Organic
Chemistry
DP Chemistry
What is Organic Chemistry?
 “Organic”
is a term that is used in a
variety of ways:



“from living things”
“chemical free”
“carbon-based”
Organic Chemistry is the study of carbon-based compounds
Carbon

Carbon is in Group IV of the
periodic table

Carbon has 4 valence
electrons

Carbon can form 4 covalent
bonds

Carbon can form single,
double and triple bonds with
a wide variety of elements
forming nearly ten million
known compounds
C
12
6
1s2 2s2 2p2
Tetravalent Carbon
Because carbon has four
valence electrons, it forms
four bonds with other
elements to make up a full
valence shell of 8. All
valence electrons are
involved in bonding.
Hydrogen
atoms
This bonding leads to
tetrahedral shapes when all
of the bonds involved are
single bonds.
Hydrocarbons are made up of
carbon bonded to
hydrogen, but many
elements can and do take
the place of hydrogen.
Carbon atom
Methane CH4
Chlorine
atoms
Carbon
atom
Common elements that bond
to carbon are N, O, S and
the halogens (e.g. Cl, F).
Carbon tetrachloride CCl4
Carbon Bonding
Structural
Formula
Molecular
Formula
H H
Single bond - ethane
H C C H
C2H6
H H
H
H
C C
H
Double bond - ethene
H
C2H4
Carbon Bonding
Triple bond – ethyne
(acetylene)
Cyclic– benzene
Structural
Formula
H C C H
Molecular
Formula
C2H2
C6H6
Fractional Distillation
Crude oil contains a mixture
of hydrocarbons ranging
from one carbon (C1) up
to more than C24.
Fractional distillation allows
for these components or
‘fractions’ to be
separated using a
fractionating column.
In this process, heat is
applied to the bottom of
the column and lighter
compounds with lower
boiling points rise to the
top, while heavier
compounds remain
towards the bottom of
the column.
Source:
http://www.bbc.co.uk/schools/gcsebitesize/chemistry/usefulproductsoil/oil_and_oilproductsrev5.shtml
Hydrocarbons
Alkanes - hydrocarbons that
contain only single bonds (all  bonds
and no  bonds - saturated). The table
to the right shows the alkane
homologous series (a family of
compounds that have the same
general formula differing by CH2).
Number of C
Alkane
1
Methane
2
Ethane
3
Propane
4
Butane
5
Pentane
6
Hexane
7
Heptane
8
Octane
Formula – CnH2n+2
Straight-chain alkanes – carbons
joined together to form a single chain
with no branching.
Structural formulae
Methane
Ethane
Propane
Butane
Hydrocarbons
Alkenes – hydrocarbons that
contain one double bond
between two carbon atoms.
Number of C
Alkene
1
NA
2
Ethene
3
Propene
4
Butene
5
Pentene
6
Hexene
7
Heptene
8
Octene
Formula – CnH2n
Isomers – compounds that have the
same molecular formula, but
different structure.
Alkenes have isomers because the
double bond can be in a different
location above C4. The location
of the double bond is indicated
by a numerical prefix counting
from the shortest end.
Condensed structural formulae
CH2
CH
CH2
1-butene
CH3
CH2
CH
CH2
1-pentene
CH2
CH3
CH2
CH
CH
CH2
CH3
2-pentene (NOT 3-pentene)
Hydrocarbons
Alkynes –
hydrocarbons that
contain one triple bond
between two carbon
atoms.
Formula – CnH2n-2
As with alkenes, a
numerical prefix indicates
the location of the triple
bond.
Number of C
Alkyne
1
NA
2
Ethyne
3
Propyne
4
Butyne
5
Pentyne
6
Hexyne
7
Heptyne
8
Octyne
Alkane b.p. trend
As alkanes get larger in size, the
intermolecular forces increase due to a
greater amount of dispersion forces.
The table below and graph to the right
show the trend in boiling point for
simple, straight-chain alkanes.
The longer the chain, the greater the
forces between molecules
Types of Formulae
4 Types:
1.
2.
3.
4.
Empirical –this shows the ratio
of elements in the compound
Molecular – shows the actual
number of atoms in a
compound, but no
information about how they
are arranged
Structural – shows the
arrangement of elements
and all of the bonds between
them. Most appropriate
Condensed Structural – omits
some or all of the bonds and
may show identical groups
bracketed together. These
are not acceptable when
asked for a structural formula.
e.g. CH3(CH2)4CH3
Molecular
Structural Formula
Condensed Structural
Structural Isomers
Structural isomers are
molecules that have the
same molecular formula,
but different structures.
Butane
Molecular formula: C4H10
Notice that changing the
structure, changes some
of the physical properties
Structural Isomers
Pentane
Notice again that changing the structure, changes some of the physical
