-phrases , , , , S-phrases , , , , , , , Flash point âˆ’4 Â°C Autoignition temperature 285 Â°C Explosive limits 1. ... For other uses, see Octane (disambiguation). ... The following is a list of alkanes and their common names, sorted by number of carbon atoms. ...

Branched alkanes

Simple branched alkanes often have a common name using a prefix to distinguish them from linear alkanes, for example n-pentane, isopentane, and neopentane. Image File history File links Download high-resolution version (1100x849, 153 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Alkane ... Image File history File links Download high-resolution version (1100x849, 153 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Alkane ... armchair conformational isomerism of Cyclohexane. ... Pentane also known as amyl hydride or skellysolve is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ... Pentane (also known as amyl hydride or skellysolve) is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ... Pentane also known as amyl hydride or skellysolve is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ... Pentane also known as amyl hydride or skellysolve is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ...

The key steps in the naming of more complicated branched alkanes are as follows:^[4]

Image File history File links This is a lossless scalable vector image. ... Image File history File links Size of this preview: 800 Ã— 496 pixelsFull resolution (1100 Ã— 682 pixel, file size: 19 KB, MIME type: image/png) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Size of this preview: 715 Ã— 600 pixelsFull resolution (800 Ã— 671 pixel, file size: 7 KB, MIME type: image/png) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

Cyclic alkanes

So-called cyclic alkanes are, in the technical sense, not alkanes, but cycloalkanes. They are hydrocarbons just like alkanes, but are containing one or more rings. cyclobutane Cycloalkanes (also called naphthenes) are chemical compounds with one or more carbon rings to which hydrogen atoms are attached according to the formula CnH2n. ...

Simple cycloalkanes have a prefix "cyclo-" to distinguish them from alkanes. Cycloalkanes are named as per their acyclic counterparts with respect to the number of carbon atoms, e.g., cyclopentane (C₅H₁₀) is a cycloalkane with 5 carbon atoms just like pentane (C₅H₁₂), but they are joined up in a five-membered ring. In a similar manner, propane and cyclopropane, butane and cyclobutane, etc. Cyclopentane is a highly flammable alicyclic hydrocarbon with chemical formula C5H10 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. ... Pentane (also known as amyl hydride or skellysolve) is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ... Propane is a three-carbon alkane, normally a gas, but compressible to a liquid that is transportable. ... Molecule structure formula of cyclopropane Cyclopropane is a cycloalkane molecule with the molecular formula C3H6 consisting of three carbon atoms linked to each other to form a ring, with each carbon atom bearing two hydrogen atoms. ... Butane, also called n-butane, is the unbranched alkane with four carbon atoms, CH3CH2CH2CH3. ... Cyclobutane, C4H8, with a molecular mass of 56. ...

Substituted cycloalkanes are named similar to substituted alkanes — the cycloalkane ring is stated, and the substituents are according to their position on the ring, with the numbering decided by Cahn-Ingold-Prelog rules.^[3] An example of the prioritisation of structure within the CIP system. ...

Trivial names

The trivial (non-systematic) name for alkanes is "paraffins." Together, alkanes are known as the paraffin series. Trivial names for compounds are usually historical artifacts. They were coined before the development of systematic names, and have been retained due to familiar usage in industry. Cycloalkanes are also called naphthenes. IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... For other uses, see Paraffin (disambiguation). ...

It is almost certain that the term paraffin stems from the petrochemical industry. Branched-chain alkanes are called isoparaffins. The use of the term "paraffin" is a general term and often does not distinguish between a pure compounds and mixtures of isomers with the same chemical formula (i.e., like a chemical anagram), e.g., pentane and isopentane. For other uses, see Paraffin (disambiguation). ... In chemistry, isomers are molecules with the same chemical formula and often with the same kinds of bonds between atoms, but in which the atoms are arranged differently. ... A chemical formula is an easy way of expressing information about the atoms that constitute a particular chemical compound. ... For the game, see Anagrams. ... Pentane (also known as amyl hydride or skellysolve) is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ... Pentane also known as amyl hydride or skellysolve is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ...

Butane is an alkane hydrocarbon with the molecular formula C4H10. ... Pentane also known as amyl hydride or skellysolve is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ... Pentane also known as amyl hydride or skellysolve is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ...

Occurrence

Occurrence of alkanes in the Universe

Alkanes form a significant portion of the atmospheres of the outer gas planets such as Jupiter (0.1% methane, 0.0002% ethane), Saturn (0.2% methane, 0.0005% ethane), Uranus (1.99% methane, 0.00025% ethane) and Neptune (1.5% methane, 1.5 ppm ethane). Titan (1.6% methane), a satellite of Saturn, was examined by the Huygens probe, which indicate that Titan's atmosphere periodically rains liquid methane onto the moon's surface.^[5] Also on Titan, a methane-spewing volcano was spotted and this volcanism is believed to be a significant source of the methane in the atmosphere. There also appear to be Methane/Ethane lakes near the north polar regions of Titan, as discovered by Cassini's radar imaging. Methane and ethane have also been detected in the tail of the comet Hyakutake. Chemical analysis showed that the abundances of ethane and methane were roughly equal, which is thought to imply that its ices formed in interstellar space, away from the Sun, which would have evaporated these volatile molecules.^[6] Alkanes have also been detected in meteorites such as carbonaceous chondrites. Download high resolution version (840x840, 41 KB) Original Caption Released with Image: This processed color image of Jupiter was produced in 1990 by the U.S. Geological Survey from a Voyager image captured in 1979. ... Download high resolution version (840x840, 41 KB) Original Caption Released with Image: This processed color image of Jupiter was produced in 1990 by the U.S. Geological Survey from a Voyager image captured in 1979. ... Atmosphere is the general name for a layer of gases that may surround a material body of sufficient mass. ... For other uses, see Jupiter (disambiguation). ... This article is about the planet. ... For other uses, see Uranus (disambiguation). ... For other uses, see Neptune (disambiguation). ... Titan (, from Ancient Greek Î¤á¿‘Ï„Î¬Î½) or Saturn VI is the largest moon of Saturn and the only moon known to have a dense atmosphere. ... Methane is a chemical compound with the molecular formula . ... This article is about a chemical compound. ... Hyakutake picture from March 1996 Comet Hyakutake (formally C/1996 B2) was discovered by Yuji Hyakutake on January 30, 1996. ... Willamette Meteorite A meteorite is a natural object originating in outer space that survives an impact with the Earths surface without being destroyed. ... Some carbonaceous chondrites. ...

