Download Organic chemistry: hydrocarbons

Organic chemistry
hydrocarbon, any of a class of organic chemical compounds composed only
of the elements carbon (C) and hydrogen (H)
hydrocarbons as either aliphatic or aromatic
Aliphatic (from Greek aleiphar, “fat”) described hydrocarbons derived by
chemical degradation of fats or oils.
Aromatic hydrocarbons constituted a group of related substances obtained by
chemical degradation of certain pleasant-smelling plant extracts.
Aliphatic hydrocarbons are divided into three main groups according to the
types of bonds they contain: alkanes, alkenes, and alkynes
Aromatic hydrocarbons are those that are significantly more stable than their
Lewis structures would suggest; i.e., they possess “special stability.”
Alkanes have only single bonds,
Alkanes CnH2n + 2
Alkanes: methane, ethane, and propane
One compound, called n-butane, where the prefix n- represents normal, has
its four carbon atoms bonded in a continuous chain.
The other, called isobutane, has a branched chain
IUPAC names of unbranched alkanes
alkane formula
name
alkane formula
name
CH4
methane
CH3(CH2)6CH3
octane
CH3CH3
ethane
CH3(CH2)7CH3
nonane
CH3CH2CH3
propane
CH3(CH2)8CH3
decane
CH3CH2CH2CH3
butane
CH3(CH2)13CH3
pentadecane
CH3(CH2)3CH3
pentane
CH3(CH2)18CH3
icosane
CH3(CH2)4CH3
hexane
CH3(CH2)28CH3
triacontane
CH3(CH2)5CH3
heptane
CH3(CH2)98CH3
hectane
are characterized by the general molecular formula
Alkenes contain a carbon-carbon double bond,
Alkenes CnH2n
Alkynes contain a carbon-carbon triple bond.
Alkynes CnH2n – 2
 The most common other elements in organic compounds are
oxygen, nitrogen, sulfur, and the halogens.
The halogens resemble hydrogen because they need to form a single
covalent bond to achieve electronic stability. Consequently, a halogen atom
may replace any hydrogen atom in a hydrocarbon.
Halogens can replace any or all of the four hydrogens of methane. If the
halogen is fluorine, the series of replacement compounds is
CH 4 CH 3F CH 2F 2 CHF 3 CF 4
Such halogenated compounds are called organic halides or alkyl halides.
The substituted atoms may be fluorine, chlorine, bromine, iodine, or any
combination of these elements.
The previously mentioned ethylene molecule is planar; that is, all six atoms lie in a single plane
because the double bond is rigid
The configuration with the bromines adjacent is called cis (from the Latin derivative for “on this
side”), whereas the configuration with bromines opposite is called trans (which means “on the
other side”)