properties. What pattern do you notice with these isomers? M.p./b.p. decreases with more branching
Naming Hydrocarbons
Examples of Simple Unbranched Alkanes
Name
Molecular
Formula
Structural
Formula
Isomers
Name
Molecular
Formula
Structural
Formula
Isomers
methane
CH4
CH4
1
hexane
C6H14
CH3(CH2)4CH3
5
ethane
C2H6
CH3CH3
1
heptane
C7H16
CH3(CH2)5CH3
9
propane
C3H8
CH3CH2CH3
1
octane
C8H18
CH3(CH2)6CH3
18
butane
C4H10
CH3CH2CH2CH3
2
nonane
C9H20
CH3(CH2)7CH3
35
pentane
C5H12
CH3(CH2)3CH3
3
decane
C10H22
CH3(CH2)8CH3
75
IUPAC
IUPAC – The International Union of Pure and Applied Chemistry is a group of Chemists
who devised a system of naming that allows for unique names to be applied to organic
compounds. There are many compounds that also have common names, but this
system allows us to speak a common language when naming these compounds. The
simple alkanes above are the simplest examples.
IUPAC - Naming hydrocarbons
Problem
Hexane C6H14 has 5
isomers. (See right)
How do we distinguish
between them?
Note: these are shorthand notations where each line
represents a bond between two carbon atoms
IUPAC “Quick” Rules for Alkane Nomenclature
1. Find and name the longest continuous carbon chain.
2. Identify and name groups attached to this chain. (These are called substituents.)
3. Number the chain consecutively, starting at the end nearest a substituent group.
4. Designate the location of each substituent group by an appropriate number and name.
5. Assemble the name, listing groups in alphabetical order using the full name (e.g. ethyl before
methyl). The prefixes di, tri, tetra etc., used to designate several groups of the same kind, are not
considered when alphabetizing.
Important notes:
• a hydrocarbon substituent becomes an alkyl group. (e.g. ethane becomes ethyl)
• Some substituents are “active sites” for reactions to occur (e.g. alcohols, ketones, alkenes) – these are
then also referred to as functional groups.
IUPAC names for the isomers?
n-hexane
2-methyl
pentane
3-methyl
pentane
2,2 –
dimethyl
butane
IUPAC “Quick” Rules for Alkane Nomenclature
2,3 –
dimethyl
butane
1. Find and name the longest continuous carbon chain.
2. Identify and name groups attached to this chain. (These are called substituents.)
3. Number the chain consecutively, starting at the end nearest a substituent group.
4. Designate the location of each substituent group by an appropriate number and name.
5. Assemble the name, listing groups in alphabetical order using the full name (e.g. ethyl before
methyl). The prefixes di, tri, tetra etc., used to designate several groups of the same kind, are not
considered when alphabetizing.
IUPAC – Naming Alkenes
IUPAC Rules for Alkene and Cycloalkene Nomenclature
1. The ene suffix (ending) indicates an alkene or cycloalkene.
2. The longest chain chosen for the root name must include both carbon atoms of the double bond.
3. The root chain must be numbered from the end nearest a double bond carbon atom. If the double
bond is in the center of the chain, the nearest substituent rule is used to determine the end where
numbering starts.
4. The smaller of the two numbers designating the carbon atoms of the double bond is used as the
double bond locator. If more than one double bond is present the compound is named as a diene, triene
or equivalent prefix indicating the number of double bonds, and each double bond is assigned a locator
number.
5. In cycloalkenes the double bond carbons are assigned ring locations #1 and #2. Which of the two is
#1 may be determined by the nearest substituent rule.
6. Substituent groups containing double bonds are:
H2C=CH– Vinyl group
H2C=CH–CH2– Allyl group
But-1-ene
But-2-ene
Functional Groups
Functional groups are specific groups of atoms or bonds within a compound
that are responsible for characteristic chemical properties of those substances.
Amines, Amides,
Esters and Nitriles
are HL only
Alcohols
R-OH
Alcohols contain the hydroxyl group
(OH) in place of a H atom in a
hydrocarbon.
Formula – CnH2n+1OH
Formula
Name
CH3OH
Methanol
CH3(CH2)OH
Ethanol
CH3(CH2)2OH
Propanol
CH3(CH2)3OH
Butanol
CH3(CH2)4OH
Pentanol
CH3(CH2)5OH
Hexanol
Compound suffix – “anol”
A number is used to indicate the
location of the hydroxyl on a
carbon chain in the same manner
previously described.
Alcohols follow the same trend in