Occurrence of alkanes on Earth

Traces of methane gas (about 0.0001% or 1 ppm) occur in the Earth's atmosphere, produced primarily by organisms such as Archaea, found for example in the gut of cows.^{[citation needed]} Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (pronounced ) are a group of prokaryotic and single-celled microorganisms. ...

The most important commercial sources for alkanes are natural gas and oil.^[7] Natural gas contains primarily methane and ethane, with some propane and butane: oil is a mixture of liquid alkanes and other hydrocarbons. These hydrocarbons were formed when dead marine animals and plants (zooplankton and phytoplankton) died and sank to the bottom of ancient seas and were covered with sediments in an anoxic environment and converted over many millions of years at high temperatures and high pressure to their current form. Natural gas resulted thereby for example from the following reaction: Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ... For other uses, see Natural gas (disambiguation). ... Petro redirects here. ... Propane is a three-carbon alkane, normally a gas, but compressible to a liquid that is transportable. ... Butane, also called n-butane, is the unbranched alkane with four carbon atoms, CH3CH2CH2CH3. ... In chemistry, a hydrocarbon is a cleaning solution consisting only of carbon (C) and hydrogen (H). ...

These hydrocarbons collected in porous rocks, located beneath an impermeable cap rock and so are trapped. Unlike methane, which is constantly reformed in large quantities, higher alkanes (alkanes with 9 or more carbon atoms) rarely develop to a considerable extent in nature.^{[citation needed]} These deposits, e.g., oil fields, have formed over millions of years and once exhausted cannot be readily replaced. The depletion of these hydrocarbons is the basis for what is known as the energy crisis. Drilling rig in a small oil field Near Sarnia, Ontario, 2001 An oil field is an area with an abundance of oil wells extracting petroleum (oil) from below ground. ... This article is about energy crises in general. ...

Solid alkanes are known as tars and are formed when more volatile alkanes such as gases and oil evaporate from hydrocarbon deposits. One of the largest natural deposits of solid alkanes is in the asphalt lake known as the Pitch Lake in Trinidad and Tobago. Tar can be produced from corn stalks by heating in a microwave. ... Vaporization redirects here. ... The term asphalt is often used as an abbreviation for asphalt concrete. ... The Pitch Lake The Pitch Lake is a lake of natural asphalt located at La Brea in southwest Trinidad. ...

Methane is also present in what is called biogas, produced by animals and decaying matter, which is a possible renewable energy source. Biogas-bus in Bern, Switzerland Biogas typically refers to a (biofuel) gas produced by the anaerobic digestion or fermentation of organic matter including manure, sewage sludge, municipal solid waste, biodegradable waste or any other biodegradable feedstock, under anaerobic conditions. ... Renewable energy (sources) or RES includes all sources of energy that are captured from on-going natural processes, such as solar power, wind power, water flow in streams (hydro power), biomass, biodiesel and geothermal heat flows. ...

Alkanes have a low solubility in water, so the content in the oceans is negligible; however, at high pressures and low temperatures (such as at the bottom of the oceans), methane can co-crystallize with water to form a solid methane hydrate.^{[citation needed]} Although this cannot be commercially exploited at the present time, the amount of combustible energy of the known methane hydrate fields exceeds the energy content of all the natural gas and oil deposits put together^{[citation needed]};methane extracted from methane hydrate is considered therefore a candidate for future fuels. Burning ice. Methane released by heating burns, water drips. ...

Biological occurrence

Although alkanes occur in nature in various way, they do not rank biologically among the essential materials. Cycloalkanes with 14 to 18 carbon atoms occur in musk, extracted from deer of the family Moschidae.^{[citation needed]} All further information refers to (acyclic) alkanes. Moschus moschiferus, Siberian musk deer Musk is the name originally given to a substance with a penetrating odor obtained from a gland of the male musk deer, which is situated between its stomach and genitals. ... This article is about the ruminent animal. ... The four species of musk deer make up the family Moschidae. ...

Certain types of bacteria can metabolise alkanes: they prefer even-numbered carbon chains as they are easier to degrade than odd-numbered chains.^{[citation needed]} Image File history File links Download high resolution version (1280x900, 712 KB) Beschreibung: Rotbuntes Rind Fotograf: Darkone, 2. ... Image File history File links Download high resolution version (1280x900, 712 KB) Beschreibung: Rotbuntes Rind Fotograf: Darkone, 2. ... Methanogens are archaea that produce methane as a metabolic byproduct in anoxic conditions. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (pronounced ) are a group of prokaryotic and single-celled microorganisms. ... Methane is a chemical compound with the molecular formula . ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ...

On the other hand, certain archaea, the methanogens, produce large quantities of methane by the metabolism of carbon dioxide or other oxidised organic compounds. The energy is released by the oxidation of hydrogen: Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (pronounced ) are a group of prokaryotic and single-celled microorganisms. ... Methanogens are archaea that produce methane as a metabolic byproduct in anoxic conditions. ... Methane is a chemical compound with the molecular formula . ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... The most fundamental reactions in chemistry are the redox processes. ... This article is about the chemistry of hydrogen. ...

Methanogens are also the producers of marsh gas in wetlands, and release about two billion tonnes of methane per year^{[citation needed]} — the atmospheric content of this gas is produced nearly exclusively by them. The methane output of cattle and other herbivores, which can release up to 150 litres per day,^{[citation needed]} and of termites,^{[citation needed]} is also due to methanogens. They also produce this simplest of all alkanes in the intestines of humans. Methanogenic archaea are, hence, at the end of the carbon cycle, with carbon being released back into the atmosphere after having been fixed by photosynthesis. It is probable that our current deposits of natural gas were formed in a similar way.^{[citation needed]} Natural gas rig Natural gas is a gas produced by the anaerobic decay of organic material. ... A subtropical wetland in Florida, USA, with an endangered American Crocodile. ... For general information about the genus, including other species of cattle, see Bos. ... A deer and two fawns feeding on some foliage A herbivore is often defined as any organism that eats only plants[1]. By that definition, many fungi, some bacteria, many animals, about 1% of flowering plants and some protists can be considered herbivores. ... Families Mastotermitidae Kalotermitidae Termopsidae Hodotermitidae Rhinotermitidae Serritermitidae Termitidae Termites, sometimes known as white ants, are a group of social insects usually classified at the taxonomic rank of order Isoptera. ... In anatomy, the intestine is the segment of the alimentary canal extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine. ... For the thermonuclear reaction involving carbon that helps power stars, see CNO cycle. ... Photosynthesis splits water to liberate O2 and fixes CO2 into sugar The leaf is the primary site of photosynthesis in plants. ... For other uses, see Natural gas (disambiguation). ...

