Decane is an alkane hydrocarbon with the chemical formula C 10 H 22. Although 75 structural isomers are possible for decane, the term usually refers to the normal.

1. Thermal Cracking Of Alkane

1. Cracking of Decane. Chemical Equations. Cracking allows the excess of large hydrocarons to be converted to smaller hydrocarbons and hence cracking is.
2. What is the symbol equation for the cracking of decane. What would you like to do? The Chemistry of the Cracking of Hydrocarbons including the Conditions and Catalyst.

Chemical structure of, the simplest alkane In, an alkane, or paraffin (a historical name that also has ), is an. In other words, an alkane consists of and atoms arranged in a structure in which all the are. Alkanes have the general chemical formula n 2 n+2. The alkanes range in complexity from the simplest case of, CH 4 where n = 1 (sometimes called the parent molecule), to arbitrarily large molecules. Besides this standard definition by, in some authors' usage the term alkane is applied to any saturated hydrocarbon, including those that are either monocyclic (i.e. The ) or polycyclic. In an alkane, each carbon atom has 4 bonds (either C-C or ), and each hydrogen atom is joined to one of the carbon atoms (so in a C-H bond).

The longest series of linked carbon atoms in a molecule is known as its or carbon backbone. The number of carbon atoms may be thought of as the size of the alkane. One group of the are, solids at standard and pressure (SATP), for which the number of carbons in the carbon backbone is greater than about 17. With their repeated -CH 2- units, the alkanes constitute a of organic compounds in which the members differ in by multiples of 14.03 (the total mass of each such unit, which comprises a single carbon atom of mass 12.01 u and two hydrogen atoms of mass 1.01 u each). Alkanes are not very reactive and have little. They can be viewed as molecular trees upon which can be hung the more active/reactive of biological molecules. The alkanes have two main commercial sources: (crude oil) and.

An group, generally abbreviated with the symbol R, is a functional group that, like an alkane, consists solely of single-bonded carbon and hydrogen atoms connected acyclically—for example, a. Contents. Structure classification Saturated hydrocarbons are having only single covalent bonds between their carbons. They can be:. linear (general formula C nH 2 n+2) wherein the carbon atoms are joined in a snake-like structure. branched (general formula C nH 2 n+2, n  2) wherein the carbon backbone splits off in one or more directions.

(general formula C nH 2 n, n  3) wherein the carbon backbone is linked so as to form a loop. According to the definition by, the former two are alkanes, whereas the third group is called.

Saturated hydrocarbons can also combine any of the linear, cyclic (e.g., polycyclic) and branching structures; the general formula is C nH 2 n−2 k+2, where k is the number of independent loops. Alkanes are the (loopless) ones, corresponding to k = 0. Isomerism. Alkanes with more than three atoms can be arranged in various different ways, forming. 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. For example, for acyclic alkanes:. C 1: only. C 2: only.

C 3: only. C 4: 2 isomers: and.

C 5: 3 isomers:, and. C 6: 5 isomers:, and. C 12: 355 isomers. C 32: 27,711,253,769 isomers. C 60: 22,158,734,535,770,411,074,184 isomers, many of which are not stable. Branched alkanes can be. For example, and its higher are chiral due to their at carbon atom number 3.

In addition to the alkane isomers, the chain of carbon atoms may form one or more loops. Such compounds are called. Stereoisomers and cyclic compounds are excluded when calculating the number of isomers above.

Nomenclature. Main article: The (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'. In 1866, 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 C nH 2 n+2, C nH 2 n, C nH 2 n−2, C nH 2 n−4, C nH 2 n−6. Now, the first three name hydrocarbons with single, double and triple bonds; '-one' represents a; '-ol' represents an alcohol or OH group; '-oxy-' means an and refers to oxygen between two carbons, so that methoxymethane is the IUPAC name for. It is difficult or impossible to find compounds with more than one 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. 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 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., or 2- or 3-methylpentane.

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Alternative names for this group are: linear paraffins or n-paraffins. The members of the series (in terms of number of carbon atoms) are named as follows: CH 4 – one carbon and four hydrogen C 2H 6 – two carbon and six hydrogen C 3H 8 – three carbon and 8 hydrogen C 4H 10 – four carbon and 10 hydrogen C 5H 12 – five carbon and 12 hydrogen C 6H 14 – six carbon and 14 hydrogen The first four names were from, and, respectively ( is also sometimes referred to as cetane). Alkanes with five or more carbon atoms are named by adding the -ane to the appropriate prefix with elision of any terminal vowel ( -a or -o) from the basic numerical term. Hence, C 5H 12;, C 6H 14;, C 7H 16;, C 8H 18; etc.