b.p. as the hydrocarbons, but are
all higher due to H-bonding.
Propan-1-ol
Aldehydes
R-CHO
Aldehydes contain the carbonyl
group (C=O) which is bonded to
the last (terminal)carbon in a chain.
Formula – CnH2nO
Formula
Name
HCHO
Methanal
CH3CHO
Ethanal
CH3CH2CHO
Propanal
CH3(CH2)2CHO
CH3(CH2)3CHO
CH3(CH2)4CHO
Butanal
Pentanal
Hexanal
Compound suffix – “anal”
No numbers are necessary for the
naming of aldehydes as the group is
on the terminal carbon.
Because of the carbonyl, there are
permanent dipoles leading to
stronger IM forces than alkanes, but
weaker than alcohols.
Propanal
Ketones
R-COR’
Ketones contain the carbonyl group
(C=O) which is bonded to a carbon that
is not on the terminal end. This placement
is how they differ from aldehydes.
Formula – CnH2nO
Formula
Name
CH3COCH3
Propanone
CH3(CH2)COCH3
Butanone
CH3(CH2)2COCH3 Pentanone
CH3(CH2)3COCH3 Hexanone
Compound suffix – “anone”
A number is used to indicate the location
of the carbonyl on a carbon chain.
Because of the carbonyl, there are
permanent dipoles leading to stronger IM
forces than alkanes, but weaker than
alcohols.
Butan-2-one
Carboxylic Acids
R-COOH
Carboxylic acids contain the carbonyl
group (C=O) and the hydroxyl (OH)
group.
Formula – CnH2nO2
Compound suffix – “anoic acid”
These compounds are polar towards the
O atoms, away from the H atom, making
the H atom available in acid/base rxns.
Because of the carbonyl and the
hydroxyl, Hydrogen bonding occurs
between these molecules.
Formula
Name
HCOOH
Methanoic
acid
CH3COOH
Ethanoic acid
CH3CH2COOH
Propanoic acid
CH3(CH2)2COOH Butanoic acid
CH3(CH2)3COOH Pentanoic acid
CH3(CH2)4COOH Hexanoic acid
Ethanoic
acid
Halides
Formula
Name
CH3Cl
chloromethane
CH3CH2Br
Bromoethane
CH3(CH2)2I
Iodopropane
CH3(CH2)3Cl
Chloropropane
Formula – CnH2n+1X
CH3(CH2)4Br
Bromobutane
Compound prefixes – “chloro”, “bromo”,
“iodo”
CH3(CH2)5I
Iodohexane
R-X
Halogenoalkanes contain the halide
functional group, which is a halogen
(X)atom in place of a hydrogen.
These compounds are named with the
corresponding halogen atom at the
beginning with the remainder of the
compound named as per the rules for
hydrocarbons.
Again, a number is used to indicate the
position of the halogen on the carbon
chain. More than one halogen may be
present
2-chloropropane
Primary, Secondary, Tertiary
alcohols and halides
Primary (10): When
a functional group
is attached to a
carbon that is
bonded to only
one other carbon
atom.
Secondary (20):
When a functional
group is attached to
a carbon that is
bonded to two other
carbon atoms.
Tertiary (30): When a
functional group is
attached to a
carbon that is
bonded to 3 other
carbon atoms.
For you to do:
Name the three
alkyl halides
above
Other functional groups
• R-NH2
• R-C6H5
• R-COR’
What functional groups can
you see?
Benzene
ring
Carboxylic
acid
IBUPROFEN
What functional groups can
you see?
Carboxylic acid
Ester
What functional groups can
you see?
Carboxylic acid
Amine
An amino acid
Amines (AHL)
R-NH2
Amines contain the amino group
(NH2) somewhere in the
hydrocarbon chain.
Formula – RNH2
Formula
Name
CH3NH2
Methylamine or
Aminomethane
CH3(CH2)NH2
Ethylamine or
Aminoethane
CH3(CH2)2NH2
Propylamine or
Aminopropane
Compound suffix – “ylamine”
OR
Compound prefix – “amino”
A number is used to indicate the
location of the amino on a carbon
chain in the same manner
previously described.
1-butylamine
Amides (AHL)
R-CONH2
Amides contain the amino group
(NH2) and a carbonyl group (C=O).
Formula
Name
HCONH2
Methanamide
CH3CONH2
Ethanamide
CH3CH2CONH2
Propanamide
Formula – RCONH2
Compound suffix – “anamide”
Amides are the same structure as
carboxylic acids with the amine
group replacing the hydroxyl.
butanamide
Esters (AHL)
R-COOR’
Esters contain the carbonyl group
(C=O) with an additional O
attached to the carbon.
Formula – RCOOR’
Compound suffix – “yl oate”
Esters are named in two parts from
the carboxylic acid and alcohol
that they are made from.
The first part of the name comes
from the alcohol and the second
from the acid.
Nitriles (AHL)
R-CN
Nitriles (aka cyanides) contain the
cyano group which is a carbon
triple bonded to a nitrogen.
Formula
Name
CH3CN
Methanenitrile
CH3(CH2) CN
Ethanenitrile
CH3(CH2)2CN
Propanenitrile
Formula – RCN
Compound suffix – “nitrile”
Nitriles are named by their
hydrocarbon chain with nitrile
added at the end.
pentanenitrile