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Alkanes

Alkanes are hydrocarbons in which the carbon atoms are held together by single bonds.  Their general formula is CnH2n+2 for molecules which do not contain ring structures.

Alkanes are in some respect the most boring of the organic compounds, since they are unreactive (mostly) towards acids, bases, oxidizing agents, reducing agents, and most of the other reagents that organic chemists have in their arsenals.  On the other hand, alkanes are important for their ability to undergo combustion with molecular oxygen (O2):  alkanes of various lengths are the major components of the hydrocarbon fuels that we burn for energy, whether for cooking (methane, propane, butane) or for transportation (gasoline, diesel fuels):

CnH2n+2  +  (3n+1)/2O2    nCO2  +  (n+1)H2O  +  energy

 

 

Straight-Chain and Branched Alkanes

The straight-chain (normal) and branched alkanes have the general formula CnH2n+2.  The molecules consist of either straight chains of carbon atoms, connected one after the other, with the appropriate number of hydrogen atoms on each carbon, or as branched chains of carbon atoms having carbon substituents (alkyl groups) attached at various points along the chain.

Straight-chain alkanes are named by using a stem that indicates the number of carbon atoms (meth = 1 C, eth = 2 C's, prop = 3 C's, etc.) to which is added the suffix -ane, indicating that the molecule is an alkane (that is, that the carbon atoms are all connected by single bonds).  Thus, the word "propane" indicates that there are three carbon atoms in the chain, all connected by single bonds.

Number of
Carbons
Stem
1 meth-
2 eth-
3 prop-
4 but-
5 pent-
6 hex-
7 hept-
8 oct-
9 non-
10 dec-

For branched chains, the name of the longest continuous chain of carbon atoms is preceded by the names of the carbon substituents, which are named as alkyl groups (#C prefix + -yl); a position number is placed in front of the alkyl group name to indicate which carbon of the longest chain the alkyl group is attached to. If there is more than one of the same type of alkyl group, their names are combines into a single word, prefixed by a counting prefix (2 = di, 3 = tri, 4 = tetra, 5 = penta, etc.), and preceded by location numbers for each group.  Thus, the name "2-methylpropane" indicated that there is a three-carbon longest chain, with a one-carbon branch on the second carbon; the name "2,3-dimethylbutane" indicates that there is a four-carbon longest chain, with two one-carbon substituents on carbons 2 and 3.

Some molecules of the same molecular formula can have their atoms arranged in a different order; we say that these molecules are structural isomers of each other.  The simplest alkanes have only one way in which their atoms can be arranged, and have no structural isomers.  As the number of carbon atoms increases, the number of structural isomers increases rapidly (see butane and isobutane below for examples).

The carbon atoms in alkanes are sp3-hybridized, and have tetrahedral shapes, with the bonded atoms at angles of 109.5 to each other.  Free rotation is possible around the carbon-carbon single bonds in alkanes, making the carbon chains very flexible and "floppy" — particularly for the larger molecules.

Alkanes are nonpolar molecules, since they contain only nonpolar carbon-carbon and carbon-hydrogen bonds.  They are therefore not soluble in water, and since they are generally less dense than water, they will float on water (e.g., oil slicks).  The only intermolecular forces acting between alkane molecules are very weak London forces (also known as dispersion forces) which result from the attractions between instantaneous dipoles formed as a result of random fluctuations of electrons in nonpolar molecules.  As the number of carbon atoms increases, the attractions due to these weak London forces increase, and the boiling point of the molecule increases.  (See Table 1 below.)  The lower-molecular mass alkanes (1 to 4 carbons) are gases at room temperature, those having 5 to 20 carbons tend to be liquids with increasingly high boiling points, and those with more than 20 carbons are increasingly viscous liquids, and finally waxy solids at room temperature.  (In the words of Stephen Wright, "It doesn't matter what temperature a room is, it's always room temperature.")