The prefix is generally Greek, however alkanes with a carbon atom count ending in nine, for example, use the prefix non. For a more complete list, see. Branched alkanes.

Of (common name) or 2-methylbutane (IUPAC systematic name) Simple branched alkanes often have a common name using a prefix to distinguish them from linear alkanes, for example, and. IUPAC naming conventions can be used to produce a systematic name.

The key steps in the naming of more complicated branched alkanes are as follows:. Identify the longest continuous chain of carbon atoms. Name this longest root chain using standard naming rules. Name each side chain by changing the suffix of the name of the alkane from '-ane' to '-yl'. Number the root chain in order to give the lowest possible numbers for the side-chains. Number and name the side chains before the name of the root chain. If there are multiple side chains of the same type, use prefixes such as 'di-' and 'tri-' to indicate it as such, and number each one.

Add side chain names in alphabetical (disregarding 'di-' etc. Prefixes) order in front of the name of the root chain Comparison of nomenclatures for three isomers of C 5H 12 Common name n-pentane isopentane neopentane IUPAC name pentane 2-methylbutane 2,2-dimethylpropane Structure Saturated cyclic hydrocarbons. Main article: Though technically distinct from the alkanes, this class of hydrocarbons is referred to by some as the 'cyclic alkanes.' As their description implies, they contain one or more rings. 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 in their backbones, e.g., (C 5H 10) is a cycloalkane with 5 carbon atoms just like (C 5H 12), but they are joined up in a five-membered ring. In a similar manner, and, and, etc.

Substituted cycloalkanes are named similarly to substituted alkanes — the cycloalkane ring is stated, and the substituents are according to their position on the ring, with the numbering decided by the. Trivial/common names The trivial (non-) 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. It is almost certain that the term paraffin stems from the.

Branched-chain alkanes are called isoparaffins. The use of the term 'paraffin' is a general term and often does not distinguish between pure compounds and mixtures of, i.e., compounds of the same, e.g., and. Examples The following trivial names are retained in the IUPAC system:. for 2-methylpropane. for 2-methylbutane. for 2,2-dimethylpropane.

Physical properties All alkanes are colourless and odourless. Melting (blue) and boiling (orange) points of the first 16 n-alkanes in °C. Alkanes experience intermolecular. Stronger intermolecular van der Waals forces give rise to greater boiling points of alkanes. There are two determinants for the strength of the van der Waals forces:.

the number of electrons surrounding the, which increases with the alkane's molecular weight. the surface area of the molecule Under, from CH 4 to C 4H 10 alkanes are gaseous; from C 5H 12 to C 17H 36 they are liquids; and after C 18H 38 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 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.

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 (2-methylpropane) and (butane), which boil at −12 and 0 °C, and 2,2-dimethylbutane and 2,3-dimethylbutane which boil at 50 and 58 °C, respectively. 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.

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. Melting points The of the alkanes follow a similar trend to 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 rigid and fixed structure than liquids. This rigid structure requires energy to break down.

Thus the 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 than even numbered alkanes. This is because even numbered alkanes pack well in the solid phase, forming a well-organized structure, which requires more energy to break apart.

The odd-numbered alkanes pack less well and so the 'looser' organized solid packing structure requires less energy to break apart. 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 pack well in the solid phase: This is particularly true for (2-methyl isomers), which often have melting points higher than those of the linear analogues. Conductivity and solubility Alkanes do not conduct electricity, nor are they substantially by an.

For this reason, they do not form 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 ).

As there is no significant bonding between water molecules and alkane molecules, the suggests that this reduction in entropy should be minimized by minimizing the contact between alkane and water: Alkanes are said to be in that they repel water. Their solubility in nonpolar solvents is relatively good, a property that is called.

Different alkanes are, for example, miscible in all proportions among themselves. The density of the alkanes usually increases with the number of carbon atoms but remains less than that of water. Hence, alkanes form the upper layer in an alkane–water mixture. Molecular geometry. Sp 3-hybridization in. The molecular structure of the alkanes directly affects their physical and chemical characteristics. It is derived from the of, which has four.

The carbon atoms in alkanes are always, 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, the angle of cos −1(− 1 / 3) ≈ 109.47° between them. Bond lengths and bond angles An alkane molecule has only C–H and C–C single bonds. The former result from the overlap of an sp 3 orbital of carbon with the 1s orbital of a hydrogen; the latter by the overlap of two sp 3 orbitals on different carbon atoms. The amount to 1.09 × 10 −10 m for a C–H bond and 1.54 × 10 −10 m for a C–C bond. Of the two rotamers of 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.

