Organic Chemistry
-the study of carbon compounds
-there are millions of carbon compounds while there
are less than 50,000 compounds of all other elements
combined
-primary sources of carbon compounds include
petroleum (oil), plants and animals
Life is Organic Chemistry
Properties of Organic Compounds
• Organic compounds have covalent bonding and
thus have low melting points, generally less than
300˚C
• Organic compounds are generally nonpolar and
therefore insoluble in water, although low
molecular mass alcohols, organic acids and
amines are water soluble
• Organic compounds are generally
nonelectrolytes (do not produce conductive
solutions in water)
• Organic acids such as ethanoic acid(acetic acid)
are electrolytes
• Carbon has four valence
electrons (2s2, 2p2)
• Carbon needs to form four
covalent bonds in order to
complete the valence shell
• Carbon undergoes sp3
hybridization to form four
bonds
• The four bonds of carbon are
directed toward the corners of
a tetrahedron
• Carbon atoms can form single
double or triple bonds by
sharing one, two or three pairs
of electrons
• Carbon atoms can bond to
each other to form long chains,
branched or cyclic compounds
.
C:
.

.
.C.
.
Hydrocarbons
• Include only carbon and hydrogen atoms
• Include the homologous series
– Alkanes have only single bonds between
carbons
– Alkenes have a carbon-carbon double bond
– Alkynes have a carbon-carbon triple bond
Alkanes
• Are saturated molecules, meaning they have all
single bonds and cannot add any more atoms
• Are also called the paraffin series
• Names end in -ane
• Have the general formula CnH(2n+2)
• The simplest is CH4 which is the main
component of natural gas
• Are used as fuels in combustion reactions
• Can undergo substitution reactions with
halogens
Naming Organic Compounds
• count the number of carbons in the longest
C to C chain
• Select the appropriate prefix from Table P
• Look for double or triple bonds in the
carbon chain
– All single bonds, name ends in –ane
– Double bond present, name ends in –ene
– triple bond present, name ends in -yne
Prefixes for carbon chains
(Table P of reference tables)
•
•
•
•
•
•
•
•
•
•
•
# of C’s
1
2
3
4
5
6
7
8
9
10
Prefix
methethpropbutpenthexheptoctnondec-
When the carbon group is a
side chain off of the main chain,
it is named by adding -yl to the
prefix and describing it’s
location by carbon number
Start the numbering
at the end of the
chain that will give
the lowest number
for the address of the
side chain
3-ethyl octane
Isomers
• Isomers are compounds which
have the same molecular
formula, but different structural
formulas (arrangement of
atoms)
• In the alkanes, isomers are
possible beginning with four
carbons; The first three
carbons are linked end to end,
but the fourth carbon may be
added to the end of the chain
or added to the side at the
middle carbon
• The more carbon atoms, the
more possible isomeric
structures
Butane
C4H10
2-methyl propane C4H10
Alkenes
• Contain a carbon-carbon
double bond
• Have the general formula
CnH(2n)
• Are unsaturated and can
undergo addition reactions
• Names end in –ene
• Describe location of double
bond with carbon number
where it starts
• Number the chain to give the
multiple bond the lowest
possible number
H2C
CH2
ethene
CH2
CH3
propene
Alkenes
• Ethene and propene do
not need numbering for
the double bond because
the position is
unambiguous
• 1-butene and 2-butene
are isomers
• Isomers have the same
molecular formula, but
different structural
formulas
CH3
H2C
1-butene
H3C
2-butene
CH3
Alkynes
• Contain a triple
carbon-carbon bond
• Have general formula
CnH(2n-2)
• Names end in –yne
• Also called the
acetylene series after
the first member
• Are unsaturated and
can undergo addition
HC
Acetylene
CH
C2H2
IUPAC name is ethyne
Functional groups
Table R of the reference tables
• Functional groups contain atoms other
than C and H
• The most common functional groups
include halogens, and groups containing
oxygen and nitrogen atoms
• There are different suffixes to compound
names to describe most of the functional
groups
Functional groups
• Functional groups are atoms
other than carbon and
hydrogen in the carbon and
chain
• Halogen: fluoro-, chloro-,
bromo-, and iodo- are
described by their position
• For multiple substitution,
prefixes are used
• 2= di3 = tri- 4 = tetr(a)
5 = pent(a)
• For five and above the prefixes
are the same as the ones used
in table P for the carbon chain
numbers
• Each substituent gets a
number, so there must be
three numbers for tri-, 5 for
penta, etc
H
Cl
H
Cl
H
H
H
H
1,2-dichloropropane
H
H
Br
Br
H
Br
H
Br
1,1,3,3-tetrabromopropane
Alcohols
• Contain oxygen atoms
• Alcohols have an –OH
group on the carbon chain
• Alcohol names end in the
suffix –ol, just like the word
alcohol
• The simplest alcohols are
methanol and ethanol with
just one or two carbons,
respectively
methanol
CH3OH
ethanol
C2H5OH
Primary, Secondary and Tertiary
Alcohols
1-propanol
Primary alcohol
• 1-propanol is a primary alcohol
with the –OH group on an end
carbon attached to only one
other carbon
2-propanol
• 2-propanol is a secondary
alcohol with the –OH carbon
attached to two other carbons
Secondary alcohol
• 2-methyl-2-propanol is tertiary
alcohol because the alcohol
carbon is attached to three
other carbons
2-methyl-2-propanol
Tertiary alcohol
Ethers
• Ethers are molecules with an oxygen atom
between two alkyl groups: R-O-R
• An ether can be prepared by dehydration (aka
condensation) of two primary alcohols
• Ethers are named by using the prefixes for each
alkyl group followed by the word ether
• CH3OH + C2H5OHCH3OC2H5 + H20
• Methanol + ethanol  ethyl methyl ether
• The order of the alkyl groups is alphabetical
Ethers
• Unlike alcohols, ethers cannot hydrogen bond
between molecules so their boiling points are
lower than alcohols of similar mass, and their
vapor pressures are higher
• Diethyl ether was used as an anesthetic, but its
volatility and flammability made it very
hazardous to use, and less volatile/flammable
anesthetics were developed
Amines
• Amines contain a nitrogen heteroatom
• Low molecular mass amines have high vapor
pressures and offensive odors
• The putrid odors of decomposing fish or meat
are caused by organic amines
• Amines can be primary, secondary or tertiary,
depending on whether 1, 2 or 3 alkyl groups
have replaced the hydrogens on ammonia, NH3
• CH3NH2 is a primary amine
• (CH3)2NH is a secondary amine
• (CH3) 3N is a tertiary amine