Visionlearning | Chemistry | Carbon Chemistry Carbon Chemistry bonding : the act of linking two atoms together formula : an expression of the composition of a chemical compound using symbols property : a characteristic; an attribute Glossary Terms To understand life as we know it, we must first understand a little bit of organic chemistry. Organic molecules contain both carbon and hydrogen. Though many organic chemicals also contain other elements , it is the carbon-hydrogen bond that defines them as organic. Organic chemistry defines life. Just as there are millions of different types of living organisms on this planet, there are millions of different organic molecules , each with different chemical and physical properties. There are organic chemicals that make up your hair, your skin, your fingernails, and so on. The diversity of organic chemicals is due to the versatility of the carbon atom . Why is carbon such a special element? Let's look at its chemistry in a little more detail. The uniqueness of carbon Carbon (C) appears in the second row of the periodic table and has four bonding electrons in its valence shell (see our Periodic Table module for more information). Similar to other non-metals, carbon needs eight electrons to satisfy its valence shell .

Carbon therefore forms four bonds with other atoms (each bond consisting of one of carbon's electrons and one of the bonding atom's electrons). Every valence electron participates in bonding; thus, a carbon atom's bonds will be distributed evenly over the atom's surface . These bonds form a tetrahedron (a pyramid with a spike at the top), as illustrated below: Carbon forms 4 bonds Organic chemicals get their diversity from the many different ways carbon can bond to other atoms . The simplest organic chemicals, called hydrocarbons , contain only carbon and hydrogen atoms; the simplest hydrocarbon (called methane) contains a single carbon atom bonded to four hydrogen atoms: Methane - a carbon atom bonded to 4 hydrogen atoms But carbon can bond to other carbon atoms in addition to hydrogen, as illustrated in the molecule ethane below: Ethane - a carbon-carbon bond In fact, the uniqueness of carbon comes from the fact that it can bond to itself in many different ways. Carbon atoms can form long chains: Hexane - a 6-carbon chain Decane C10H22 The chemical formula for any alkane is given by the expression CnH2n+2.

The structural formula, shown for the first five alkanes in the table, shows each carbon atom and the elements that are attached to it. This structural formula is important when we begin to discuss more complex hydrocarbons . The simple alkanes share many properties in common. All enter into combustion reactions with oxygen to produce carbon dioxide and water vapor. In other words, many alkanes are flammable. This makes them good fuels. For example, methane is the main component of natural gas , and butane is common lighter fluid . CH4 The chemical reaction between a fuel (for example wood) and an oxidizing agent. Alkenes The second class of simple hydrocarbons , the alkenes , consists of molecules that contain at least one double-bonded carbon pair. Alkenes follow the same naming convention used for alkanes . A prefix (to describe the number of carbon atoms) is combined with the ending "ene" to denote an alkene. Ethene, for example is the two-carbon molecule that contains one double bond . The chemical formula for the simple alkenes follows the expression CnH2n.

Because one of the carbon pairs is double bonded, simple alkenes have two fewer hydrogen atoms than alkanes. Ethene Alkynes Alkynes are the third class of simple hydrocarbons and are molecules that contain at least one triple-bonded carbon pair. Like the alkanes and alkenes , alkynes are named by combining a prefix with the ending "yne" to denote the triple bond . The chemical formula for the simple alkynes follows the expression CnH2n-2. Ethyne b.false Functional groups In addition to carbon and hydrogen, hydrocarbons can also contain other elements . In fact, many common groups of atoms can occur within organic molecules , these groups of atoms are called functional groups. One good example is the hydroxyl functional group. The hydroxyl group consists of a single oxygen atom bound to a single hydrogen atom (-OH). The group of hydrocarbons that contain a hydroxyl functional group is called alcohols . The alcohols are named in a similar fashion to the simple hydrocarbons, a prefix is attached to a root ending (in this case "anol") that designates the alcohol. The existence of the functional group completely changes the chemical properties of the molecule.

Ethane, the two-carbon alkane, is a gas at room temperature; ethanol, the two-carbon alcohol, is a liquid . Ethanol Ethanol, common drinking alcohol , is the active ingredient in "alcoholic" beverages such as beer and wine. Summary The chemical basis of all living organisms is linked to the way that carbon bonds with other atoms. This introduction to organic chemistry explains the many ways that carbon and hydrogen form bonds. Basic hydrocarbon nomenclature is described, including alkanes, alkenes, alkynes, and isomers. Functional groups of atoms within organic molecules are discussed. NGSS Organic Chemistry/Alkanes - Wikibooks, open books for an open world Organic Chemistry/Alkanes Jump to: navigation , search Alkanes are the simplest organic molecules, consisting of only carbon and hydrogen and with only single bonds between carbon atoms. Alkanes are used as the basis for naming the majority of organic compounds (their nomenclature). Alkanes have the general formula CnH2n+2. Contents 2,2-dimethylpropane or neopentane.

An example of an alkane Alkanes are the simplest and least reactive hydrocarbon species containing only carbons and hydrogens. They are commercially very important, being the principal constituent of gasoline and lubricating oils and are extensively employed in organic chemistry; though the role of pure alkanes (such as hexanes) is delegated mostly to solvents. The distinguishing feature of an alkane, making it distinct from other compounds that also exclusively contain carbon and hydrogen, is its lack of unsaturation . That is to say, it contains no double or triple bonds, which are highly reactive in organic chemistry. Though not totally devoid of reactivity, their lack of reactivity under most laboratory conditions makes them a relatively uninteresting, though very important component of organic chemistry. As you will learn about later, the energy confined within the carbon-carbon bond and the carbon-hydrogen bond is quite high and their rapid oxidation produces a large amount of heat, typically in the form of fire. As said it is important, not considered very important component in the chemistry. Introductory Definitions[ edit ] Organic compounds contain carbon and hydrogen by definition and usually other elements (e.g. nitrogen and oxygen) as well.