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: conformation and. The two conformations, also known as, differ in energy: The staggered conformation is 12.6 kJ/mol lower in energy (more stable) than the eclipsed conformation (the least stable).

This difference in energy between the two conformations, known as the, 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 CH 3 group by 120° relative to the other, is of the order of 10 −11 seconds. The case of is more complex but based on similar principles, with the antiperiplanar conformation always being the most favored 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 idealized 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 of a different functional group like, etc. Infrared spectroscopy The carbon–hydrogen stretching mode gives a strong absorption between 2850 and 2960, while the carbon–carbon stretching mode absorbs between 800 and 1300 cm −1. The carbon–hydrogen bending modes depend on the nature of the group: methyl groups show bands at 1450 cm −1 and 1375 cm −1, while methylene groups show bands at 1465 cm −1 and 1450 cm −1. Carbon chains with more than four carbon atoms show a weak absorption at around 725 cm −1.

NMR spectroscopy The proton resonances of alkanes are usually found at = 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, –CH 3), 15–55 (secondary, methylene, –CH 2–), 20–60 (tertiary, methyne, C–H) and quaternary. The carbon-13 resonance of quaternary carbon atoms is characteristically weak, due to the lack of and the long, and can be missed in weak samples, or samples that have not been run for a sufficiently long time. Mass spectrometry Alkanes have a high, 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. The fragment resulting from the loss of a single methyl group ( M − 15) is often absent, and other fragments are often spaced by intervals of fourteen mass units, corresponding to sequential loss of CH 2 groups.

Chemical properties Alkanes are only weakly reactive with ionic and other polar substances. The (pK a) values of all alkanes are above 60, hence they are practically inert to acids and bases (see: ). This inertness is the source of the term paraffins (with the meaning here of 'lacking affinity'). In the alkane molecules have remained chemically unchanged for millions of years.

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 ( if present in sufficient quantity to satisfy the reaction ) leads to combustion without any smoke, producing and water. Reactions occur with halogens, leading to the production of. In addition, alkanes have been shown to interact with, and bind to, certain transition metal complexes in., 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 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, and can substantially increase the reactivity.

Reactions with oxygen (combustion reaction) All alkanes react with in a reaction, although they become increasingly difficult to ignite as the number of carbon atoms increases. The general equation for complete combustion is: C nH 2 n+2 + ( 3 / 2 n + 1 / 2) O 2 → ( n + 1) H 2O + n CO 2 or C nH 2 n+2 + ( 3 n + 1 / 2) O 2 → ( n + 1) H 2O + n CO 2 In the absence of sufficient oxygen, or even can be formed, as shown below: C nH 2 n+2 + ( n + 1 / 2) → ( n + 1) H 2O + n C nH 2 n+2 + ( 1 / 2 n + 1 / 2) → ( n + 1) H 2O + n For example,: 2 CH 4 + 3 O 2 → 2 CO + 4 H 2O CH 4 + 3 / 2 O 2 → CO + 2 H 2O See the for detailed data. The, Δ c H o, for alkanes increases by about 650 kJ/mol per CH 2 group.

Branched-chain alkanes have lower values of Δ c H o than straight-chain alkanes of the same number of carbon atoms, and so can be seen to be somewhat more stable. Reactions with halogens. Main article: Alkanes react with in a so-called free radical halogenation reaction. The hydrogen atoms of the alkane are progressively replaced by halogen atoms. Are the reactive species that participate in the reaction, which usually leads to a mixture of products. The reaction is highly, and can lead to an explosion. These reactions are an important industrial route to halogenated hydrocarbons.

There are three steps:. Initiation the halogen radicals form. Usually, energy in the form of heat or light is required. Chain reaction or Propagation then takes place—the halogen radical abstracts a hydrogen from the alkane to give an alkyl radical. This reacts further.

Chain termination where the radicals recombine. 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. Main article: Cracking breaks larger molecules into smaller ones. This can be done with a thermal or catalytic method.

The thermal cracking process follows a mechanism with formation of. The catalytic cracking process involves the presence of (usually solid acids such as and ), which promote a (asymmetric) breakage of bonds yielding pairs of ions of opposite charges, usually a and the very unstable. Carbon-localized free radicals and cations are both highly unstable and undergo processes of chain rearrangement, C–C scission in position (i.e., cracking) and and hydrogen transfer or transfer. In both types of processes, the corresponding (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.

Isomerization and reformation Dragan and his colleague were the first to report about isomerization in alkanes. Isomerization and reformation are processes in which straight-chain alkanes are heated in the presence of a catalyst. In isomerization, the alkanes become branched-chain isomers.