The low-molecular mass alkanes, from 1 to 4 carbons, are frequently used as cooking fuels; molecules of intermediate length (6-12 carbons) are found in gasoline and diesel fuels; longer carbon chains are found in motor oils, lubricants, emollients, greases, waxes, paraffin, and other applications.  Many of these compounds are isolated from petroleum, and may serve as the starting points for the synthesis of more complex molecules.

Methane, CH4 3D

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Methane is an odorless, nontoxic, flammable gas, which has a boiling point of -164.0C.  It is produced by the bacterial decomposition of organisms in the absence of oxygen, and is found in natural gas, marsh gas, bovine flatulence, etc.  Natural gas is about 70%-95% methane depending on the location in which it is obtained.  It burns cleanly, and so is useful in cooking.  Ethanethiol is added to natural gas to give it an unpleasant odor, thereby making gas leaks detectable.

 
   
Ethane, CH3CH3 (C2H6) 3D

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Ethane is an odorless, nontoxic, flammable gas, which has a boiling point of -88.6C.  It is a minor component of natural gas (10%-30%, depending on the location of the source).

 
   
Propane, CH3CH2CH3 (C3H8) 3D

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Propane is used as an industrial fuel, and in home heating and cooking.  Both propane and butane are used as LPG fuels (liquefied petroleum gas) for outdoor cooking, either in camping stoves or outdoor gas barbecue grills.  Propane liquefies at -42.1C at atmospheric pressure.

 
   
Butane, CH3CH2CH2CH3 (C4H10) 3D

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Butane, like propane, burns cleanly, and is used in LPG fuels (liquefied petroleum gas) for outdoor cooking.  Butane is a gas above -0.5C, but when slightly pressurized, forms a liquid.  In this form, it is used in cigarette lighters and lighter sticks.

 
   
2-Methylpropane (Isobutane) (C4H10) 3D

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Butane is an unbranched or "normal" alkane.  It is also possible to obtain a molecule with the formula C4H10 by having a chain of three carbons with a one-carbon branch (a methyl group) attached to the middle carbon.  This molecule is given the common ("trivial", i.e., non-systematic) name isobutane, and is more formally named as 2-methylpropane.  Butane and isobutane are structural isomers of each other, having the same molecular formula, but with the atoms connected in a different order.

This slight difference is enough to give butane and 2-methylpropane different physical properties:  for instance while butane boils at -0.5C, 2-methylpropane boils at a lower temperature, -11.7C.  (The lower boiling point is a result of the more compact structure of the 2-methylpropane isomer, which has less surface area than the straight-chain isomer, and thus fewer London forces between its molecules.)

 
   
Pentane, CH3CH2CH2CH2CH3 (C5H12) 3D

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Pentane is a liquid at room temperature, having a boiling point of 36.1C.  Notice that as the number of carbons increases, the boiling point also increases; this is a result of the longer carbon chains having more London forces acting between them.

 

There are three structural isomers of C5H12:


2-methylbutane
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2,2-dimethyl-propane
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Hexane, CH3CH2CH2CH2CH2CH3 (C6H14) 3D

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Hexane has a boiling point of 68.9C.  Mixtures of structural isomers of hexane are commonly used as organic solvents.

 

There are five structural isomers of C6H14:

Using common or non-systematic names is not practical for molecules with a large number of carbon atoms, since it would be necessary to memorize unique names for each possible compound.  (And as you can see in Table 1 below, the number of possible structural isomers increases drastically as more carbons are added!)  Systematic names, in which there is a one-to-one correspondence between the structure and the name, are a huge benefit to organic chemists.

 
   
Heptane, CH3(CH2)5CH3 (C7H16) 3D

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Heptane has a boiling point of 98.4C.  There are 9 structural isomers of C7H16.

 
   
Octane, CH3(CH2)6CH3 (C8H18) 3D

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Octane has a boiling point of 125.7C.  Eight carbons is typical for the size of the hydrocarbons present in gasoline.  There are 13 structural isomers of C8H18, one of which is isooctane (see below).