(CO2 is not an organic compound because it has no hydrogen). Hydrocarbons are organic compounds that contain carbon and hydrogen only. Alkanes are hydrocarbons or organic compounds made up of only carbon-carbon single bonds (as opposed to double and triple bonds). The simplest alkane is methane . Methane, (CH4, one carbon bonded to four hydrogens) is the simplest organic molecule. It is a gas at standard temperature and pressure (STP) . Methane This is a flattened, two-dimensional representation of methane that you will see commonly. The true three-dimensional form of methane does not have any 90 degree angles between bonded hydrogens. The bonds point to the four corners of a tetrahedron , forming cos-1(-1/3) ≈ 109.5 degree bond angles. A balloon model of the electron clouds repelling each other in a molecule of methane. Ethane[ edit ] Two carbons singly bonded to each other with six hydrogens is called ethane . Ethane is the second simplest hydrocarbon molecule. It can be thought of as two methane molecules attached to each other, but with two fewer hydrogen atoms. There are several common methods to draw organic molecules.

You will use them interchangeably although sometimes one will work better for one situation or another. Drawing alkanes[ edit ] When writing out the alkane structures, you can use different levels of shorthand depending on the needs at hand in hand. For example, pentane can be written out. Its formula is C5H12. , or CH3–CH2–CH2–CH2–CH3, or CH3(CH2)3CH3, or minimized to Line drawing shorthand[ edit ] Although non-cyclic alkanes are called straight-chain alkanes they are technically made of linked chains. This is reflected in the line-drawing method. Each ending point and bend in the line represents one carbon atom and each short line represents one single carbon-carbon bond. Every carbon is assumed to be surrounded with a maximum number of hydrogen atoms unless shown otherwise. Propane, butane, pentane Structures drawn without explicitly showing all carbon atoms are often called "skeletal" structures, since they represent the skeleton or the backbone of the molecule. In organic chemistry, carbon is very frequently used, so chemists know that there is a carbon atom at the endpoints of every line that is not specifically labeled.

Conformations[ edit ] Conformers, also called conformational isomers, or rotational isomers,or rotomers are arrangements of the same molecule made transiently different by the rotation in space about one or more single bonds. Other types of isomer can only be converted from one form to another by breaking bonds, but conformational isomers can be made simply by rotating bonds. Newman projections[ edit ] Newman projections are drawings used to represent different positions of parts of molecules relative to each other in space. Remember that single bonds can rotate in space if not impeded. Newman projections represent different positions of rotating molecule parts. Conformers interconvert readily, normally thousands of times a second as parts of molecules spin. In the following drawings, methyl groups are on the front and back ends of the molecule and a circle represents all that lies between. Note: This is how methyl groups are represented in Newman projections Staggered conformation (front end overlaps the back and also unstable) Conformations and energy[ edit ] Different conformations have different potential energies. The staggered conformation is at a lower potential energy than the eclipsed conformation, and is favored.

In ethane, the barrier to rotation is approximately 25 kJ/mol, indicating that each pair of eclipsed hydrogens raises the energy by about 8 kJ/mol. This number also applies to other organic compounds which have hydrogen atoms at similar distances from each other. At very low temperatures all conformations revert to the stabler( due to minimized vibration of atoms at it's mean position) , lower energy staggered conformation. Steric effects[ edit ] Steric effects have to do with size. Two bulky objects run into each other and invade each others space. If we replace one or more hydrogen atoms on the above Newman projections with a methyl or other group, the potential energy goes up especially for the eclipsed conformations. Lets look at a Newman projection of butane as it rotates counterclockwise around its axes. Anti Gauche Eclipsed When the larger groups overlap they repel each other more strongly than do hydrogen, and the potential energy goes up. Entropy[ edit ] Entropy, represented as a ΔS, is a mathematical construct that represents disorder or probability. Natural systems want to find the lowest energy or organization possible, which translates to the highest entropy.

A note about potential energy: If you are rusty on this, remember the analogy of a big rock pushed to the top of a hill. At the top it has a maximum of potential energy. When you push it and allow it to roll down the hill the potential energy stored in it is transformed into kinetic energy that can be used to generate heat or smash something. Notice that statistically, the ethane molecule has twice as many opportunities to be in the gauche conformation as in the anti conformation. However, because the Gauche configuration brings the methyl groups closer together in space, this generates high energy steric interactions and do not occur without the input of energy. Thus, the butane molecules shown will almost never be found in such unfavorable conformations.

Preparation of Alkanes[ edit ] Wurtz reaction is coupling of haloalkanes using sodium metal in solvent like dry ether 2R-X + 2Na → R-R + 2Na+X− Mechanism[ edit ] The reaction consists of a halogen-metal exchange involving the free radical species R• (in a similar fashion to the formation of a Grignard reagent and then the carbon-carbon bond formation in a nucleophilic substitution reaction.) One electron from the metal is transferred to the halogen to produce a metal halide and an alkyl radical. R-X + M → R• + M+X− The alkyl radical then accepts an electron from another metal atom to form an alkyl anion and the metal becomes cationic. This intermediate has been isolated in a several cases. R• + M → R−M+ The nucleophilic carbon of the alkyl anion then displaces the halide in an SN2 reaction, forming a new carbon-carbon covalent bond.

R−M+ + R-X → R-R + M+X− COREY-HOUSE reactioN [Also called as 'coupling of alkyl halides with organo metallic compounds'] It is a better method than wurtz reaction. An alkyl halides and a lithium dialkyl copper are reacted to give a higher hydrocarbon R'-X + R2CuLi---->R-R' + R-Cu + LiX (R and R' may be same or different) It Clemmensen reduction[ edit ] Clemmensen reduction is a reduction of ketones (or aldehydes) to alkanes using zinc amalgam and hydrochloric acid The Clemmensen reduction is particularly effective at reducing aryl-alkyl ketones. With aliphatic or cyclic ketones, zinc metal reduction is much more effective The substrate must be stable in the strongly acidic conditions of the Clemmensen reduction. Acid sensitive substrates should be reacted in the Wolff-Kishner reduction, which utilizes strongly basic conditions; a further, milder method is the Mozingo reduction. As a result of Clemmensen Reduction, the carbon of the carbonyl group involved is converted from sp2 hybridisation to sp3 hybridisation.