Alkanes also play a role, if a minor role, in the biology of the three eukaryotic groups of organisms: fungi, plants and animals. Some specialised yeasts, e.g., Candida tropicale, Pichia sp., Rhodotorula sp., can use alkanes as a source of carbon and/or energy. The fungus Amorphotheca resinae prefers the longer-chain alkanes in aviation fuel, and can cause serious problems for aircraft in tropical regions.^{[citation needed]} In 1992, apple growers in Washington harvested about 805,000 boxes of Fujis. ... In 1992, apple growers in Washington harvested about 805,000 boxes of Fujis. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... For the fictional character, see Fungus the Bogeyman. ... Species P. pastoris Synonyms Hansenula Pichia is a genus of teleomorphic yeasts in the family Saccharomycetaceae. ... Please wikify (format) this article or section as suggested in the Guide to layout and the Manual of Style. ... An aviation fuel truck. ...

In plants, it is the solid long-chain alkanes that are found; they form a firm layer of wax, the cuticle, over areas of the plant exposed to the air. This protects the plant against water loss, while preventing the leaching of important minerals by the rain. It is also a protection against bacteria, fungi, and harmful insects — the latter sink with their legs into the soft waxlike substance and have difficulty moving. The shining layer on fruits such as apples consists of long-chain alkanes. The carbon chains are usually between twenty and thirty carbon atoms in length and are made by the plants from fatty acids. The exact composition of the layer of wax is not only species-dependent, but changes also with the season and such environmental factors as lighting conditions, temperature or humidity. Plant cuticles are a protective waxy covering produced only by the epidermal cells (Kolattukudy, 1996) of leaves, young shoots and all other aerial plant organs. ... Leaching may refer to: Leaching (agriculture) Leaching (chemical science) Leaching (metallurgy) Dump leaching Heap leaching Tank leaching Leaching (pedology) Bioleaching Parboiling, also known as leaching Categories: ... Not to be confused with fats. ...

Alkanes are found in animal products, although they are less important than unsaturated hydrocarbons. One example is the shark liver oil, which is approximately 14% pristane (2,6,10,14-tetramethylpentadecane, C₁₉H₄₀).^{[citation needed]} Their occurrence is more important in pheromones, chemical messenger materials, on which above all insects are dependent for communication. With some kinds, as the support beetle Xylotrechus colonus, primarily pentacosane (C₂₅H₅₂), 3-methylpentaicosane (C₂₆H₅₄) and 9-methylpentaicosane (C₂₆H₅₄), they are transferred by body contact. With others like the tsetse fly Glossina morsitans morsitans, the pheromone contains the four alkanes 2-methylheptadecane (C₁₈H₃₈), 17,21-dimethylheptatriacontane (C₃₉H₈₀), 15,19-dimethylheptatriacontane (C₃₉H₈₀) and 15,19,23-trimethylheptatriacontane (C₄₀H₈₂), and acts by smell over longer distances, a useful characteristic for pest control.^{[citation needed]} Pristane is a natural saturated terpenoid alkane obtained primarily from shark liver oil. ... Fanning honeybee exposes Nasonov gland (white-at tip of abdomen) releasing pheromone to entice swarm into an empty hive A pheromone (from Greek Ï†ÎÏÏ‰ phero to bear + â€˜Î¿ÏÎ¼ÏŒÎ½Î· hormone) is a chemical that triggers a natural behavioral response in another member of the same species. ... Pentacosane is an alkane hydrocarbon with the structural formula CH3(CH2)23CH3. ... Binomial name Glossina morsitans The tsetse fly, Glossina morsitans, is a fly (order Diptera) that eats blood from animals, including humans. ... A crop duster applies low-insecticide bait that is targeted against Western corn rootworms Pest control refers to the regulation or management of another species defined as a pest, usually because it is believed to be detrimental to a persons health, the ecology or the economy Pest control is...

Ecological relations

One example, in which both plant and animal alkanes play a role, is the ecological relationship between the sand bee (Andrena nigroaenea) and the early spider orchid (Ophrys sphegodes); the latter is dependent for pollination on the former. Sand bees use pheromones in order to identify a mate; in the case of A. nigroaenea, the females emit a mixture of tricosane (C₂₃H₄₈), pentacosane (C₂₅H₅₂) and heptacosane (C₂₇H₅₆) in the ratio 3:3:1, and males are attracted by specifically this odour. The orchid takes advantage of this mating arrangement to get the male bee to collect and disseminate its pollen; parts of its flower not only resemble the appearance of sand bees, but also produce large quantities of the three alkanes in the same ratio as female sand bees. As a result numerous males are lured to the blooms and attempt to copulate with their imaginary partner: although this endeavour is not crowned with success for the bee, it allows the orchid to transfer its pollen, which will be dispersed after the departure of the frustrated male to different blooms. Image File history File links Download high resolution version (685x795, 140 KB) Description: Ophrys sphegodes, flower Picture taken by BerndH Date: 23. ... Image File history File links Download high resolution version (685x795, 140 KB) Description: Ophrys sphegodes, flower Picture taken by BerndH Date: 23. ... Binomial name Ophrys sphegodes Mill. ... Binomial name Mill. ... Carpenter bee with pollen collected from Night-blooming cereus Pollination is an important step in the reproduction of seed plants: the transfer of pollen grains (containing the male gametes, sperm) to the plant carpel of flowering plants, the structure that contains the ovule (which in turn houses the female gamete... Tricosane is an alkane hydrocarbon with the chemical formula CH3(CH2)21CH3. ... Pentacosane is an alkane hydrocarbon with the structural formula CH3(CH2)23CH3. ... Heptacosane is an alkane hydrocarbon with the structural formula CH3(CH2)25CH3. ...

Production

Petroleum refining

As stated earlier, the most important source of alkanes is natural gas and crude oil.^[7] Alkanes are separated in an oil refinery by fractional distillation and processed into many different products Image File history File links ShellMartinez-refi. ... Image File history File links ShellMartinez-refi. ... View of Shell Oil Refinery in Martinez, California. ... Martinez is the name of several places in the United States of America: Martinez, California Martinez, Georgia Martinez, New Mexico Martinez, Texas Martinez, Connecticut Martinez is also surname of several people: Angie Martinez - Puerto Rican musician Conchita Martinez - Spanish tennis player Eduardo Cardinal MartÃnez Somalo - high official in the... This article is about the U.S. state. ... For other uses, see Natural gas (disambiguation). ... Pumpjack pumping an oil well near Sarnia, Ontario Petroleum (from Greek petra â€“ rock and elaion â€“ oil or Latin oleum â€“ oil ) or crude oil is a thick, dark brown or greenish liquid. ... View of Shell Oil Refinery in Martinez, California. ... Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. ...

