alkane

(noun)

Any of the saturated hydrocarbons—including methane, ethane, and compounds with long carbon chain known as paraffins, etc.— that have a chemical formula of the form CnH2n+2.

Related Terms

(noun)

Any of the saturated hydrocarbons (including methane, ethane, and compounds with long carbon chain known as paraffins, etc.) that have a chemical formula of the form CnH2n+2.

Related Terms

Examples of alkane in the following topics:

  • Reactions of Alkanes

    • However, there are a few classes of reactions that are commonly performed with alkanes.
    • The most important reaction that alkanes undergo is combustion.
    • Smaller, linear alkanes generally oxidize more readily than larger, more branched molecules.
    • For this reason, alkanes are frequently used as fuel sources.
    • The complex alkanes with high molecular weights that are found in crude oil are frequently broken into smaller, more useful alkanes by thermal cracking; alkenes and hydrogen gas are also produced by using this method.

  • Alkanes

    • The number of carbon atoms is used to define the size of the alkane (e.g., C2-alkane).
    • The simplest possible alkane is methane (CH4).
    • In linear alkanes, the carbon atoms are joined in a snake-like structure.
    • In branched alkanes, the carbon backbone splits off in one or more directions.
    • In cyclic alkanes, the carbon backbone is linked so as to form a loop.

  • Alkanes

    • The alkanes and cycloalkanes are also members of a larger class of compounds referred to as aliphatic.
    • A common "ane" suffix identifies these compounds as alkanes.
    • Longer chain alkanes are well known, and their names may be found in many reference and text books.
    • (i) The formulas and structures of these alkanes increase uniformly by a CH2 increment.
    • Beginning with butane (C4H10), and becoming more numerous with larger alkanes, we note the existence of alkane isomers.

  • Properties of Alkenes

    • Due to the presence of a double bond in their carbon skeletons, alkenes are more reactive than their related alkanes.
    • The sigma bond has similar properties to those found in alkanes, while the pi bond is more reactive.
    • Alkenes are more reactive than their related alkanes due to the relative instability of the double bond.

  • Naming Alkenes and Alkynes

    • Alkenes and alkynes are named similarly to alkanes, based on the longest chain that contains the double or triple bond.
    • The naming conventions for these compounds are similar to those for alkanes.
    • This longest chain is named by the alkane series convention: "eth-" for two carbons; "prop-" for three carbons; "but-" for four carbons; etc.

  • Cycloalkanes

    • The simplest examples of this class consist of a single, unsubstituted carbon ring, and these form a homologous series similar to the unbranched alkanes.
    • If a simple unbranched alkane is converted to a cycloalkane two hydrogen atoms, one from each end of the chain, must be lost.
    • Although a cycloalkane has two fewer hydrogens than the equivalent alkane, each carbon is bonded to four other atoms so such compounds are still considered to be saturated with hydrogen.
    • Substituted cycloalkanes are named in a fashion very similar to that used for naming branched alkanes.

  • Alcohol Reactions

    • Indeed, the dipolar nature of the O–H bond is such that alcohols are much stronger acids than alkanes (by roughly 1030 times), and nearly that much stronger than ethers (oxygen substituted alkanes that do not have an O–H group).

  • Addition Reactions

    • In halogenation, adding elementary bromine or chlorine to alkenes yields dibromo- and dichloro-alkanes, respectively.
    • In free radical additions of halogens to alkanes (or alkenes), a radical halogen can attack an alkane to produce another radical, in this case a radical version of the alkane.
    • The radical alkane can attack another compound, producing another radical that can continue on to attack another compound.

  • Cycloalkanes

    • Cycloalkanes, like alkanes, are subject to intermolecular forces called London dispersion forces.
    • Like alkanes, cycloalkanes are not particularly reactive, with the exception of the smallest, most strained cycloalkanes.
    • Cycloalkanes are named using the same conventions as linear alkanes, with the prefix cyclo- added to the front of the name.

  • Reactions of Alkenes and Alkynes

    • Alkenes and alkynes are more reactive than alkanes due to their pi bonds.
    • Alkenes and alkynes are generally more reactive than alkanes due to the electron density available in their pi bonds.
    • In the presence of a catalyst—typically platinum, palladium, nickel, or rhodium—hydrogen can be added across a triple or a double bond to take an alkyne to an alkene or an alkene to an alkane.
    • The halogenation of an alkene results in a dihalogenated alkane product, while the halogenation of an alkyne can produce a tetrahalogenated alkane.