The oxygen atom is lost in the form of one molecule of water. Wolff-Kishner reduction[ edit ] The Wolff–Kishner reduction is a chemical reaction that fully reduces a ketone (or aldehyde) to an alkane. Condensation of the carbonyl compound with hydrazine forms the hydrazone, and treatment with base induces the reduction of the carbon coupled with oxidation of the hydrazine to gaseous nitrogen, to yield the corresponding alkane. Mechanism[ edit ] The mechanism first involves the formation of the hydrazone in a mechanism that is probably analogous to the formation of an imine. Successive deprotonations eventually result in the evolution of nitrogen. The mechanism can be justified by the evolution of nitrogen as the thermodynamic driving force. This reaction is also used to distinguish between aldehydes and ketones. Mozingo Reduction[ edit ] A thioketal is first produced by reaction of the ketone with an appropriate thiol. The product is then hydrogenolyzed to the alkane, using Raney nickel Properties of Alkanes[ edit ] Alkane properties Alkanes are not very reactive when compared with other chemical species.

This is because the backbone carbon atoms in alkanes have attained their octet of electrons through forming four covalent bonds (the maximum allowed number of bonds under the octet rule; which is why carbon's valence number is 4). These four bonds formed by carbon in alkanes are sigma bonds, which are more stable than other types of bond because of the greater overlap of carbon's atomic orbitals with neighboring atoms' atomic orbitals. To make alkanes react, the input of additional energy is needed; either through heat or radiation. Gasoline is a mixture of the alkanes and unlike many chemicals, can be stored for long periods and transported without problem. It is only when ignited that it has enough energy to continue reacting. This property makes it difficult for alkanes to be converted into other types of organic molecules. (There are only a few ways to do this). Alkanes are also less dense than water, as one can observe, oil, an alkane, floats on water. Alkanes are non-polar solvents. Since only C and H atoms are present, alkanes are nonpolar. Alkanes are immiscible in water but freely miscible in other non-polar solvents.

Alkanes consisting of weak dipole dipole bonds can not break the strong hydrogen bond between water molecules hence it is not miscible in water. The same character is also shown by alkenes. Because alkanes contain only carbon and hydrogen, combustion produces compounds that contain only carbon, hydrogen, and/or oxygen. Like other hydrocarbons, combustion under most circumstances produces mainly carbon dioxide and water. However, alkanes require more heat to combust and do not release as much heat when they combust as other classes of hydrocarbons. Therefore, combustion of alkanes produces higher concentrations of organic compounds containing oxygen, such as aldehydes and ketones, when combusting at the same temperature as other hydrocarbons. The general formula for alkanes is CNH2N+2; the simplest possible alkane is therefore methane, CH4. The next simplest is ethane, C2H6; the series continues indefinitely. Each carbon atom in an alkane has sp³ hybridization. Alkanes are also known as paraffins, or collectively as the paraffin series. These terms are also used for alkanes whose carbon atoms form a single, unbranched chain.

Branched-chain alkanes are called isoparaffins. Methane through Butane are very flammable gases at standard temperature and pressure (STP). Pentane is an extremely flammable liquid boiling at 36 °C and boiling points and melting points steadily increase from there; octadecane is the first alkane which is solid at room temperature. Longer alkanes are waxy solids; candle wax generally has between C20 and C25 chains. As chain length increases ultimately we reach polyethylene, which consists of carbon chains of indefinite length, which is generally a hard white solid. Chemical properties[ edit ] Alkanes react only very poorly with ionic or other polar substances. The pKa values of all alkanes are above 50, and so they are practically inert to acids and bases. This inertness is the source of the term paraffins (Latin para + affinis, with the meaning here of "lacking affinity"). In crude oil 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 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. 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 highly branched alkanes and cycloalkanes, the bond angles 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 hinderance, and can substantially increase the reactivity. The same is preferred for alkenes too. Introduction to Nomenclature[ edit ] Before we can understand reactions in organic chemistry, we must begin with a basic knowledge of naming the compounds.

The IUPAC nomenclature is a system on which most organic chemists have agreed to provide guidelines to allow them to learn from each others' works. Nomenclature, in other words, provides a foundation of language for organic chemistry. The names of all alkanes end with -ane. Whether or not the carbons are linked together end-to-end in a ring (called cyclic alkanes or cycloalkanes) or whether they contain side chains and branches, the name of every carbon-hydrogen chain that lacks any double bonds or functional groups will end with the suffix -ane. Alkanes with unbranched carbon chains are simply named by the number of carbons in the chain. The first four members of the series (in terms of number of carbon atoms) are named as follows: CH4 = methane = one hydrogen-saturated carbon C2H6 = ethane = two hydrogen-saturated carbons C3H8 = propane = three hydrogen-saturated carbons C4H10 = butane = four hydrogen-saturated carbons Alkanes with five or more carbon atoms are named by adding the suffix -ane to the appropriate numerical multiplier, except the terminal -a is removed from the basic numerical term.

Hence, C5H12 is called pentane, C6H14 is called hexane, C7H16 is called heptane and so forth. Straight-chain alkanes are sometimes indicated by the prefix n- (for normal) to distinguish them from branched-chain alkanes having the same number of carbon atoms. 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 is a neurotoxin while its branched-chain isomers are not. Number of hydrogens to carbons[ edit ] This equation describes the relationship between the number of hydrogen and carbon atoms in alkanes: H = 2C + 2 where "C" and "H" are used to represent the number of carbon and hydrogen atoms present in one molecule. If C = 2, then H = 6. Many textbooks put this in the following format: CnH2n+2 where "Cn" and "H2n+2" represent the number of carbon and hydrogen atoms present in one molecule.