 
   
2,2,4-Trimethylpentane (Isooctane) 3D

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Isooctane is a structural isomer of octane (both are C8H18), but is branched (compare with butane and isobutane).  Branched alkanes tend to burn more smoothly than straight-chain alkanes when they are used in internal combustion engines.  Isooctane burns without knocking in a car’s engine; it is assigned an octane rating of 100, while heptane, which knocks badly, is assigned an octane rating of 0.  A fuel with an octane rating of 92 is equivalent in knocking characteristics to a fuel which is 92% isooctane and 8% heptane.

Tetraethyllead, Pb(CH2CH3)4, used to be widely used as an "anti-knocking" agent; this has been discontinued because of concerns about the release of lead into the atmosphere.  Other compounds can be used as antiknocking agents, such as MTBE (methyl tert-butyl ether — see the section on ethers for more information on this compound).

 
   
Nonane, CH3(CH2)7CH3 (C9H20) 3D

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Nonane has a boiling point of 150.8C.  There are 35 structural isomers of C9H20.

 
   
Decane, CH3(CH2)8CH3 (C10H22) 3D

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Decane has a boiling point of 174.1C.  There are 75 structural isomers of C10H22.

 
   
Hexadecane (Cetane), CH3(CH2)14CH3 (C16H34) 3D

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Hexadecane is typical for the number of carbons in the hydrocarbons present in diesel fuel.  In diesel fuels, straight chains are preferable to branched chains because fuel is sprayed into the cylinder during the power stroke, and needs to ignite as it enters.  Hexadecane is assigned a cetane number of 100, and the highly branched heptamethylnonane has a cetane number of 0.

 

 

 

Table 1.
S
ummary of the Straight-Chain Alkanes
Name Formula Melting
Point
(
C)
Boiling
Point
(
C)
Number of Structural
Isomers
Methane CH4 -182.5 -164.0 1
Ethane C2H6 -183.3 -88.6 1
Propane C3H8 -189.7 -42.1 1
Butane C4H10 -138.4 -0.5 2
Pentane C5H12 -129.7 36.1 3
Hexane C6H14 -95 68.9 5
Heptane C7H16 -90.6 98.4 9
Octane C8H18 -56.8 125.7 13
Nonane C9H20 -51 150.8 36
Decane C10H22 -29.7 174.1 75
Undecane C11H24 -25.6

195.9

 
Dodecane C12H26 -9.6

216.3

 
Tridecane C13H28      
Tetradecane C14H30      
Pentadecane C15H32      
Hexadecane C16H34      
Heptadecane C17H36      
Octadecane C18H38      
Nonadecane C19H40      
Eicosane C20H42 36.8

343.0

366,319 (!)
Heneicosane C21H44      
Docosane C22H46      
Tricosane C23H48      
Triacontane C30H62 66

449.7

4,111,846,763 (!!)
Hentriacontane C31H64      
Tetracontane C40H82     62,481,801,147,341 (!!!)
Pentacontane C50H102 92    
Hexacontane C60H122      
Heptacontane C70H142      
Octacontane C80H162      
Nonacontane C90H182      
Hectane C100H202      

Going beyond this would be reallyinsane.  (ha, ha)

 

 

 

Cycloalkanes

Cycloalkanes are alkanes in which the ends of the carbon chain are joined together, making a ring of carbon atoms (which requires the loss of two hydrogen atoms compared to the straight-chain alkanes).  They have the general formula CnH2n for molecules containing one ring.  (One Ring, of course, rules them all.)

Cycloalkanes are named in a similar fashion to straight-chain alkanes; the prefix cyclo- is added to the stem indicating the number of carbon atoms in the ring.  Carbon groups that are attached to the ring are named as alkyl groups.  Thus, the name "cyclobutane" indicates a ring of four carbon atoms, all linked by single bonds.

Free rotation is not possible around the carbon-carbon single bonds in rings, which leads to the introduction of stereoisomers — molecules having the same pattern of connectivity, but different arrangements of atoms in space.