In other words, it does not lose any carbons or hydrogens, keeping the same molecular weight. In reformation, the alkanes become or, giving off hydrogen as a by-product.

Both of these processes raise the of the substance. Butane is the most common alkane that is put under the process of isomerization, as it makes many branched alkanes with high octane numbers. Other reactions Alkanes will react with in the presence of a to give.

Alkanes can be and, although both reactions require special conditions. The of alkanes to is of some technical importance. In the, and convert hydrocarbons to. Can be used to separate an alkane from a metal. Alkyl groups can be transferred from one compound to another by reactions.

Occurrence. Extraction of oil, which contains many different including alkanes Alkanes form a small portion of the of the outer gas planets such as (0.1% methane, 2 ethane), (0.2% methane, 5 ppm ethane), (1.99% methane, 2.5 ppm ethane) and (1.5% methane, 1.5 ppm ethane).

(1.6% methane), a satellite of Saturn, was examined by the, which indicated that Titan's atmosphere periodically rains liquid methane onto the moon's surface. Also on Titan the Cassini mission has imaged seasonal methane/ethane lakes near the polar regions of Titan. And have also been detected in the tail of the comet. 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. Alkanes have also been detected in such as.

Occurrence of alkanes on Earth Traces of methane gas (about 0.0002% or 1745 ppb) occur in the Earth's atmosphere, produced primarily by microorganisms, such as in the gut of ruminants. The most important commercial sources for alkanes are natural gas and. Natural gas contains primarily methane and ethane, with some and: oil is a mixture of liquid alkanes and other. These hydrocarbons were formed when marine animals and plants (zooplankton and phytoplankton) died and sank to the bottom of ancient seas and were covered with sediments in an 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: C 6H 12O 6 → 3 CH 4 + 3 CO 2 These hydrocarbon deposits, collected in porous rocks trapped beneath impermeable cap rocks, comprise commercial. They have formed over millions of years and once exhausted cannot be readily replaced. The depletion of these hydrocarbons reserves is the basis for what is known as the.

Methane is also present in what is called, produced by animals and decaying matter, which is a possible. 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). Although this cannot be commercially exploited at the present time, the amount of combustible energy of the known methane clathrate fields exceeds the energy content of all the natural gas and oil deposits put together. Methane extracted from methane clathrate is, therefore, a candidate for future fuels. Biological occurrence Acyclic alkanes occur in nature in various ways. Bacteria and archaea. In the gut of this cow are responsible for some of the in Earth's atmosphere.

Certain types of bacteria can metabolize alkanes: they prefer even-numbered carbon chains as they are easier to degrade than odd-numbered chains. On the other hand, certain, the, produce large quantities of by the metabolism of or other organic compounds. The energy is released by the oxidation of: CO 2 + 4 H 2 → CH 4 + 2 H 2O Methanogens are also the producers of in, and release about two billion tonnes of methane per year —the atmospheric content of this gas is produced nearly exclusively by them.

The methane output of and other, which can release up to 150 liters per dayand ofis also due to methanogens. They also produce this simplest of all alkanes in the of humans. Methanogenic archaea are, hence, at the end of the, with carbon being released back into the atmosphere after having been fixed. It is probable that our current deposits of natural gas were formed in a similar way. Fungi and plants Alkanes also play a role, if a minor role, in the biology of the three groups of organisms:, plants and animals.

Some specialized yeasts, e.g., Candida tropicale, sp., sp., can use alkanes as a source of carbon or energy. The fungus prefers the longer-chain alkanes in, and can cause serious problems for aircraft in tropical regions.

Thermal Cracking Of Alkane

In plants, the solid long-chain alkanes are found in the and of many species, but are only rarely major constituents. They protect the plant against water loss, prevent the of important minerals by the rain, and protect against bacteria, fungi, and harmful insects. The carbon chains in plant alkanes are usually odd-numbered, between 27 and 33 carbon atoms in length and are made by the plants by of even-numbered. 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.

More volatile short-chain alkanes are also produced by and found in plant tissues. The is noted for producing exceptionally high levels of n- in its resin, for which reason its distillate was designated as the zero point for one. Floral scents have also long been known to contain volatile alkane components, and n- is a significant component in the scent of some. Emission of gaseous and volatile alkanes such as, and by plants has also been documented at low levels, though they are not generally considered to be a major component of biogenic air pollution.

Edible vegetable oils also typically contain small fractions of biogenic alkanes with a wide spectrum of carbon numbers, mainly 8 to 35, usually peaking in the low to upper 20s, with concentrations up to dozens of milligrams per kilogram (parts per million by weight) and sometimes over a hundred for the total alkane fraction. Animals 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% (2,6,10,14-tetramethylpentadecane, C 19H 40). They are important as, chemical messenger materials, on which insects depend for communication.