If Cn = 3, then H2n+2 = 2(3) + 2 = 8. (For this formula look to the "n" for the number, the "C" and the "H" letters themselves do not change.) Progressively longer hydrocarbon chains can be made and are named systematically, depending on the number of carbons in the longest chain. Naming carbon chains up to twelve[ edit ] methane (1 carbon) undecane (11 carbons) dodecane (12 carbons) The prefixes of the first three are the contribution of a German Chemist, August Wilhelm Hoffman, who also suggested the name quartane for 4 carbons in 1866. However, the but- prefix had already been in use since the 1820s and the name quartane never caught on. He also recommended the endings to use the vowels, a, e, i (or y), o, and u, or -ane, -ene, -ine or -yne, -one, and -une. Again, only the first three caught on for single, double, and triple bonds and -one was already in use for ketones.

Pent, hex, hept, oct, and dec all come from the ancient Greek numbers (penta, hex, hepta, octa, deka) and oddly, non, from the Latin novem. For longer-chained alkanes we use the special IUPAC multiplying affixes. For example, pentadecane signifies an alkane with 5+10 = 15 carbon atoms. For chains of length 30, 40, 50, and so on the basic prefix is added to -contane. For example, C57H116 is named as heptapentacontane. When the chain contains 20-29 atoms we have an exception. C20H42 is known as icosane, and then we have, e.g. tetracosane (eliding the "i" when necessary). For the length 100 we have "hecta" but for 200, 300 ...

900 we have "dicta", "tricta", and so on, eliding the "i" on "icta" when necessary; for 1000 we have "kilia" but for 2000 and so on, "dilia", "trilia", and so on, eliding the "i" on "ilia" when necessary. We then put all of the prefixes together in reverse order. The alkane with 9236 carbon atoms is then hexatridinoniliane. Isomerism[ edit ] The atoms in alkanes with more than three carbon atoms can be arranged in many ways, leading to a large number of potential different configurations (isomers). So-called "normal" alkanes have a linear, unbranched configuration, but the n- isomer of any given alkane is only one of potentially hundreds or even possibly millions of configurations for that number of carbon and hydrogen atoms in some sort of chain arrangement. Isomerism is defined as the compound having same moleculer formula the formula which present the different moleculer formula arrangement are called as Isomerism. e.g.- The molecular formula for butane is C4H10.

The number of isomers increases rapidly with the number of carbon atoms in a given alkane molecule; for alkanes with as few as 12 carbon atoms, there are over three hundred and fifty-five possible forms the molecule can take! # Carbon Atoms Branched chains[ edit ] Carbon is able to bond in all four directions and easily forms strong bonds with other carbon atoms. When one carbon is bonded to more than two other carbons it forms a branch. Isobutane Neopentane Above you see a carbon bonded to three and four other carbons. Note: a methane group is called a methyl group when it is bonded to another carbon instead of a fourth hydrogen. –CH3 The common system has naming convention for carbon chains as they relate to branching. n-alkanes are linear iso-alkanes have one branch R2CH— neo-alkanes have two branches R3C— Note: "R" in organic chemistry is a placeholder that can represent any carbon group. Constitutional isomers[ edit ] One of the most important characteristics of carbon is its ability to form several relatively strong bonds per atom.

It is for this reason that many scientists believe that carbon is the only element that could be the basis for the many complicated molecules needed to support a living being. One carbon atom can have attached to it not just the one or two other carbons needed to form a single chain but can bond to up to four other carbons. It is this ability to bond multiply that allows isomerism. Isomers are two molecules with the same molecular formula but different physical arrangements. Constitutional isomers have their atoms arranged in a different order. A constitutional isomer of butane has a main chain that is forked at the end and one carbon shorter in its main chain than butane. Butane Naming Alkanes[ edit ] There are several ways or systems for the nomenclature, or naming, of organic molecules, but just two main ones. The traditional, non-systematic names. Many of these linger on, especially for simpler or more common molecules. The systematic IUPAC (eye-YOU-pack (International Union of Pure And Applied Chemistry)) names. The IUPAC system is necessary for complicated organic compounds. It gives a series of unified rules for naming a large compound by conceptually dividing it up into smaller, more manageable nameable units.

Many traditional (non-IUPAC) names are still commonly used in industry, especially for simpler and more common chemicals, as the traditional names were already entrenched. IUPAC naming rules[ edit ] Naming branched substituents[ edit ] 3-(1-methylethyl)-2,4-dimethylpentane The main chain in the drawing is numbered 1-5. The main part of the branched substituent, an ethyl group, is numbered 1' and 2'. The methyl substituent off of the ethyl substituent is not numbered in the drawing. To name the compound, put the whole branched substituent name in parentheses and then number and alphabetize as if a simple substituent. Common system[ edit ] Some prefixes from the common system are accepted in the IUPAC system. For alphabetization purposes, iso- and neo- are considered part of the name, and alphabetized. Sec- and tert- are not considered an alphabetizable part of the name. (In the following images, the R- represents any carbon structure.) Iso-[ edit ] Iso- can be used for substituents that branch at the second-to-last carbon and end with two methyls.

An isobutyl has four carbons total: Isobutyl Methane Myopia: 1 – Political Science | MalagaBay Methane Myopia: 1 – Political Science Posted on November 9, 2013 by malagabay Methane is a political gas [just like Carbon Dioxide and Ozone] that generates significant revenue for mainstream post-normal science. Methane is a chemical compound with the chemical formula CH4 (one atom of carbon and four atoms of hydrogen). It is the simplest alkane and the main component of natural gas. The relative abundance of methane makes it an attractive fuel. However, because it is a gas at normal conditions, methane is difficult to transport from its source. Methane clathrate (CH4•5.75H2O), also called methane hydrate, hydromethane, methane ice, fire ice, natural gas hydrate, or gas hydrate, is a solid clathrate compound (more specifically, a clathrate hydrate) in which a large amount of methane is trapped within a crystal structure of water, forming a solid similar to ice. Global warming evangelists have especially demonised methane gas as a “potent greenhouse gas”.

