SCH4U
Unit 1
Organic Chemistry
Organic Chemistry
• Definition: the chemistry of carbon compounds
• Must contain carbon, may be in covalent
combination with hydrogen, oxygen, nitrogen,
sulfur or phosphorus
• Occurs in all living things, no life exists without
carbon.
• Exception – not all carbon containing
compounds are considered organic. (carbonates
and oxides)
History of Organic Chemistry
• At the beginning of modern chemistry, all
organic compounds were obtained from
naturally occurring organic matter.
– Soaps were obtained from fats,
– Dyes and drugs from plants
– Henna from lawsonia shrub
Evolution of Organic Chemistry
• 1828, synthesis the first organic compound: urea
from ammonia and cyanic acid began an
enormous ongoing religious debate
• a synthesized compound has no difference in
the chemical or physical properties of a naturally
occurring compound.
• today organic is acquiring meaning that suggest
mysterious vital forces. i.e.. “organic food”
“organic gardening” “organic vitamins”
The Amazing Carbon Atom
• Most unusual property of carbon is its ability to combine
with itself; this ability makes the number of potential
organic compound nearly infinite
• 10 million organic compounds are already known, each
with unique structures, names, chemical and physical
properties.
• 95% of all known compounds are organic compounds
• Carbon always contains four covalent bonds, usually to
hydrogen, sulfur, nitrogen, oxygen, halogens as well as
other carbon atoms
Organic Organization
• Chemists have organized organic compounds
into families
• Each family consists of compounds of similar
molecular structure and properties
• The largest family are the Hydrocarbons
• Hydrocarbon Family is divided into:
The Alkanes
The Alkenes
The Alkynes
The Aromatics
Naming Hydrocarbons
# of Carbons
Prefix
C-C
C=C
C C
1
2
3
4
5
6
7
8
9
10
Meth
Eth
Prop
But
Pent
Hex
Hept
Oct
Non
Dec
ane
ane
ane
ane
ane
ane
ane
ane
ane
ane
ene
ene
ene
ene
ene
ene
ene
ene
ene
yne
yne
yne
yne
yne
yne
yne
yne
yne
The Alkane Family
• At room temperature, alkanes from 1 to 4
carbon atoms are gases. 5- 16 carbon atoms
are liquids, 17 or more are solids.
• Non-polar molecules, colourless, odourless
• Relatively inactive
• Most important property, burn producing a lot
of heat; mainly used as fuels.
• All hydrocarbons can undergo complete
combustion into carbon dioxide and water
Structure of Alkanes
• Each carbon contains four covalent bonds to
four different atoms.
• Carbons are joined by single covalent bonds
H
H
H
H
C
H
C
H
H
C
H
C
H
H
H
C
H
H
C
H
Methane
• Simplest alkane
H
• Main component of
natural gas
• Contributing green
house gas
• Used as fuel
C
H
H
H
Ethane
Propane
• Second most simple
alkane
• Minor ingredient of
natural gas
H
H C
H
H
C
H
• Also known as bottled
gas
• Found in natural gas,
but separately for
commercial purposes
H
H
H C
H
H
C
H
H
C
H
H
Butane
• Gas used in butane lighters
• Four carbon chain allows for
different constitutional isomers.
- Compounds which share the
same molecular formula but
differ in their structural formula
Do you remember the difference
between sec-butyl, isobutyl,
tert-butyl or n-butyl groups?
Question #1: Can you draw:
H
H
C
H C
H
H
H
H
H
C
H
H
H
C H
C
H
H
H
H
C
C
H
4-tert-butyl-4-isobutyl-5-n-butyl-5-sec-butylnonane?
H
C H
H
Higher Alkanes
• Pentane, Hexane,
Heptane, Octane,
Nonane are all used to
make gasoline
• Decane used to make
kerosene
• All are derived from
crude oil through a
process called
“Cracking” – breaking
longer chain
hydrocarbons into
smaller chains
Alkenes
• Contain a double bond between
two or more carbon atoms
• Considered “unsaturated”
• Non-polar, insoluble in water
• Chemically reactive
• Lighter alkenes are gases at
room temperature
• Heavy alkenes are liquids or
solids with low melting points
Name
Formula
B.P.