Fischer-Tropsch

The Fischer-Tropsch process is a method to synthesize liquid hydrocarbons, including alkanes, from carbon monoxide and hydrogen. This method is used to produce substitutes for petroleum distillates. // The Fischer-Tropsch process is a catalyzed chemical reaction in which carbon monoxide and hydrogen are converted into liquid hydrocarbons of various forms. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ...

Laboratory preparation

There is usually little need for alkanes to be synthesized in the laboratory, since they are usually commercially available. Also, alkanes are generally non-reactive chemically or biologically, and do not undergo functional group interconversions cleanly. When alkanes are produced in the laboratory, it is often a side-product of a reaction. For example, the use of n-butyllithium as a strong base gives the conjugate acid, n-butane as a side-product: An organolithium reagent is a carbon nucleophile similar to a Grignard reagent. ... Acids and bases: Acid-base extraction Acid-base reaction Acid dissociation constant Acidity function Buffer solutions pH Proton affinity Self-ionization of water Acids: Lewis acids Mineral acids Organic acids Strong acids Superacids Weak acids Bases: Lewis bases Organic bases Strong bases Superbases Non-nucleophilic bases Weak bases edit In...

However, at times it may be desirable to make a portion of a molecule into an alkane like functionality (alkyl group) using the above or similar methods. For example, an ethyl group is an alkyl group; when this is attached to a hydroxy group, it gives ethanol, which is not an alkane. To do so, the best-known methods are hydrogenation of alkenes: Lithium hydroxide (LiOH) is a corrosive alkali. ... An alkyl is a univalent radical containing only carbon and hydrogen atoms arranged in a chain. ... In chemistry, an ethyl group is an alkyl functional group derived from ethane (C2H6). ... This prefix in chemical nomenclature indicates the presence of a hydroxyl functional group (-OH). ... Grain alcohol redirects here. ... Hydrogenation is a class of chemical reactions which result an addition of hydrogen (H2) usually to unsaturated organic compounds. ... This article is about the chemical compound. ...

Alkanes or alkyl groups can also be prepared directly from alkyl halides in the Corey-House-Posner-Whitesides reaction. The Barton-McCombie deoxygenation^[8]^[9] removes hydroxyl groups from alcohols e.g. An alkyl is a univalent radical containing only carbon and hydrogen atoms arranged in a chain. ... In chemistry, an alkyl halide is an organic molecule of the form R_X, where X is a halide and R contains a carbon atom bonded to other functional groups or hydrogens. ... The Corey-Posner-Whitesides-House reaction was developed by the co-operation of four organic chemists: E.J. Corey of Harvard University, G.H. Posner of the Johns Hopkins University, G.M. Whitesides of MIT and H.O. House of the Georgia Institute of Technology. ... The Barton-McCombie deoxygenation is a organic reaction in which an hydroxy functional group in an organic compound is replaced by a proton to an alkane . ...

and the Clemmensen reduction^[10]^[11]^[12]^[13] removes carbonyl groups from aldehydes and ketones to form alkanes or alkyl-substituted compounds e.g.: Image File history File links Download high-resolution version (1391x276, 3 KB) Description: Reaction scheme of the Barton-McCombie deoxygenation. ... The Clemmensen reduction is a chemical reaction aimed at reducing carbonyl groups of aldehydes and ketones to -CH2- groups. ...

Applications

The applications of a certain alkane can be determined quite well according to the number of carbon atoms. The first four alkanes are used mainly for heating and cooking purposes, and in some countries for electricity generation. Methane and ethane are the main components of natural gas; they are normally stored as gases under pressure. It is, however, easier to transport them as liquids: This requires both compression and cooling of the gas. Methane is a chemical compound with the molecular formula . ... This article is about a chemical compound. ...

Propane and butane can be liquefied at fairly low pressures, and are well known as liquified petroleum gas (LPG). Propane, for example, is used in the propane gas burner, butane in disposable cigarette lighters. The two alkanes are used as propellants in aerosol sprays. Propane is a three-carbon alkane, normally a gas, but compressible to a liquid that is transportable. ... Butane, also called n-butane, is the unbranched alkane with four carbon atoms, CH3CH2CH2CH3. ... 45 kg LPG cylinders Spherical Gas Container typically found in Refineries. ... Aerosol spray can Aerosol spray is a type of canister that sprays an aerosol when its button is pressed or held down. ...

From pentane to octane the alkanes are reasonably volatile liquids. They are used as fuels in internal combustion engines, as they vaporise easily on entry into the combustion chamber without forming droplets, which would impair the uniformity of the combustion. Branched-chain alkanes are preferred, as they are much less prone to premature ignition, which causes knocking than their straight-chain homologue. This propensity to premature ignition is measured by the octane rating of the fuel, where 2,2,4-trimethylpentane (isooctane) has an arbitrary value of 100, and heptane has a value of zero. Apart from their use as fuels, the middle alkanes are also good solvents for nonpolar substances. Pentane (also known as amyl hydride or skellysolve) is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ... For other uses, see Octane (disambiguation). ... A colorized automobile engine The internal combustion engine is an engine in which the combustion of fuel and an oxidizer (typically air) occurs in a confined space called a combustion chamber. ... Knocking (also called pinking or pinging)â€” colloquially detonationâ€”in internal combustion engines occurs when air/fuel mixture in the cylinder detonates or ignites prior to the timed pre-set conditions in the engines cylinder(s). ... A gas station pump offering five different octane ratings. ... R-phrases , , , , S-phrases , , , , , , , Flash point 4. ... R-phrases , , , , S-phrases , , , , , , , Flash point âˆ’4 Â°C Autoignition temperature 285 Â°C Explosive limits 1. ... For other uses, see Solvent (disambiguation). ...