Cyclopropane (C3H6) 3D


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Cyclopropane is a ring of three carbon atoms; the carbon atoms all lie within the same plane, at bond angles of 60 to each other.  This deviation from the ideal tetrahedral bond angles of 109.5 introduces a great deal of strain energy into the ring; consequently, cyclopropane rings are less stable, and rarer, than many other types of rings.  
Because free rotation is not possible around the single bonds in a cycloalkane, when two methyl groups are added to cyclopropane, there are two possible arrangements:  both methyl groups can be pointing to the same side of the ring (cis), or to opposite sides of the ring (trans):  

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These molecules are not structural isomers of each other, because the order in which the atoms are connected is the same, but the two methyl groups are pointing in different directions in space, making them stereoisomers of each other.  These types of stereoisomers are referred to as geometric isomers.

 
   
Cyclobutane (C4H8) 3D

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Cyclobutane is a ring of four carbon atoms; the carbon ring is not completely flat, and can buckle a little bit to relieve some of the eclipsing interactions of the C—H bonds; the bond angles are nearly 90, so there is still quite a bit of ring strain.  (As a molecule, it's not completely "square.")  Cyclobutanes are not very common in nature, but they are found in a few naturally occurring compounds.

 
   
Cyclopentane (C5H10) 3D

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Cyclopentane is a ring of five* carbon atoms.  The interior angles of a regular pentagon are 108, which is not very far from the ideal 109.5 bond angles of an alkane, so there is not a great deal of ring strain in this molecule.  The ring is able to "pucker" slightly to relieve some of the eclipsing interactions, and so all of the carbon atoms do not lie in the same plane.  Cyclopentanes are a more stable than cyclopropanes and cyclobutanes, and are found in wide variety of naturally occurring molecules.

*The phrase "ring of five" is one letter away from being a Johnny Cash song.

 
   
Cyclohexane (C6H12) 3D
 

With cyclohexane, ring chemistry gets even more interesting (and complicated).  Cyclohexane itself is a ring of six carbon atoms; if this were to form a perfect hexagon, the carbon-carbon bond angles would be 120 — a large deviation from ideal tetrahedral geometry.  However, cyclohexane can adopt one of two conformations which relieve this ring strain.  In one of these conformations, the carbon atoms on either side of the ring bend slightly upwards; in this so-called "boat" conformation, the bond angles all 109.5, relieving the ring strain.

 

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There are still a number of C—H eclipsing interactions, however, and this is not the lowest-energy conformation which is possible.  In the other possible conformation, one of the carbon atoms bends upwards, and the one on the opposite side bends downwards, producing the "chair" conformation; in this conformation, not only are the bond angles 109.5, but the eclipsing interactions are not present.  Cyclohexane rings are very stable, and are present in large numbers of naturally occurring molecules.

 

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(This is drastically oversimplified, of course; the chair and boat conformation represent the extremes of a large number of possible intermediate conformations, and the energetics of the ring system change a great deal when substituents are added to the ring.)

 
   
Cycloheptane (C7H14) 3D

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There is a slight amount of strain energy in cycloheptane and larger cycloalkanes, since it is difficult for them to adopt bond angles of 109.5 while still avoiding all eclipsing interactions.

 
   
Cyclooctane (C8H16) 3D

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Cyclooctane is a ring of eight carbon atoms.  This molecule is often found on traffic signs:

(well, maybe not)

 
   
Cyclononane (C9H18) 3D

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Cyclononane is a ring of nine carbon atoms.

 
   
Cyclodecane (C10H20) 3D

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Cyclodecane is a ring of ten carbon atoms.

 
   
Decalin (C10H18) 3D

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Decalin, or bicyclo[4.4.0]decane, is a bicyclic alkane, consisting of two rings fused together.  There are two geometric isomers of the molecule, the cis and trans form.

 

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Norbornane 3D

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Norbornane, bicyclo[2.2.1]heptane, is another bicyclic molecule, consisting of a six carbon ring whose opposite sides are held together by a bridging methylene (CH2) group.  Norbornane rings show up in a lot of interesting molecules, such as camphor.