Atmospheric methane is a potent greenhouse gas (per unit, more so than carbon dioxide). The concentration of methane in Earth’s atmosphere in 1998, expressed as a mole fraction, was 1745 nmol/mol (parts per billion, ppb). By 2008, however, global methane levels, which had stayed mostly flat since 1998, had risen to 1800 nmol/mol. Unfortunately, the science of greenhouse gases [and atmospheric chemistry] is seriously compromised. Take, for example, the following [jumbled] scientific rant about methane by Wikipedia. Some gases have indirect radiative effects (whether or not they are a greenhouse gas themselves). This happens in two main ways. One way is that when they break down in the atmosphere they produce another greenhouse gas. For example methane and carbon monoxide (CO) are oxidized to give carbon dioxide (and methane oxidation also produces water vapor; that will be considered below). … Methane has a number of indirect effects in addition to forming CO2. Firstly, the main chemical which destroys methane in the atmosphere is the hydroxyl radical (OH).

Methane reacts with OH and so more methane means that the concentration of OH goes down. Effectively, methane increases its own atmospheric lifetime and therefore its overall radiative effect. The second effect is that the oxidation of methane can produce ozone. Thirdly, as well as making CO2 the oxidation of methane produces water; this is a major source of water vapor in the stratosphere which is otherwise very dry. CO and NMVOC also produce CO2 when they are oxidized. They remove OH from the atmosphere and this leads to higher concentrations of methane. The surprising effect of this is that the global warming potential of CO is three times that of CO2. The same process that converts NMVOC to carbon dioxide can also lead to the formation of tropospheric ozone. Halocarbons have an indirect effect because they destroy stratospheric ozone. Finally hydrogen can lead to ozone production and CH4 increases as well as producing water vapor in the stratosphere. Superficially, the Wikipedia science appears plausible. Unfortunately, atmospheric chemistry isn’t that straight forward because atmospheric molecules are continuously being broken down [into component elements and/or molecules] by photodissociation.

The resultant component molecules may then [in turn] be broken down by photodissociation or they may recombine with other elements [and/or molecules] to form other molecules. These recombined molecules are then recycled through the same process by photodissociation. Thus, atmospheric chemistry is based upon the continual recycling [churning] of molecules and elements via photodissociation and recombination. Additionally, the churning mechanism is randomised because photodissociation is driven by photon absorption and recombination is determined by collision. Basically, atmospheric chemistry is a numbers game [which operates rather like a casino] where the outcome of any one event is driven by chance while collectively the outcome of many events should be statistically predictable [although this has not been demonstrated by atmospheric “science”]. With that basic understanding of atmospheric chemistry let’s return to the demon methane and look at the methane oxidation cycle that humans have constructed from the random churning in the atmosphere. Figure 6: Schematic of the CH4 oxidation cycle (from Wayne, 1991).

The bold arrows in the first half of the cycle indicate what happens without NOx, while the thin arrows on the second half indicate processes that require NOx, and close the loop back to the formation of hydroxyl. In summary, NOx plays a very important role in the methane oxidation cycle. If it is sufficiently abundant, it closes the loop of a cycle that regenerates hydroxyl. In its absence, the cycle terminates abruptly and methane becomes a sink for hydroxyl. Methane and Carbon Monoxide in the Troposphere Oxidation Steps for CO and CH4 Hydroxyl radicals formed in reaction (8.2) react mainly with CO and CH4 OH + CO -> CO2 OH + CH4 -> CH3 + H2O Roughly 70 per cent of the OH reacts with CO, and 30 per cent with CH4, in the unpolluted atmosphere. Atmospheric Chemistry – A M Holloway and R P Wayne – 2010 Strangely, the initial Wikipedia claim that “methane and carbon monoxide (CO) are oxidized to give carbon dioxide” is not directly supported by the methane oxidation schematic.

However, with a bit of cherry picking and conjuring from the churning soup of atmospheric chemistry it is probably possible to construct some chain of events that connects methane to carbon dioxide. Wikipedia then goes on to state: “Methane reacts with OH and so more methane means that the concentration of OH goes down.” However, this is really a red herring because the level of OH in the atmosphere is primarily determined by the level of water vapour in the atmosphere because the photodissociation of H2O produces O and OH. Intriguing, the inconvenient photodissociation of water vapour in the Earth’s atmosphere has become very unfashionable with post-normal science because it disrupts their carefully constructed settled science regarding ozone, carbon dioxide and methane. Thus, Wikipedia has banished the photodissociation of water vapour [and methane] from Earth and confined the process to the “interstellar medium”. Next up from Wikipedia we have: “the oxidation of methane can produce ozone”. Unsurprisingly, the methane oxidation schematic shows the exact opposite because the diagram associates the production of OH with the photodissociation [destruction] of O3 [ozone].

However, [again] with a bit of cherry picking and conjuring from the churning soup of atmospheric chemistry it is probably possible to construct some chain of events that connects methane to ozone production. Although, it is just as possible that Wikipedia really means destroys when it says “produce” because the mainstream has a problem with ozone depletion [but that’s another sad story for another day]. Wikipedia then follows up with “the oxidation of methane produces water”. This [surprisingly] is a correct statement supported by the methane oxidation schematic. However, [unsurprisingly] this is really only a problem for the believers in global warming because water vapour in the atmosphere has a nasty habit of forming clouds which have a devious tendency to block incoming solar radiation and, thus, fiendishly cools the Earth’s surface. Wikipedia closes its indictment of methane with the following statement: “Finally hydrogen can lead to ozone production and CH4 increases as well as producing water vapor in the stratosphere.” This is really a gem of twisting, turning and circular logic which appears to be demonizing the evil hydrogen without directly mentioning the [banished] photodissociation of H2O into H and OH.

Indeed, the photodissociation of water molecules liberates hydrogen atoms which may then recombine [possibly after forming H2] with a single carbon atom [possibly liberated by the photodissociation of CO or CO2 (such irony)] to form methane [CH4]. However, the subsequent oxidation [of the thus formed methane] neutralises the process because the oxidation of methane is associated with the production of water [as correctly stated by Wikipedia]. Note: The subsequent photodissociation of the liberated OH will liberate O and H atoms. The liberated H atom may [or may not] join the CH4 recombination party. The liberated O atom may [or may not] join the O3 recombination party. Overall, the settled science presented by Wikipedia indicates that methane is not an indictable indirect greenhouse gas because the oxidation of methane produces water vapour which forms clouds that prevent incoming solar radiation from warming the surface of the Earth. To be continued… UPDATE 12 Nov 2013 One of the dodges employed by the mainstream is to combine [old fashioned] oxidation with [old fashioned] combustion into a [far more fashionable] definition: Redox reactions.