Alkanes from nonane to, for instance, hexadecane (an alkane with sixteen carbon atoms) are liquids of higher viscosity, less and less suitable for use in gasoline. They form instead the major part of diesel and aviation fuel. Diesel fuels are characterised by their cetane number, cetane being an old name for hexadecane. However, the higher melting points of these alkanes can cause problems at low temperatures and in polar regions, where the fuel becomes too thick to flow correctly. Nonane is an alkane hydrocarbon with the chemical formula CH3(CH2)7CH3. ... Hexadecane, also called cetane, is an alkane hydrocarbon with the chemical formula CH3(CH2)14CH3. ... For other uses, see Viscosity (disambiguation). ... This article is about the fuel. ... An aviation fuel truck. ... Cetane number or CN is to diesel fuel what octane rating is to gasoline. ...

Alkanes from hexadecane upwards form the most important components of fuel oil and lubricating oil. In latter function, they work at the same time as anti-corrosive agents, as their hydrophobic nature means that water cannot reach the metal surface. Many solid alkanes find use as paraffin wax, for example, in candles. This should not be confused however with true wax, which consists primarily of esters. An oil tanker taking on bunker fuel. ... Mineral oil or liquid petrolatum is a by-product in the distillation of petroleum to produce gasoline. ... Paraffin is a common name for a group of high molecular weight alkane hydrocarbons with the general formula CnH2n+2, where n is greater than about 20. ... For other uses, see Candle (disambiguation). ... candle wax This page is about the substance. ... For other uses, see Ester (disambiguation). ...

Alkanes with a chain length of approximately 35 or more carbon atoms are found in bitumen, used, for example, in road surfacing. However, the higher alkanes have little value and are usually split into lower alkanes by cracking. Ewer from Iran, dated 1180-1210CE. Composed of brass worked in repoussÃ© and inlaid with silver and bitumen. ... Factory of Shukhov cracking process, Baku, USSR, 1934 In petroleum geology and chemistry, cracking is the process whereby complex organic molecules such as kerogens or heavy hydrocarbons are broken down into simpler molecules (e. ...

Some synthetic polymers such as polyethylene and polypropylene are alkanes with chains containing hundreds of thousands of carbon atoms. These materials are used in innumerable applications, and billions of kilograms of these materials are made and used each year. A polymer is a long, repeating chain of atoms, formed through the linkage of many molecules called monomers. ... This article does not cite any references or sources. ... Polypropylene lid of a Tic Tacs box, with a living hinge and the resin identification code under its flap Micrograph of polypropylene Polypropylene or polypropene (PP) is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including food packaging, ropes, textiles, stationery, plastic...

Physical properties

Boiling point

Alkanes experience inter-molecular van der Waals forces. Stronger inter-molecular van der Waals forces give rise to greater boiling points of alkanes.^[7] Image File history File links Alkanschmelzundsiedepunkt. ... Image File history File links Alkanschmelzundsiedepunkt. ... In chemistry, the term van der Waals force originally referred to all forms of intermolecular forces; however, in modern usage it tends to refer to intermolecular forces that deal with forces due to the polarization of molecules. ...

Under standard conditions, from CH₄ to C₄H₁₀ alkanes are gaseous; from C₅H₁₂ to C₁₇H₃₆ they are liquids; and after C₁₈H₃₈ they are solids. As the boiling point of alkanes is primarily determined by weight, it should not be a surprise that the boiling point has almost a linear relationship with the size (molecular weight) of the molecule. As a rule of thumb, the boiling point rises 20 - 30 °C for each carbon added to the chain; this rule applies to other homologous series.^[7] Temperature and air pressure can vary from one place to another on the Earth, and can also vary in the same place with time. ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ...

A straight-chain alkane will have a boiling point higher than a branched-chain alkane due to the greater surface area in contact, thus the greater van der Waals forces, between adjacent molecules. For example, compare isobutane and n-butane, which boil at -12 and 0 °C, and 2,2-dimethylbutane and 2,3-dimethylbutane which boil at 50 and 58 °C, respectively.^[7] For the latter case, two molecules 2,3-dimethylbutane can "lock" into each other better than the cross-shaped 2,2-dimethylbutane, hence the greater van der Waals forces. Butane is an alkane hydrocarbon with the molecular formula C4H10. ... R-phrases S-phrases , , Flash point âˆ’60 Â°C Autoignition temperature 287 Â°C Explosive limits 1. ...

On the other hand, cycloalkanes tend to have higher boiling points than their linear counterparts due to the locked conformations of the molecules, which give a plane of intermolecular contact.^{[citation needed]}

Melting point

The melting points of the alkanes follow a similar trend to boiling points for the same reason as outlined above. That is, (all other things being equal) the larger the molecule the higher the melting point. There is one significant difference between boiling points and melting points. Solids have more ridged and fixed structure than liquids. This rigid structure requires energy to break down. Thus the stronger better put together solid structures will require more energy to break apart. For alkanes, this can be seen from the graph above (i.e., the blue line). The odd-numbered alkanes have a lower trend in melting points that even numbered alkanes. This is because even numbered alkanes pack well in the solid phase, forming a well-organised structure, which requires more energy to break apart. The odd-number alkanes pack less well and so the "looser" organised solid packing structure requires less energy to break apart.^[14] The melting point of a solid is the temperature range at which it changes state from solid to liquid. ... Alternate use: Boiling Point, English title of Kitano Takeshis film 3-4X Jūgatsu; Boiling Point (TV series) The boiling point of a substance is the temperature at which it can change state from a liquid to a gas throughout the bulk of the liquid. ...

The melting points of branched-chain alkanes can be either higher or lower than those of the corresponding straight-chain alkanes, again depending on the ability of the alkane in question to packing well in the solid phase: This is particularly true for isoalkanes (2-methyl isomers), which often have melting points higher than those of the linear analogues.

Conductivity

Alkanes do not conduct electricity, nor are they substantially polarized by an electric field. For this reason they do not form hydrogen bonds and are insoluble in polar solvents such as water. Since the hydrogen bonds between individual water molecules are aligned away from an alkane molecule, the coexistence of an alkane and water leads to an increase in molecular order (a reduction in entropy). As there is no significant bonding between water molecules and alkane molecules, the second law of thermodynamics suggests that this reduction in entropy should be minimised by minimising the contact between alkane and water: Alkanes are said to be hydrophobic in that they repel water. Electricity (from New Latin Ä“lectricus, amberlike) is a general term for a variety of phenomena resulting from the presence and flow of electric charge. ... In electrodynamics, polarization (also spelled polarisation) is the property of electromagnetic waves, such as light, that describes the direction of their transverse electric field. ... In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. ... An example of a quadruple hydrogen bond between a self-assembled dimer complex reported by Meijer and coworkers. ... For other uses, see: information entropy (in information theory) and entropy (disambiguation). ... The second law of thermodynamics is an expression of the universal law of increasing entropy. ... In chemistry, hydrophobic or lipophilic species, or hydrophobes, tend to be electrically neutral and nonpolar, and thus prefer other neutral and nonpolar solvents or molecular environments. ...