 
   
Adamantane 3D

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Adamantane is a tricyclic molecule; the fused cyclohexane rings in this molecule are extremely rigid.  Extending the structure of adamantane further into three dimensions results in the structure of diamonds.

 
   
Cubane 3D

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Cubane was first synthesized by Philip Eaton and Thomas W. Cole at the University of Chicago in 1964.

 
   
Prismane 3D

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Prismane is so named because it looks like a molecular prism (duh).

 
   
Propellane 3D

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Propellane was first synthesized by K. B. Wiberg at Yale University.

 
   
Dodecahedrane 3D

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Dodecahedrane is a molecule of the molecular formula C20H20 which is shaped like a dodecahedron (a polyhedron having twelve faces).  It was first synthesized in 1982 by the research group of Leo A. Paquette at Ohio State University.

 
   
Spiro[4.4]nonane 3D

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Spiro[4.4]nonane is a spirocyclic compound, in which two fused rings share a single common carbon atom.

 

 

 

 

Alkyl Halides

Alkyl halides, or haloalkanes, are alkanes in which one or more hydrogen atoms are replaced by halogen atoms (fluorine, chlorine, bromine, or iodine).  The carbon-halogen bond is more polar than the carbon-hydrogen bonds, but most alkyl halides are not very soluble in water.  Alkyl fluorides and chlorides having only one halogen atoms have densities that are higher than those of alkanes, but are slightly less dense than water, while alkyl bromides and iodides are generally more dense than water.  Alkyl halides having more than one halogen atom are often more dense than water.

Alkyl halides are named as alkanes, with the halogens named as halo- substituents.  The halogens are named as fluoro-, bromo-, chloro-, and iodo- when attached to a carbon atom.  For example, the name "1-chloropropane" indicated a three-carbon chain with a chlorine atom on carbon number 1.  A number of simple alkyl halides are usually known by their common names; for instance, trichloromethane is almost always referred to as "chloroform." 

Chloromethane (Methyl chloride) 3D


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Chloromethane (methyl chloride) is a colorless gas at room temperature (boiling point -24C).  
   
Dichloromethane (Methylene chloride) 3D


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Dichloromethane (methylene chloride) is a colorless liquid at room temperature (boiling point 41C).  It is a very common solvent, but it is mildly toxic; it is more dense than water, having a density of 1.32 g/mL.  It is sometime used as a paint remover and degreaser.  It is used to decaffeinate coffee beans; since it has such a low boiling point, the residual solvent can be removed from the beans at fairly low temperatures.  

 

 
Trichloromethane (Chloroform) 3D


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Trichloromethane (chloroform) is a colorless liquid at room temperature (boiling point 60C).  Chloroform is a commonly used organic solvent, and like dichloromethane is more dense than water (d 1.48 g/mL).  Chloroform vapor is a anesthetic:  James Young Simpson was the first to use chloroform as an anesthetic during childbirth in 1846 (presumably, not on himself!), and it was widely used in surgery in the 19th and early 20th centuries.  However, since chloroform is carcinogenic, and toxic to the liver, it is not widely used for this purpose anymore.  (It's also useful for knocking out giant apes.)

Trihalomethanes are often referred to as haloforms; thus CHCl3 is chloroform, CHF3 is fluoroform, CHBr3 is bromoform, and CHI3 is iodoform.

 

 

 
Tetrachloromethane
(Carbon Tetrachloride)
3D


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Tetrachloromethane (better known as carbon tetrachloride) is a liquid at room temperature, with a density of 1.6 g/mL.  It used to be a common organic solvent, and was widely used for dry cleaning and spot removal.  However, it has been shown to be toxic and carcinogenic, so other solvents are used instead.  Carbon tetrachloride is also a contributor to ozone depletion (see Freon-12), and has been banned under the Montreal Protocols that set strict limits on the use of CFCs.  