Redox Thus, when an [modern] “environmentalists” refers to methane oxidation they may actually be referring to methane combustion [or vice versa]. Wikipedia [very helpfully] provides an overview of “part of the process” they have bolted together for methane combustion. Unsurprisingly, Wikipedia hasn’t provided a flow chart that actually defines the chain of events that supports [defines] the claimed “net result”: CH4 + 2 O2 → CO2 + 2 H2O Instead, Wikipedia provides five oxidation reactions involving CH4 [see 1,2,3,4 and 6 above] where: a) Only one of the equations [see 4 above] produces a molecule of H2O. b) None of the equations produce any CO2. The claimed chain of events, therefore, probably follows the CH3 molecule that is produced by all five of CH4 oxidation reactions [see 1,2,3,4 and 6 above]. However, CH3 is “highly reactive and rarely observed” and the likelihood is that the CH3 molecule will react with the first random molecule [or element] that it bumps into.

A methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms — CH3. The group is often abbreviated Me. Such hydrocarbon groups occur in many organic compounds. While the methyl group is usually part of a larger molecule, it can be found on its own in either of three forms: anion, cation or radical. The anion has eight valence electrons, the radical seven and the cation six. All three forms are highly reactive and rarely observed. The Rabbett Run blog has constructed a chain of events that links CH4 to one molecule of CO2 [via CH3]. Passing Gas – Rabbet Run – February 04, 2010 However, this “event chain”: i) May rarely occur given the reactive nature of CH3 and the availability of other atoms and molecules in the atmosphere i.e. it may be possible but there is no guarantee that it is even probable. ii) May be broken at any point by random photodissociation, recombination, ionization, electron capture, combustion and collision with another atom / molecule / particle [that is not in the involved in the defined event chain].

iii) Does not have the claimed “end result” because atmospheric chemistry is a continuous process [it never stops] and the claimed “end result” is instantly subject to random photodissociation, recombination, ionization, electron capture, combustion and collision with another atom / molecule / particle. iv) Is a human construct that does not accurately reflect reality because “event chains” are not preordained and they are not executed in isolation in the atmosphere. UPDATE 13 Nov 2013 There is a really delicious irony [tucked away in the Methane section of Wikipedia] that claims that naturally occurring methane is mainly produced biologically by a chemical reaction that converts CO2 into CH4 and water [with some help from ionised hydrogen and some electrons]. Thus, it appears, the biosphere is busy converting CO2 into CH4 so mankind can burn the methane gas and, thereby, convert the CH4 back into CO2. This appears to be a very sustainable natural cycle which is very beneficial to mankind because we can use the energy from combustion and enjoy the water liberated by both chemical reactions. I am sure the “environmentalists” are just going to hate the concept.

Abraham Lake, Alberta, Canada Temperatures may fall below -30 degrees Celsius here, thus making this big lake freeze. The unique circles are frozen bubbles of methane gas, coming from the depth. This creates the unusual phenomena, which looks so incredible in winter. Methane (CH4) Methane (CH4) Methane (CH4) Methane is a chemical compound with the molecular formula CH4. It is the simplest alkane, and the principal component of natural gas. Methane's bond angles are 109.5 degrees. Burning methane in the presence of oxygen produces carbon dioxide and water. The relative abundance of methane and its clean burning process makes it a very attractive fuel. However, because it is a gas at normal temperature and pressure, methane is difficult to transport from its source. In its natural gas form, it is generally transported in bulk by pipeline or LNG carriers; few countries still transport it by truck. Methane is a relatively potent greenhouse gas with a high global warming potential of 72 (averaged over 20 years) or 25 (averaged over 100 years). Methane in the atmosphere is eventually oxidized, producing carbon dioxide and water.

As a result, methane in the atmosphere has a half life of seven years (if no methane were added, then every seven years, the amount of methane would halve). The abundance of methane in the Earth's atmosphere in 1998 was 1745 parts per billion, up from 700 ppb in 1750. In the same time period, CO2 increased from 278 to 365 parts per million. The radiative forcing effect due to this increase in methane abundance is about one-third of that of the CO2 increase. In addition, there is a large, but unknown, amount of methane in methane clathrates in the ocean floors. The Earth's crust contains huge amounts of methane. Large amounts of methane are produced anaerobically by methanogenesis. Other sources include mud volcanoes, which are connected with deep geological faults, and livestock (primarily cows) from enteric fermentation. Methane is a significant contributor to global warming and the Kyoto protocol seeks to regulate its production. Properties Methane is the major component of natural gas, about 87% by volume.

At room temperature and standard pressure, methane is a colorless, odorless gas; the smell characteristic of natural gas as used in homes is an artificial safety measure caused by the addition of an odorant, often methanethiol or ethanethiol. Methane has a boiling point of −161 �C at a pressure of one atmosphere. As a gas it is flammable only over a narrow range of concentrations (5�15%) in air. Liquid methane does not burn unless subjected to high pressure (normally 4�5 atmospheres). Potential health effects Methane is not toxic; however, it is highly flammable and may form explosive mixtures with air. Methane is violently reactive with oxidizers, halogens, and some halogen-containing compounds. Methane is also an asphyxiant and may displace oxygen in an enclosed space. Asphyxia may result if the oxygen concentration is reduced to below 19.5% by displacement. The concentrations at which flammable or explosive mixtures form are much lower than the concentration at which asphyxiation risk is significant.