In some species, e.g. The support beetle, (C 25H 52), 3-methylpentaicosane (C 26H 54) and 9-methylpentaicosane (C 26H 54) are transferred by body contact. With others like the Glossina morsitans morsitans, the pheromone contains the four alkanes 2-methylheptadecane (C 18H 38), 17,21-dimethylheptatriacontane (C 39H 80), 15,19-dimethylheptatriacontane (C 39H 80) and 15,19,23-trimethylheptatriacontane (C 40H 82), and acts by smell over longer distances. Produce and release two alkanes, tricosane and pentacosane. Ecological relations.

Early spider orchid ( ) One example, in which both plant and animal alkanes play a role, is the ecological relationship between the ( ) and the ( ); the latter is dependent for 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 (C 23H 48), (C 25H 52) and (C 27H 56) in the ratio 3:3:1, and males are attracted by specifically this odor. 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 endeavor 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. Production Petroleum refining. As stated earlier, the most important source of alkanes is natural gas and. Alkanes are separated in an by and processed into many different products.

Fischer–Tropsch The is a method to synthesize liquid hydrocarbons, including alkanes, from and hydrogen. This method is used to produce substitutes for. 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 unreactive chemically or biologically, and do not undergo cleanly. When alkanes are produced in the laboratory, it is often a side-product of a reaction.

For example, the use of as a strong gives the conjugate acid, n-butane as a side-product: C 4H 9Li + H 2O → C 4H 10 + However, at times it may be desirable to make a section of a molecule into an alkane-like functionality ( group) using the above or similar methods. For example, an is an alkyl group; when this is attached to a group, it gives, which is not an alkane.

To do so, the best-known methods are of: RCH=CH 2 + H 2 → RCH 2CH 3 (R = ) Alkanes or alkyl groups can also be prepared directly from in the. The removes hydroxyl groups from alcohols e.g.

And the removes carbonyl groups from aldehydes and ketones to form alkanes or alkyl-substituted compounds e.g.: Applications The applications of alkanes depend on the number of carbon atoms. The first four alkanes are used mainly for heating and cooking purposes, and in some countries for electricity generation. And 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. And are gases at atmospheric pressure that can be liquefied at fairly low pressures and are commonly known as (LPG). Propane is used in propane gas burners and as a fuel for road vehicles, butane in space heaters and disposable cigarette lighters. Both are used as propellants in.

From to the alkanes are highly volatile liquids. They are used as fuels in, as they vaporize 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, than their straight-chain homologues.

This propensity to premature ignition is measured by the of the fuel, where ( isooctane) has an arbitrary value of 100, and has a value of zero. Apart from their use as fuels, the middle alkanes are also good for nonpolar substances.

Alkanes from to, for instance, (an alkane with sixteen carbon atoms) are liquids of higher, less and less suitable for use in gasoline. They form instead the major part of and.

Diesel fuels are characterized by their, 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. Alkanes from hexadecane upwards form the most important components of and.

In the 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, for example, in. This should not be confused however with true, which consists primarily of. Alkanes with a chain length of approximately 35 or more carbon atoms are found in, used, for example, in road surfacing.

However, the higher alkanes have little value and are usually split into lower alkanes. Some synthetic such as and 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. Environmental transformations. This section needs expansion.

You can help. (August 2014) Alkanes are chemically very inert apolar molecules which are not very reactive as organic compounds. This inertness yields serious ecological issues if they are released into the environment. Due to their lack of functional groups and low water solubility, alkanes show poor bioavailability for microorganisms. There are, however, some microorganisms possessing the metabolic capacity to utilize n-alkanes as both carbon and energy sources. Some bacterial species are highly specialised in degrading alkanes; these are referred to as hydrocarbonoclastic bacteria.

This section needs expansion. You can help. (September 2017) Methane is flammable, explosive and dangerous to inhale, because it is a colorless, odorless gas, special caution must be taken around methane.

Ethane is also extremely flammable, dangerous to inhale and explosive. Both of these may cause suffocation. Similarly, propane is flammable and explosive. It may cause drowsiness or unconsciousness if inhaled. Butane has the same hazards to consider as propane.

Alkanes also pose a threat to the environment. Branched alkanes have a lower biodegradability than unbranched alkanes. However, methane is ranked as the most dangerous greenhouse gas. Although the amount of methane in the atmosphere is low, it does pose a threat to the environment. See also Wikimedia Commons has media related to. Look up in Wiktionary, the free dictionary. Retrieved 14 June 2016.

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