 

 
1,1,1-Trichloroethane 3D


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1,1,1-Trichloroethane is a very commonly used organic solvent.  It was heavily used in dry cleaning, but it has been replaced by other solvents (such as tetrachloroethylene) under the Montreal Protocols (see Freon-12).  

 

 
Dichlorodifluoromethane (Freon-12) 3D


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Dichlorodifluoromethane (Freon-12) is an example of the chlorofluorocarbons (CFCs, or freons), which are organic compound containing fluorine and chlorine atoms.  These compounds were developed in the 1920s for use as refrigerants; prior to this, ammonia was used as a refrigerant, but the high toxicity of ammonia gas made this less than ideal.  The CFCs are relatively nontoxic, very unreactive, and boil at low temperatures, and were thus ideal for use in refrigeration equipment.  In addition, CFCs were widely used as aerosol propellants in spray cans, and as foaming agents in the manufacture of plastic foams (such as Styrofoam).

Unfortunately, the low reactivity of the CFCs leads to a major environmental problem:  they persist in the environment for a long time (up to a century), and eventually make their way into the upper atmosphere, where they damage the ozone layer.

Ozone, O3, is an allotropic form of molecular oxygen, O2, which is found in the stratosphere, at an altitude of 10 to 50 km above the surface of the Earth.  It is produced when photons (hn) of high-energy ultraviolet light (wavelengths of 242 nm or less) from the Sun splits oxygen molecules into oxygen atoms (O).  The oxygen atoms combine with oxygen molecules to make ozone:

This ozone that is produced from this reaction absorbs ultraviolet light with wavelengths of 320 nm or less, splitting into oxygen molecules and oxygen atoms,

which then re-combine to form ozone, which can absorb another photon of ultraviolet light.  The ozone in the ozone layer thus protects the surface of the Earth (and more importantly, the living organisms that make their home there) from much of the damaging high-energy ultraviolet light from the Sun.

When a molecule of Freon-12 drifts into the upper atmosphere, photons of high-energy light can strike it, causing it to release a chlorine atom:

The chlorine atom has an unpaired electron, and is a highly reactive free radical, which reacts with ozone in the stratosphere, converting it to molecular oxygen:

The chlorine atom is regenerated in this process, and behaves as a catalyst; one chlorine atom can destroy up to 100,000 ozone molecules.

The mechanism for ozone destruction was first published in 1974 by F. Sherwood Rowland and Mario J. Molina; they shared the Nobel Prize in Chemistry in 1995 with Paul Crutzen, who proposed a similar mechanism for the destruction of ozone by nitrogen oxides in 1970.

In 1987, an international agreement called the Montreal Protocol on Substances that Deplete the Ozone Layer was signed.  This treaty cut back on the production and use of CFCs; in 1990, partially in response to the alarming increase in the size of the "ozone hole" over the South Pole, the agreement was extended to become a ban on the use of CFCs starting in 2000.  It is believed that CFC levels in the stratosphere will continue to rise through the 2000s, and will not return to safe levels until the middle of the 2100s.

CFCs in refrigeration are being replaced by hydrochlorofluorocarbons (HCFCs), which are slightly more reactive than CFCs, and fall apart before reaching the stratosphere, and by hydrofluorocarbons (HFCs); in propellants they are being replaced mostly by carbon dioxide and low-boiling point hydrocarbons.

 
   
Chlorodifluoromethane (Freon-22) 3D


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Chlorodifluoromethane (Freon-22, HCFC-22) is an example of a hydrochlorofluorocarbon (HCFC), which were developed as replacements for chlorofluorocarbons (CFCs) (see Freon-12 above).  The HCFCs are not fully halogenated — i.e., not every hydrogen atom is replaced by a halogen atom.  Because of this, these molecules are less stable than the CFCs, and degrade to a larger extent before they reach the upper atmosphere.

 
   
1,1,1,2-Tetrafluoroethane (Freon-134a) 3D


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1,1,1,2-Tetrafluoroethane (Freon-134a, HFC-134a) is an example of a hydrofluorocarbon (HFC), an alternative to the chlorofluorocarbons (CFCs) which have been developed in response to the threat to the ozone layer that the CFCs pose (see Freon-12 above).  The HFCs contain only hydrogen, fluorine, and carbon, and are not damaging to the ozone layer.  Freon-134a is now widely used in the air conditioning systems of automobiles in place of Freon-12.