When structures are built on or near landfills, methane off-gas can penetrate the buildings' interiors and expose occupants to significant levels of methane. Some buildings have specially engineered recovery systems below their basements to actively capture such fugitive off-gas and vent it away from the building. An example of this type of system is in the Dakin Building, Brisbane, California. Reactions of methane Main reactions with methane are: combustion, steam reforming to syngas, and halogenation. In general, methane reactions are hard to control. Partial oxidation to methanol, for example, is difficult to achieve; the reaction typically progresses all the way to carbon dioxide and water. Combustion In the combustion of methane, several steps are involved: Methane is believed to form a formaldehyde (HCHO or H2CO). The formaldehyde gives a formyl radical (HCO), which then forms carbon monoxide (CO). The process is called oxidative pyrolysis: CH4 + O2 → CO + H2 + H2O Following oxidative pyrolysis, the H2 oxidizes, forming H2O, replenishing the active species, and releasing heat. This occurs very quickly, usually in significantly less than a millisecond.

2H2 + O2 →2H2O Finally, the CO oxidizes, forming CO2 and releasing more heat. This process is generally slower than the other chemical steps, and typically requires a few to several milliseconds to occur. 2CO + O2 →2CO2 The result of the above is the following total equation: CH4(g) + 2O2(g) → CO2(g) + 2H2O(l) + 890 kJ/mol where bracketed "g" stands for gaseous form and bracketed "l" stands for liquid form. Hydrogen activation The strength of the carbon-hydrogen covalent bond in methane is among the strongest in all hydrocarbons, and thus its use as a chemical feedstock is limited. Despite the high activation barrier for breaking the C�H bond, CH4 is still the principal starting material for manufacture of hydrogen in steam reforming. The search for catalysts which can facilitate C�H bond activation in methane and other low alkanes is an area of research with considerable industrial significance.

Reactions with halogens Methane reacts with all halogens given appropriate conditions, as follows: CH4 + X2 → CH3X + HX where X is a halogen: fluorine (F), chlorine (Cl), bromine (Br), or iodine (I). This mechanism for this process is called free radical halogenation. Uses Fuel Methane is important for electrical generation by burning it as a fuel in a gas turbine or steam boiler. Compared to other hydrocarbon fuels, burning methane produces less carbon dioxide for each unit of heat released. At about 891 kJ/mol, methane's combustion heat is lower than any other hydrocarbon; but a ratio with the molecular mass (16.0 g/mol) divided by the heat of combustion (891 kJ/mol) shows that methane, being the simplest hydrocarbon, produces more heat per mass unit than other complex hydrocarbons. In many cities, methane is piped into homes for domestic heating and cooking purposes. In this context it is usually known as natural gas, and is considered to have an energy content of 39 megajoules per cubic meter, or 1,000 BTU per standard cubic foot.

Methane in the form of compressed natural gas is used as a vehicle fuel, and is claimed to be more environmentally friendly than fossil fuels such as gasoline/petrol and diesel. Research is being conducted by NASA on methane's potential as a rocket fuel. One advantage of methane is that it is abundant in many parts of the solar system and it could potentially be harvested in situ , providing fuel for a return journey. Current methane engines in development produce a thrust of 7,500 pounds , which is far from the seven million pounds needed to launch the space shuttle. Instead, such engines will most likely propel voyages from our moon or send robotic expeditions to other planets in the solar system. Recently methane emitted from coal mines has been successfully converted to electricity. Industrial uses Methane is used in industrial chemical processes and may be transported as a refrigerated liquid (liquefied natural gas, or LNG). While leaks from a refrigerated liquid container are initially heavier than air due to the increased density of the cold gas, the gas at ambient temperature is lighter than air. Gas pipelines distribute large amounts of natural gas, of which methane is the principal component.

In the chemical industry, methane is the feedstock of choice for the production of hydrogen, methanol, acetic acid, and acetic anhydride. When used to produce any of these chemicals, methane is first converted to synthesis gas, a mixture of carbon monoxide and hydrogen, by steam reforming. In this process, methane and steam react on a nickel catalyst at high temperatures (700�1100 �C). The ratio of carbon monoxide to hydrogen in synthesis gas can then be adjusted via the water gas shift reaction to the appropriate value for the intended purpose. CO + H2O → CO2 + H2 Less significant methane-derived chemicals include acetylene, prepared by passing methane through an electric arc, and the chloromethanes (chloromethane, dichloromethane, chloroform, and carbon tetrachloride), produced by reacting methane with chlorine gas. However, the use of these chemicals is declining. Acetylene is replaced by less costly substitutes, and the use of chloromethanes is diminishing due to health and environmental concerns. Sources of methane Natural gas fields The major source of methane is extraction from geological deposits known as natural gas fields.

It is associated with other hydrocarbon fuels and sometimes accompanied by helium and nitrogen. The gas at shallow levels (low pressure) is formed by anaerobic decay of organic matter and reworked methane from deep under the Earth's surface. In general, sediments buried deeper and at higher temperatures than those which give oil generate natural gas. Methane is also produced in considerable quantities from the decaying organic wastes of solid waste landfills. Alternative sources Apart from gas fields, an alternative method of obtaining methane is via biogas generated by the fermentation of organic matter including manure, wastewater sludge, municipal solid waste (including landfills), or any other biodegradable feedstock, under anaerobic conditions. Methane hydrates/clathrates (icelike combinations of methane and water on the sea floor, found in vast quantities) are a potential future source of methane. Cattle belch methane accounts for 16% of the world's annual methane emissions to the atmosphere. The livestock sector in general (primarily cattle, chickens, and pigs) produces 37% of all human-induced methane". However animals "that put their energies into making gas are less efficient at producing milk and meat".

Early research has found a number of medical treatments and dietary adjustments that help limit the production of methane in ruminants. Industrially, methane can be created from common atmospheric gases and hydrogen (produced, for example, by electrolysis) through chemical reactions such as the Sabatier process, Fischer-Tropsch process. Coal bed methane extraction is a method for extracting methane from a coal deposit, while enhanced coal bed methane recovery is a method of recovering methane from an unminable coal seam. Scientific experiments have given variable results in determining whether plants are a source of methane emissions. Methane in Earth's atmosphere Early in the Earth's history�about 3.5 billion years ago�there was 1,000 times as much methane in the atmosphere as there is now. The earliest methane was released into the atmosphere by volcanic activity. During this time, Earth's earliest life appeared. These first, ancient bacteria added to the methane concentration by converting hydrogen and carbon dioxide into methane and water. Oxygen did not become a major part of the atmosphere until photosynthetic organisms evolved later in Earth's history. With no oxygen, methane stayed in the atmosphere longer and at higher concentrations than it does today.