Their solubility in nonpolar solvents is relatively good, a property that is called lipophilicity. Different alkanes are, for example, miscible in all proportions among themselves. ...

The density of the alkanes usually increases with increasing number of carbon atoms, but remains less than that of water. Hence, alkanes form the upper layer in an alkane-water mixture.

Molecular geometry

The molecular structure of the alkanes directly affects their physical and chemical characteristics. It is derived from the electron configuration of carbon, which has four valence electrons. The carbon atoms in alkanes are always sp³ hybridised, that is to say that the valence electrons are said to be in four equivalent orbitals derived from the combination of the 2s orbital and the three 2p orbitals. These orbitals, which have identical energies, are arranged spatially in the form of a tetrahedron, the angle of cos⁻¹(−⅓) ≈ 109.47° between them. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Methane is a chemical compound with the molecular formula . ... Electron atomic and molecular orbitals In atomic physics and quantum chemistry, the electron configuration is the arrangement of electrons in an atom, molecule, or other physical structure (, a crystal). ... For other uses, see Carbon (disambiguation). ... In chemistry, valence electrons are the electrons contained in the outermost, or valence, electron shell of an atom. ... Four sp3 orbitals. ...

Bond lengths and bond angles

An alkane molecule has only C – H and C – C single bonds. The former result from the overlap of a sp³-orbital of carbon with the 1s-orbital of a hydrogen; the latter by the overlap of two sp³-orbitals on different carbon atoms. The bond lengths amount to 1.09×10⁻¹⁰ m for a C – H bond and 1.54×10⁻¹⁰ m for a C – C bond. In molecular geometry, bond length or bond distance is the distance between two bonded atoms in a molecule. ...

The spatial arrangement of the bonds is similar to that of the four sp³-orbitals — they are tetrahedrally arranged, with an angle of 109.47° between them. Structural formulae that represent the bonds as being at right angles to one another, while both common and useful, do not correspond with the reality. My feeble attempt at drawing methane in terms of structure File links The following pages link to this file: Orbital hybridisation Categories: GFDL images ... My feeble attempt at drawing methane in terms of structure File links The following pages link to this file: Orbital hybridisation Categories: GFDL images ...

Conformation

The structural formula and the bond angles are not usually sufficient to completely describe the geometry of a molecule. There is a further degree of freedom for each carbon – carbon bond: the torsion angle between the atoms or groups bound to the atoms at each end of the bond. The spatial arrangement described by the torsion angles of the molecule is known as its conformation. Alkane stereochemistry concerns the stereochemistry of linear alkanes and the linear alkane conformers. ... Geometry of the water molecule Molecules have fixed equilibrium geometries--bond lengths and angles--that are dictated by the laws of quantum mechanics. ... Degrees of freedom is a general term used in explaining dependence on parameters, and implying the possibility of counting the number of those parameters. ... A torsion angle, better referred to as a dihedral angle, is formed by three consecutive bonds in a molecule and defined by the angle created by the projection of the two outer bonds on a plane that is perpendicular to the central bond. ... Conformation generally means structural arrangement. ...

Ethane forms the simplest case for studying the conformation of alkanes, as there is only one C – C bond. If one looks down the axis of the C – C bond, one will see the so-called Newman projection. The hydrogen atoms on both the front and rear carbon atoms have an angle of 120° between them, resulting from the projection of the base of the tetrahedron onto a flat plane. However, the torsion angle between a given hydrogen atom attached to the front carbon and a given hydrogen atom attached to the rear carbon can vary freely between 0° and 360°. This is a consequence of the free rotation about a carbon – carbon single bond. Despite this apparent freedom, only two limiting conformations are important: eclipsed conformation and staggered conformation. Image File history File links Newman_projection_ethane. ... Image File history File links Newman_projection_ethane. ... Image File history File links Size of this preview: 800 Ã— 404 pixelsFull resolution (1100 Ã— 555 pixel, file size: 128 KB, MIME type: image/png) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Size of this preview: 800 Ã— 404 pixelsFull resolution (1100 Ã— 555 pixel, file size: 128 KB, MIME type: image/png) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... armchair conformational isomerism of Cyclohexane. ... This article is about a chemical compound. ... In chemistry, a chemical conformation is the spatial arrangement of atoms in a molecule. ... In chemistry an eclipsed conformation is a chemical conformation that exists in any open chain single chemical bond connecting two sp3 hybridised atoms as a conformational energy maximum due to steric hindrance. ... In chemistry a staggered conformation is a chemical conformation that exists in any open chain single chemical bond connecting two sp3 hybridised atoms as a conformational energy minimum. ...

The two conformations, also known as rotamers, differ in energy: The staggered conformation is 12.6 kJ/mol lower in energy (more stable) than the eclipsed conformation (the least stable). In chemistry, a chemical conformation is the spatial arrangement of atoms in a molecule. ...

This difference in energy between the two conformations, known as the torsion energy, is low compared to the thermal energy of an ethane molecule at ambient temperature. There is constant rotation about the C-C bond. The time taken for an ethane molecule to pass from one staggered conformation to the next, equivalent to the rotation of one CH₃-group by 120° relative to the other, is of the order of 10⁻¹¹ seconds. Alkane stereochemistry concerns the stereochemistry of linear alkanes and the linear alkane conformers. ...

The case of higher alkanes is more complex but based on similar principles, with the antiperiplanar conformation always being the most favoured around each carbon-carbon bond. For this reason, alkanes are usually shown in a zigzag arrangement in diagrams or in models. The actual structure will always differ somewhat from these idealised forms, as the differences in energy between the conformations are small compared to the thermal energy of the molecules: Alkane molecules have no fixed structural form, whatever the models may suggest.

Spectroscopic properties

Virtually all organic compounds contain carbon – carbon and carbon – hydrogen bonds, and so show some of the features of alkanes in their spectra. Alkanes are notable for having no other groups, and therefore for the absence of other characteristic spectroscopic features.