 
   
Bromochlorodifluoromethane (Halon 1211) 3D


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Bromochlorodifluoromethane (Halon 1211) is an example of a halon, a haloalkane that has bromine atoms in addition to chlorine and fluorine atoms.  Halons are very stable, and are useful in fire extinguishers, since they do not damage electronic equipment.  Their use has largely been phased out under the Montreal Protocols (see Freon-12 above), but they are still used in fire suppression systems aboard some aircraft, since no completely satisfactory and safe alternatives have been discovered.  
   
Dichlorodiphenyltrichloroethane (DDT) 3D


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Dichlorodiphenyltrichloroethane, or 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane, better knows as DDT, is an very powerful insecticide.  It was unique among the known insecticides at the time of its discovery in 1939, in that it was effective against insects, but not very toxic to mammals.  DDT was widely used to kill mosquitoes that spread malaria, and was also effective against the insects that spread sleeping sickness and typhus.  Unfortunately, DDT persists in the environment for a long time, and its accumulation in wildlife lead to decreases in the populations of several bird species.  In 1972, DDT was banned by the Environmental Protection Agency.  
               "A mosquito was heard to complain,
               "A chemist has poisoned my brain!"
                    The cause of his sorrow
                    Was para-Dichloro
               DiphenylTrichloroethane.
 
   
Lindane 3D


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Lindane, also known as gamma-hexachlorocyclohexane (HCH) and benzene hexachloride (BHC), is another common insecticide.  It is used in some shampoos to kill lice and other ectoparasites.  However, it is a suspected carcinogen, and is banned in California, and several countries.  
   
Chlordane 3D


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Chlordane was used as a pesticide on some crops, and was also used to kill termites.  Because of concerns about its toxicity, it was banned by the EPA in 1988.  

 

 

 

References

P. W. Atkins, Molecules, 2nd ed.  Cambridge: Cambridge University Press, 2003, p. 36-46.

Paula Yurkanis Bruice, Organic Chemistry, 4th ed.  Upper Saddle River:  Prentice Hall, 2004, p. 67-72, 88-99.

Marye Anne Fox and James K. Whitesell, Organic Chemistry, 3rd ed.  Sudbury:  Jones and Bartlett Publishers, p. 22-33.

Maitland Jones, Jr., Organic Chemistry.  New York:  W. W. Norton & Company, 1997, p. 108-110.

Richard J. Lewis, Sr., Hawley's Condensed Chemical Dictionary, 13th ed.  New York:  Van Nostrand Reinhold, 1997.

G. Marc Loudon, Organic Chemistry, 4th ed.  New York:  Oxford University Press, 2002, p. 268-269.

Robert Thornton Morrison and Robert Neilson Boyd, Organic Chemistry, 6th ed.  Englewood Cliffs:  Prentice Hall, 1992, p. 92-96.

D. W. A. Sharp, The Penguin Dictionary of Chemistry, 2nd ed.  London:  Penguin Books, 1990.

A. Truman Schwartz, Diane M. Bunce, Robert G. Silberman, Conrad L. Stanitski, Wilmer J. Stratton, and Arden P. Zipp, Chemistry in Context:  Applying Chemistry to Society.  Dubuque:  Wm. C. Brown Communicatiions, Inc., p. 27-57.

Graham Solomons and Craig Fryhle, Organic Chemistry, 7th ed.  New York:  John Wiley & Sons, Inc., 2000, p. 147-169, 230-231.

L. G. Wade, Jr., Organic Chemistry, 5th ed.  Upper Saddle River:  Prentice Hall, 2003, p. 80-92, 100-110, 215-217.

Martha Windholz (ed.), The Merck Index, 10th ed. Rahway: Merck & Co., Inc., 1983.