In present times, due to the increase in oxygen, the amount of methane has decreased. The average mole concentration of methane at the Earth's surface in 1998 was 1,745 ppb. Its concentration is higher in the northern hemisphere as most sources (both natural and human) are larger. The concentrations vary seasonally with a minimum in the late summer mainly due to removal by the hydroxyl radical. Methane is created near the surface, and it is carried into the stratosphere by rising air in the tropics. Uncontrolled build-up of methane in Earth's atmosphere is naturally checked�although human influence can upset this natural regulation�by methane's reaction with hydroxyl radicals formed from singlet oxygen atoms and with water vapor. Methane as a greenhouse gas Methane in the Earth's atmosphere is an important greenhouse gas with a global warming potential of 25 Kg CO2e over a 100-year period. This means that a methane emission will have 21 times the impact on temperature of a carbon dioxide emission of the same mass over the following 100 years.

Methane has a large effect for a brief period (a net lifetime of 8.4 years in the atmosphere), whereas carbon dioxide has a small effect for a long period (over 100 years). Because of this difference in effect and time period, the global warming potential of methane over a 20 year time period is 72. The Earth's methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases. Usually, excess methane from landfills and other natural producers of methane are burned so CO2 is released into the atmosphere instead of methane because methane is such a more effective greenhouse gas. Recently methane emitted from coal mines has been successfully converted to electricity. Megtec Systems Inc. developed a patented combination of emission control and steam cycle technologies, the VOCSIDIZER which has been converting the energy of the coal mine�s 0.9% VAM concentration into electrical power. Emissions accounting of methane The balance between sources and sinks is not yet fully understood.

The IPCC Working Group 1 stated in chapter 2 of the Fourth Assessment Report that there are "large uncertainties in the current bottom-up estimates of components of the global source", and the balance between sources and sinks is not yet well known. The most important sink in the methane cycle is reaction with the hydroxyl radical, which is produced photochemically in the atmosphere. Production of this radical is not fully understood and has a large affect on atmospheric concentrations. This uncertainty is exemplified by observations that have shown between the year 2000 and 2006 increases in atmospheric concentration of methane ceased without reduction in anthropogenic sources, showing that methane accounting does not accurately predict methane observations. Origin +7.19 ppb/a Slightly over half of the total emission is due to human activity. Living plants (e.g. forests) have recently been identified as a potentially important source of methane. A 2006 paper calculated emissions of 62�236 Tg a-1, and "this newly identified source may have important implications". However the authors stress "our findings are preliminary with regard to the methane emission strength".

These findings have been called into question in a 2007 paper which found "there is no evidence for substantial aerobic methane emission by terrestrial plants, maximally 0.3% of the previously published values". Long term atmospheric measurements of methane by NOAA show that the build up of methane has slowed dramatically over the last decade, after nearly tripling since pre-industrial times. It is thought that this reduction is due to reduced industrial emissions and drought in wetland areas. Very recent data now suggests that methane concentrations may be rising again. Removal processes The major removal mechanism of methane from the atmosphere involves radical chemistry; it reacts with the hydroxyl radical (�OH), initially formed from water vapor broken down by oxygen atoms that come from the cleavage of ozone by ultraviolet radiation: CH4 + �OH → �CH3 + H2O This reaction in the troposphere gives a methane lifetime of 9.6 years. Two more minor sinks are soil sinks (160 year lifetime) and stratospheric loss by reaction with �OH, �Cl and �O1D in the stratosphere (120 year lifetime), giving a net lifetime of 8.4 years.

Oxidation of methane is the main source of water vapor in the upper stratosphere (beginning at pressure levels around 10 kPa). The methyl radical formed in the above reaction will, during normal daytime conditions in the troposphere, usually react with another hydroxyl radical to form formaldehyde. Note that this is not strictly oxidative pyrolysis as described previously. Formaldehyde can react again with a hydroxyl radical to form carbon dioxide and more water vapor. Note that sidechains in these reactions may interact with nitrogen compounds that will likely produce ozone, thus supplanting radicals required in the initial reaction. Sudden release from methane clathrates At high pressures, such as are found on the bottom of the ocean, methane forms a solid clathrate with water, known as methane hydrate. An unknown, but possibly very large quantity of methane is trapped in this form in ocean sediments. The sudden release of large volumes of methane from such sediments into the atmosphere has been suggested as a possible cause for rapid global warming events in the Earth's distant past, such as the Paleocene�Eocene Thermal Maximum of 55 million years ago, and the Great Dying.

Theories suggest that should global warming cause them to heat up sufficiently, all of this methane could again be suddenly released into the atmosphere. Since methane is twenty-five times stronger (for a given weight, averaged over 100 years) than CO2 as a greenhouse gas; this would immensely magnify the greenhouse effect, heating Earth to unprecedented levels. Release of methane from bogs Although less dramatic than release from clathrates, but already happening, is an increase in the release of methane from bogs as permafrost melts. Although records of permafrost are limited, recent years (1999 to 2007) have seen record thawing of permafrost in Alaska and Siberia. Recent measurements in Siberia show that the methane released is five times greater than previously estimated. Extraterrestrial methane Methane has been detected or is believed to exist in several locations of the solar system. It is believed to have been created by abiotic processes, with the possible exception of Mars. Moon - traces are present in the thin atmosphere Mars - the atmosphere contains 10 ppb methane.

In January 2009, NASA scientists announced that they had discovered that the planet regularly vents methane into the atmosphere in specific areas at regular times, leading some to speculate this may be a sign of biological activity going on below the surface. Jupiter - the atmosphere contains about 0.3% methane Saturn - the atmosphere contains about 0.4% methane Iapetus

Question: What chemical compound of 1 carbon and 4 hydrogen atoms is the simplest alkane, and the principal component of natural gas?
Answer: Methane