Infrared spectroscopy

The carbon – hydrogen stretching mode gives a strong absorption between 2850 and 2960 nanometres, while the carbon – carbon stretching mode absorbs between 800 and 1300 nm. The carbon – hydrogen bending modes depend on the nature of the group: methyl groups show bands at 1450 nm and 1375 nm, while methylene groups show bands at 1465 nm and 1450 nm. Carbon chains with more than four carbon atoms show a weak absorption at around 725 nm.

NMR spectroscopy

The proton resonances of alkanes are usually found at δ_H = 0.5 – 1.5. The carbon-13 resonances depend on the number of hydrogen atoms attached to the carbon: δ_C = 8 – 30 (primary, methyl, -CH₃), 15 – 55 (secondary, methylene, -CH₂-), 20 – 60 (tertiary, methyne, C-H) and quaternary. The carbon-13 resonance of quaternary carbon atoms is characteristically weak, due to the lack of Nuclear Overhauser effect and the long relaxation time, and can be missed in weak samples, or sample that have not been run for a sufficiently long time. In nuclear magnetic resonance (NMR), the chemical shift describes the dependence of nuclear magnetic energy levels on the electronic environment in a molecule. ... It has been suggested that this article or section be merged with Dynamic nuclear polarisation. ... Relaxation time is a general physics concept for the characteristic time in which a system relaxes under certain changes in external conditions. ...

Mass spectrometry

Alkanes have a high ionisation energy, and the molecular ion is usually weak. The fragmentation pattern can be difficult to interpret, but, in the case of branched chain alkanes, the carbon chain is preferentially cleaved at tertiary or quaternary carbons due to the relative stability of the resulting free radicals. The fragment resulting from the loss of a single methyl group (M−15) is often absent, and other fragment are often spaced by intervals of fourteen mass units, corresponding to sequential loss of CH₂-groups. ionisation energy is the energy required to remove the most loosely held electron from one mole of gaseous atoms to produce 1 mole of gaseous ions each with a charge of 1+. ... In chemistry free radicals are uncharged atomic or molecular species with unpaired electrons or an otherwise open shell configuration. ...

Chemical properties

In general, alkanes show a relatively low reactivity, because their C bonds are relatively stable and cannot be easily broken. Unlike most other organic compounds, they possess no functional groups. In organic chemistry, functional groups (or moieties) are specific groups of atoms within molecules, that are responsible for the characteristic chemical reactions of those molecules. ...

They react only very poorly with ionic or other polar substances. The acid dissociation constant (pK_a) values of all alkanes are above 60, hence they are practically inert to acids and bases (see: carbon acids). This inertness is the source of the term paraffins (with the meaning here of "lacking affinity"). In crude oil the alkane molecules have remained chemically unchanged for millions of years. An acid dissociation constant, denoted by Ka, is an equilibrium constant for the dissociation of a weak acid. ... A carbanion is an anion in which carbon has an unshared pair of electrons and bears a negative charge usually with three substituents for a total of eight valence electrons [1]. The carbanion exists in a trigonal pyramidal geometry. ... Pumpjack pumping an oil well near Sarnia, Ontario Petroleum (from Greek petra â€“ rock and elaion â€“ oil or Latin oleum â€“ oil ) or crude oil is a thick, dark brown or greenish liquid. ...

However redox reactions of alkanes, in particular with oxygen and the halogens, are possible as the carbon atoms are in a strongly-reduced condition; in the case of methane, the lowest possible oxidation state for carbon (−4) is reached. Reaction with oxygen leads to combustion without any smoke; with halogens, substitution. In addition, alkanes have been shown to interact with, and bind to, certain transition metal complexes in (See: carbon-hydrogen bond activation). Substitution in the context of organic chemistry has the general meaning of replacing an atom, a functional group, or a substituent in a molecule. ... Carbon-hydrogen bond activation or CH activation may be defined as a facile carbon hydrogen cleavage reaction with an organometallic â€œMXâ€ species that proceeds by coordination of a hydrocarbon to the inner-sphere of â€œMâ€ (either via an intermediate â€œalkane or arene complexâ€ or a transition state) leading to a...

Free radicals, molecules with unpaired electrons, play a large role in most reactions of alkanes, such as cracking and reformation where long-chain alkanes are converted into shorter-chain alkanes and straight-chain alkanes into branched-chain isomers. In chemistry free radicals are uncharged atomic or molecular species with unpaired electrons or an otherwise open shell configuration. ...

In highly-branched alkanes, the bond angle may differ significantly from the optimal value (109.5°) in order to allow the different groups sufficient space. This causes a tension in the molecule, known as steric hindrance, and can substantially increase the reactivity. Steric effects are the interaction of molecules dictated by their shape and/or spatial relationships. ...

Reactions with oxygen

All alkanes react with oxygen in a combustion reaction, although they become increasingly difficult to ignite as the number of carbon atoms increases. The general equation for complete combustion is: This article is about the chemical element and its most stable form, or dioxygen. ... This article is about the chemical reaction combustion. ...

In the absence of sufficient oxygen, carbon monoxide or even soot can be formed, as shown below: Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ... Soot, also called lampblack, Pigment Black 7, carbon black or black carbon, is a dark powdery deposit of unburned fuel residues, usually composed mainly of amorphous carbon, that accumulates in chimneys, automobile mufflers and other surfaces exposed to smokeâ€”especially from the combustion of carbon-rich organic fuels in the...

for example methane: This article is about the chemical element and its most stable form, or dioxygen. ... This article is about the chemistry of hydrogen. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ... Methane is a chemical compound with the molecular formula . ...

See the alkane heat of formation table for detailed data. The standard enthalpy change of combustion, Δ_cH^o, for alkanes increases by about 650 kJ/mol per CH₂ group. Branched-chain alkanes have lower values of Δ_cH^o than straight-chain alkanes of the same number of carbon atoms, and so can be seen to be somewhat more stable. These tables include heat of formation data gathered from a variety of sources, including the primary and secondary literature, as well as the NIST Chemistry WebBook. ... The standard enthalpy of combustion is the enthalpy change when one mole of a substance completely reacts with oxygen under standard thermodynamic conditions (although experimental values are usually obtained under different conditions and subsequently adjusted). ...

Reactions with halogens

Alkanes react with halogens in a so-called free radical halogenation reaction. The hydrogen atoms of the alkane are progressively replaced by halogen atoms. Free-radicals are the reactive species that participate in the reaction, which usually leads to a mixture of products. The reaction is highly exothermic, and can lead to an explosion. This reaction is typical of alkanes and alkyl-substituted aromatics. ... This article is about the chemical series. ... Radical (chemistry) Free Radical Design This is a disambiguation page: a list of articles associated with the same title. ... In chemistry, an exothermic reaction is one that releases heat. ...