Methane
CH4
-162
Ethane
C2 H6
-89
Propane
C3 H8
-42
Butane
C4H10
-1
Pentane
C5H12
36
Hexane
C6H12
69
Heptane
C7H14
98
Octane
C8H16
126
Properties of Alkenes continued…
• Occur widely in nature, fruits and
vegetables give off ethene which
triggers further ripening
• Red colour of tomatoes is a result of
lycopene, a hydrocarbon with many
double bonds
Ethene
H
• Simplest member if the
alkene family, also called
ethylene
• Most important
commercial organic
chemical
C
H
• U.S. production over 20
billion kg, more than have
is used in the production
of polyethylene, one of
the most familiar plastics.
H
C
H
Higher Level Alkenes
• Alkenes containing four carbons provide the opportunity
for isomerization, a change in the location of the double
bond.
• Different double bond positions result in different
chemical properties.
• Question: Why do we want to buy foods that have 0
trans fats?
• Can you name these compounds?
H
C C
H
H
H
C
H
H
C H
H
H
H C C
H
H
H
C
H
C H
H
Alkynes
• Each alkyne molecule
contains at least one triple
bond between carbon atoms
• Unsaturated, reactive
• Non-polar, do not dissolve in
water
• Burn in the presence of
oxygen
• Gases liquids, or low melting
solids at room temperature
Ethyne
• Commercially
known as
acetylene
• Used as a fuel in
welding torches
• Used in the past as
a surgical
anesthetic
H C C H
Higher Level Alkynes
• alkynes containing four carbons provide
the opportunity for isomerization, a
change in the location of the triple bond.
• Different triple bond positions result in
different chemical properties
H
H
C C
C
H
H
C H
H
H
H
H C C
H
C
C H
H
Hydrocarbon Comparison
H
H
H C
H
H
H
C
H
C
C H
H
H
H
C
H
propane
H
C
propene
H
H
H C C
C H
H
propyne
Boiling Point
-42.1 °C
-47.8 °C
-23.2°C
Melting
Point
-187.7 °C
-185.3 °C
-102.7°C
Aromatic Hydrocarbons
• All float on water, used
mainly as solvents and fuels
• Vapours can act as
narcotics when inhaled
• Benzene can cause
leukemia with prolonged
exposure
• Naphthalene is used an an
insecticide (mothballs)
Reactivity of the C-C Bond
• Relative reactivity
– Unsaturated C-C bonds = increased reactivity
– Alkynes > Alkenes > Aromatics > Alkanes
Reactions of Hydrocarbons
• Possibly the most important reaction of
hydrocarbons of low molar mass is that
they burn in the presence of oxygen Combustion
– liberates large amounts of energy as light and
heat, making them invaluable as fuels:
• Combustion of Octane
2 C8H18 + 25 O2  18 H2O + 16 CO2
Reactions of Alkanes
• ALKANES: Reactions with halogens to
form “alkyl halides” or “halocarbons”–
halogenated alkane
– Substitution reaction
• Rule: One H atom from the alkane is
substituted for one halogen atom. The H
atom that is removed combines with the
other atom of the halogen.
Reactions of Alkanes
• Methane gas is heated with an excess of chlorine
gas.
