Organic Chemistry
Organic chemistry: the study of carbon-based compounds, including their properties and reactions.
Saturated hydrocarbons:
Unsaturated hydrocarbons:
Saturated Hydrocarbons: the ALKANES: chains of carbon connected by single bonds: (end in –ane)
# C’s
Prefix
Alkane
Formula
Structure
1
-meth
Methane
CH4
2
-eth
Ethane
C2H6
3
-prop
Propane
C3H8
4
-but
Butane
C4H10
5
-pent
Pentane
C5H12
6
-hex
Hexane
C6H14
7 –hept
8 –oct
9 –non
10 –dec
“normal” hydrocarbons:
branched-chain hydrocarbons:
n-butane (formula:___________)
2-methylpropane (formula:___________)
n-pentane (formula:___________)
2-methylbutane (formula:___________)
Which ones are structural isomers of each other???
HINT: Structural isomers have the same chemical formula but different bonding structures --- different branching
Another branched alkane: 2,2-dimethylpentane
• cycloalkanes:
Unsaturated Hydrocarbons:
Alkenes: contain C-C double bonds (end in –ene)
Alkynes: contain C-C triple bonds (end in –yne)
Aromatic Hydrocarbons:
Benzene: the simplest aromatic hydrocarbon; has a symmetrical ring structure:
Derivatives of benzene:
1-ethyl-2-methylbenzene
1, 2-dimethyl-4-propylbenzene
Functional Groups
Functional groups: special groups of atoms attached to a hydrocarbon skeleton; the most common sites of
chemical reactivity
Organic halides: a hydrogen is replaced by a halogen (fluoro-, chloro-, bromo-, iodo-)
2-iodobutane
2,4-dibromo-1-hexene
1-bromo-2-chlorobenzene
Alcohols & phenols: contain the hydroxyl group (-OH)
alcohols: at least 1 H on a hydrocarbon is replace by OH
phenols: at least 1 H on an aromatic ring is replaced by OH
2-propanol
3-methyl-1-butanol
1,2-butanediol
Ethers: cmpds in which an O atom is bonded to 2 organic groups: -C-O-Cmethoxymethane
(dimethyl ether)
methoxybenzene
(methyl phenyl ether)
methoxypropane
(methyl propyl ether)
Carboxylic acids: (general formula is R-COOH)
named by dropping the terminal “e” from the parent hydrocarbon and adding “-oic acid”
butanoic acid
ethanoic acid
3-methylpentanoic acid
benzoic acid
Amines: derivatives of ammonia (NH3) in which 1 or more hydrogen atoms are replaced by organic groups
(alkyl or aryl groups)
ammonia
methylamine
trimethylamine
2-aminobutane
1-amino-3-propylcyclohexane
*aniline is the simplest aromatic amine:
aniline
N,N-dimethylaniline
3,5-dichrolroaniline
Summary of IUPAC rules for naming organic compounds
IUPAC: International Union of Pure and Applied Chemistry
International, non-governmental organization that is best known for its system of nomenclature, which is now
recognized as the world authority in this field.
Rule #1: Identify the longest chain of carbon atoms
a) The longest chain of carbon atoms gives the stem/root of the name as shown in the table below:
# of C-atoms in Stem in
Example
longest chain
IUPAC name
(C2H2n+2 for alkanes)
1
methCH4, methane
2
eth-
C2H6, ethane
3
prop-
C3H8, propane
4
but-
C4H10, butane
5
pent-
C5H12, pentane
6
hex-
C6H14, hexane
7
hept-
C7H16, heptane
8
oct-
C8H18, octane
9
non-
C9H20, nonane
b) If two chains have equal lengths, pick the one with more branch points.
Rule #2: Number the carbons in the main chain
Number chain to minimize the position/number of the following in order of priority:
a) thing you’re naming the compound after (double bond if alkene; -OH group if alcohol, etc)
note: for multiple double bonds -diene, -triene, -tetraene
b) first branch/substituent group
c) If both ends have the same first branching number, then number chain to minimize position of second
branch (and then third and so on).
d) if still in need of a tie breaker, minimize # of substituent group that comes first alphabetically
Note: in cyclic and aromatic (benzene derivatives) compounds, no number needed if only one substituent.
Rule #3: Identify the functional group and attach appropriate suffix
Note: the name for the stem/root is derived from the longest carbon chain, which may include the carbon of
the functional group.
Class of compound
alkane
Functional group
Suffix in IUPAC name
-ane
alkene
-ene
alkyne
-yne
alcohol
-anol
aldehyde
-anal
ketone
-anone
carboxylic acid
-anoic acid
amine
-anamine
Indicating position of the functional group: shown by a number inserted before the functional group ending.
The number refers to the carbon atom to which the functional group is attached when the chain is numbered
starting at the end that will give the smallest number to the group.
Rule #4: Identify the side chains or substituent groups
Assign number of carbon at point of attachment.
Side chain/ substituent group
-CH3
-C2H5
-C3H7
-F, -Cl, -Br, -I
-NH2
Prefix in IUPAC name
methylethyl
propylfluoro-, chloro-, bromo-, iodoamino-
Example
2-methylpropane
3-ethylpentane
4-propylheptane
tetrachloromethane
2-aminoethanioic acid
Rule #5: Assemble name as a single word  #, substituent, root, suffix
a) List substituents alphabetically (i.e. butyl- before methyl-)
b) If multiples of one substituent are present: “di-,” “tri-,” “tetra,” etc.
Note: “di-,” “tri-,” “tetra,” etc. aren’t part of alphabetical name (i.e. triethyl- before dimethyl-)
c) punctuation: commas between numbers; hyphens between numbers and letters; merged into one word
(exception: acid = word #2 for carboxylic acids)