These reactions are an important industrial route to halogenated hydrocarbons. There are three steps:

Experiments have shown that all halogenation produces a mixture of all possible isomers, indicating that all hydrogen atoms are susceptible to reaction. The mixture produced, however, is not a statistical mixture: Secondary and tertiary hydrogen atoms are preferentially replaced due to the greater stability of secondary and tertiary free-radicals. An example can be seen in the monobromination of propane:^[7] In chemistry, homolysis is chemical bond dissociation of a neutral molecule generating two free radicals. ...

Image File history File links Size of this preview: 800 Ã— 286 pixelsFull resolution (1774 Ã— 634 pixel, file size: 12 KB, MIME type: image/png) monobromination of en:propane Reference: Organic Chemistry by Morisson & Boyd, 6th Edition. ...

Cracking

Cracking breaks larger molecules into smaller ones. This can be done with a thermal or catalytic method. The thermal cracking process follows a homolytic mechanism with formation of free-radicals. The catalytic cracking process involves the presence of acid catalysts (usually solid acids such as silica-alumina and zeolites), which promote a heterolytic (asymmetric) breakage of bonds yielding pairs of ions of opposite charges, usually a carbocation and the very unstable hydride anion. Carbon-localized free-radicals and cations are both highly unstable and undergo processes of chain rearrangement, C-C scission in position beta (i.e., cracking) and intra- and intermolecular hydrogen transfer or hydride transfer. In both types of processes, the corresponding reactive intermediates (radicals, ions) are permanently regenerated, and thus they proceed by a self-propagating chain mechanism. The chain of reactions is eventually terminated by radical or ion recombination. Factory of Shukhov cracking process, Baku, USSR, 1934 In petroleum geology and chemistry, cracking is the process whereby complex organic molecules such as kerogens or heavy hydrocarbons are broken down into simpler molecules (e. ... In chemistry, homolysis or homolytic fission is chemical bond dissociation of a neutral molecule generating two free radicals. ... Radical (chemistry) Free Radical Design This is a disambiguation page: a list of articles associated with the same title. ... For other uses, see acid (disambiguation). ... It has been suggested that this article or section be merged into Catalysis. ... Silica-alumina, also known as alumino-silicate(s). ... Zeolite The micro-porous molecular structure of a zeolite, ZSM-5 Zeolites (Greek, zein, to boil; lithos, a stone) are minerals that have a micro-porous structure. ... This article is about the electrically charged particle. ... A cation is an ion with positive charge. ... Hydride is the name given to the negative ion of hydrogen, Hâˆ’. Although this ion does not exist except in extraordinary conditions, the term hydride is widely applied to describe compounds of hydrogen with other elements, particularly those of groups 1â€“16. ... An anion is an ion with negative charge. ... The initial step in the chemistry of thermal cracking of hydrocarbons is the formation of free radicals. ... Intramolecular describes a process or characteristic limited within the structure of a single, or each molecule; a property or phenomenon limited to the extent of a single, or each molecule. ... Intermolecular describes a process or characteristic that extends from one molecule to an adjacent one; a property or phenomenon that extends from one molecule to another. ... Hydride is the name given to the negative ion of hydrogen, Hâˆ’. Although this ion does not exist except in extraordinary conditions, the term hydride is widely applied to describe compounds of hydrogen with other elements, particularly those of groups 1â€“16. ... In chemistry a reactive intermediate is a short-lived high energy highly reactive molecule. ...

Isomerization and reformation

Isomerization and reformation are processes in which straight-chain alkanes are heated in the presence of a platinum catalyst. In isomerization, the alkanes become branched-chain isomers. In reformation, the alkanes become cycloalkanes or aromatic hydrocarbons, giving off hydrogen as a by-product. Both of these processes raise the octane number of the substance. General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... cyclobutane Cycloalkanes (also called naphthenes) are chemical compounds with one or more carbon rings to which hydrogen atoms are attached according to the formula CnH2n. ... An aromatic hydrocarbon (abbreviated as AH) or arene [1] is a hydrocarbon, the molecular structure of which incorporates one or more planar sets of six carbon atoms that are connected by delocalised electrons numbering the same as if they consisted of alternating single and double covalent bonds. ... The octane rating is the most important characteristic of gasoline (petrol) and other fuels used in spark-ignition internal combustion engines. ...

Other reactions

Alkanes will react with steam in the presence of a nickel catalyst to give hydrogen. Alkanes can by chlorosulfonated and nitrated, although both reactions require special conditions. The fermentation of alkanes to carboxylic acids is of some technical importance. In the Reed reaction, sulfur dioxide, chlorine and light convert hydrocarbons to sulfonyl chlorides. For other uses, see Steam (disambiguation). ... For other uses, see Nickel (disambiguation). ... It has been suggested that this article or section be merged into Catalysis. ... This article is about the chemistry of hydrogen. ... Nitration is a general chemical process for the introduction of a nitro group in a chemical compound by means of a chemical reaction. ... For other uses, see Fermentation. ... Structure of a carboxylic acid The 3D structure of the carboxyl group A space-filling model of the carboxyl group Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -C(=O)OH, usually written -COOH or -CO2H. [1] Carboxylic acids are Bronsted... The Reed reaction is a chemical reaction that utilizes light to oxidize hydrocarbons to sulfonyl chlorides. ... Sulfur dioxide (or Sulphur dioxide) has the chemical formula SO2. ... General Name, symbol, number chlorine, Cl, 17 Chemical series nonmetals Group, period, block 17, 3, p Appearance yellowish green Standard atomic weight 35. ... Photochemistry is the study of the interaction of light and chemicals. ... It has been suggested that Sulfonic acid/Temp be merged into this article or section. ...

Hazards

Methane is explosive when mixed with air (1 – 8% CH₄) and is a strong greenhouse gas: Other lower alkanes can also form explosive mixtures with air. The lighter liquid alkanes are highly flammable, although this risk decreases with the length of the carbon chain. Pentane, hexane, heptane, and octane are classed as dangerous for the environment and harmful. The straight-chain isomer of hexane is a neurotoxin, and therefore rarely used commercially. Top: Increasing atmospheric levels as measured in the atmosphere and ice cores. ... A neurotoxin is a toxin that acts specifically on nerve cells â€“ neurons â€“ usually by interacting with membrane proteins such as ion channels. ...

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