Alkanes, Alkenes, and Alkynes (Hydrocarbons)

In organic chemistry, a hydrocarbon is an organic compound consisting completely of hydrogen and carbon. The carbon atoms combine together to create the framework of the compound, and the hydrogen atoms attach to them in many possible configurations. Hydrocarbons are the primary elements of petroleum and natural gas. They serve as fuels and lubricants as well as raw materials for the manufacturing of plastics, fibres, rubbers, solvents, explosives, and industrial chemicals.

Types of Hydrocarbons

Saturated hydrocarbons are the simplest of the different kinds of hydrocarbons. They are formed completely of single bonds and are saturated with hydrogen. The most basic form of saturated hydrocarbons is C_nH_2n+2,. Those with only one ring are the cycloalkanes. Saturated hydrocarbons are the basis of petroleum fuels and are found either as linear or branched species. Substitution reaction is their fundamental property (like chlorination reaction to form chloroform) (like chlorination reaction to form chloroform).
Unsaturated hydrocarbons feature one or more double or triple bonds between carbon atoms. Those with double bond are termed alkenes. Those with one double bond have the formula CnH2n (assuming non-cyclic structures). Those with triple bonds are termed alkyne. While the ones with one triple bond have the  formula
C_nH_{2n − 2}..
Aromatic hydrocarbons, commonly known as arenes, are hydrocarbons that have at least one aromatic ring. 10 percent of total nonmethane organic carbon emission are aromatic hydrocarbons from the exhaust of petrol or diesel vehicles.

Alkanes

Alkanes, or saturated hydrocarbons, possess only single covalent bonds between carbon atoms. Each of the carbon atoms in an alkane has sp3 hybrid orbitals and is bonded to four other atoms, which are either carbon or hydrogen. Carbon chains are frequently represented as straight lines in Lewis structures, however one has to remember that Lewis structures are not designed to indicate the geometry of molecules. The alkanes have two primary commercial sources: petroleum (crude oil) and natural gas.

Properties of Alkanes

Boiling point-Alkanes experience intermolecular van der Waals forces. Stronger intermolecular van der Waals forces give rise to greater boiling points of alkanes.
Melting points– The melting points of the alkanes follow a similar pattern as boiling points. That is, (all other factors being equal) the bigger the molecule the higher the melting point. The melting points of branched-chain alkanes can be either higher or lower than those of the equivalent straight-chain alkanes, again depending on the capability of the alkane in question to pack well in the solid phase.

Conductivity and solubility

Alkanes do not conduct electricity in any way, nor are they considerably polarized by an electric field. Due to this reason, they do not form hydrogen bonds and are insoluble in polar solvents such as water.

Application of Alkanes

The uses of alkanes depend on the quantity of carbon atoms. The first four alkanes are used largely for heating and culinary purposes, and in certain countries for power production. Methane and ethane are the major components of natural gas; they are generally stored as gases under pressure. It is, nevertheless, easier to transport them as liquids: This involves both compression and cooling of the gas.
Other Alkanes have other diverse applications.

Alkenes

Organic compounds that include one or more double or triple bonds between carbon atoms are regarded as unsaturated.   These are complex organic compounds with long chains of carbon atoms, which have at least one double bond between carbon atoms. Unsaturated hydrocarbon compounds that include one or more double bonds are termed alkenes. Carbon atoms joined by a double bond are held together by two bonds, one σ bond and one π bond. Double and triple bonds give rise to a distinctive geometry around the carbon atom that participates in them, leading to important variations in molecule form and characteristics. The varied geometries are responsible for the distinct characteristics of unsaturated vs saturated fats.
Ethene, C₂H₄, is the simplest alkene. Each carbon atom in ethene, usually termed ethylene, has a trigonal planar structure. The second member of the series is propene (propylene); the butene isomers follow in the series. Four carbon atoms in the chain of butene allows for the formation of isomers depending on the location of the double bond, as well as a new form of isomerism.

Alkynes

In organic chemistry, an alkyne is an unsaturated hydrocarbon having at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the standard chemical formula C_nH_{2n − 2}. Alkynes are commonly known as acetylenes, while the term acetylene also applies exclusively to C₂H₂, recognized formally as ethyne using IUPAC nomenclature. Like other hydrocarbons, alkynes are usually hydrophobic.

Uses of Alkynes

1. The most familiar form of alkynes Ethyne is commonly used for manufacturing organic chemicals like ethanol, ethanoic acid, acrylic acid, etc. Ethyne is also utilized for preparing several organic solvents.
2. As a fuel in oxyacetylene flame. The most significant alkyne is C₂H₂, usually termed acetylene. The burning of acetylene generates a highly hot and brilliant flame.
3. For the production of acetaldehyde, acetic acid, and ethyl alcohol. Some of these alkynes are utilized to produce organic compounds such as ethanoic acid, acrylic acid, and ethanol.
4. As fuel. The overriding alkyne in acetylene is utilized as a fuel where several kilos are manufactured per year by fractional oxidation of natural gases. Acetylene was originally used to light moveable lamps, which were known as acetylene gas lamps, mounted in homes, bicycles and on cars.

Conclusion

Any hydrocarbon possessing either a double or triple bond is an unsaturated hydrocarbon. Alkenes have a carbon-to-carbon double bond. The typical formula for alkenes with one double bond is C_nH_2n. Alkenes can be straight chain, branched chain, or cyclic. Simple alkenes commonly have common names, although all alkenes can be named using the method of the International Union of Pure and Applied Chemistry and have the ending -ene.
Alkynes have a carbon-to-carbon triple bond. The general formula for alkynes is C_nH_{2n − 2}. The characteristics of alkynes are nearly identical to those of alkenes. They are named somewhat like alkenes but with the ending –yne. Alkynes have a carbon-to-carbon triple bond. The general formula for alkynes is C_nH_{2n − 2}.