CH4 + Cl2 → CH3Cl + HCl
• Propane reacts with excess bromine
C3H8 + Br2 → C3H7Br + HBr
• Octane reacts with fluorine gas
C8H18 + F2 → C8H17F + HF
• Reactions with F2 are vigorous, but Cl2 and Br2
require heat or UV light to dissociate the halogen
molecule
Reactions of Alkenes and Alkynes
• ALKENES/ALKYNES: Additions across the
double or triple bond
– Addition Reaction – an atom is added to the
molecule without the loss of hydrogen
– Undergo addition reactions with
•
•
•
•
Halogens
Hydrogen
Hydrogen halides
Water
• Rule: The reactants are generally just
added together
Reactions of Alkenes and Alkynes
• Halogenation – addition of an halogen (X2)
H
H
H
+
H
Br
Br
→
H
Br
20oC
Br
H
H
H
• Hydrogenation – addition of hydrogen (H2)
H
H
+
catalyst
2H
H
→
Heat, pressure
H
H
H
H
H
H
Reactions of Alkenes and Alkynes
• Hydrohalogenation – addition of a
hydrogen halide
H
H
H
H
+
H-Br
→
Br
H
H
H
20oC
H
H
H
H
H
H
OH
H
• Hydration – addition of water
H
H
H
H
+
H2O
H2SO4
→
H
H
H
H
H
H
H
H
Markovnikov’s Rule
• This is an empirical rule based on Markovnikov's
experimental observations on the addition of hydrogen
halides to alkenes.
• "when an unsymmetrical alkene reacts with a hydrogen
halide to give an alkyl halide, the hydrogen adds to the
carbon of the alkene that has the greater number of
hydrogen substituents, and the halogen to the carbon of the
alkene with the fewer number of hydrogen substituents”
• “the rich get richer”
Markovnikov’s Rule
• “the rich get richer”
• Mechanistic Info
Reactions of Aromatic Hydrocarbons
• Aromatics are less reactive than alkenes due to
resonance stability
• do not normally undergo addition reactions (only under extreme
conditions)
• Substitution Reactions – H’s on benzene ring
more easily replaced than H’s on alkanes
• Benzene + Br2 → bromobenzene + HBr
• Bromobenzene + Br2 → 1,3-dibromobenzene
• Benzene + nitric acid (H2SO4)→ nitrobenzene + H2O
• Benzene + ethyl chloride (AlCl3)→ ethyl benzene + HCl
Functional Groups
• Functional groups are specific groups of atoms
that exhibit characteristic properties when
bonded to hydrocarbons
• The functional groups are:
Alcohols
Ethers
Aldehydes
Amines
Carboxylic Acids
Ketones
Esters
Alcohols
• Alcohols have an OH group
added on in place of a
hydrogen
• Tend to be polar, dissolving in
water
• Highly flammable, used as
fuels, antiseptics, beverages
and others
H
Methanol
C
• important solvent
H
• possible replacement for gasoline
• Toxic – methanol is oxidized in the body
to formaldehyde
• 30 mL can cause blindness or death
• Smaller amounts result in nausea,
convulsions, respiratory failure
H
O
H
Ethanol
• Alcohol found in wine, liquor or beer
• Industrial ethanol made from ethene is cheaper
because it generally lacks the same taxes on the
“recreational” alcohol
• Although identical, industrial contains a noxious
substance to prevent people from drinking it.
• A solution of 70% ethanol by volume acts as an
antiseptic by coagulating bacterial proteins
H
H
C
H
H
C
H
OH
Isopropanol
• Commonly called rubbing alcohol
• Used to give sponge baths to reduce high fevers.
• Alcohol quickly evaporates removing heat from the skin
surface, lowering one’s temperature
H
H
C
H
OH
C
H
H
C
H
H
Propanetriol
• Commonly known as glycerol, or glycerin
• Very thick, sweet tasting compound
• Nontoxic, excellent carrier of medicine
• Used by cosmetic industry in hand and skin creams
because it acts as a good lubricant
HO
OH
C
H C
H
H
OH
C H
H
Ethers
• Extremely flammable
H
• Anesthetic properties
• Diethyl ether most common
ether to medical personal
H C
H
H
H
C O C
H
H
• Used in long surgical procedures.
• Extremely safe anesthetic because there is a large
difference in dosage between that needed to
anesthetize and that needed to kill
• No longer used because of high flammability
H
C H
H
Aldehydes
O
• Formaldehyde is the
simplest and best known
C
H
• When dissolved in water,
it is used as a germicide,
disinfectant, and
preservative
• Used to preserve tissue
H
How do you make an
aldehyde starting from an
alcohol?
Do you need a primary,
secondary or tertiary
alcohol?
Ketones
H
H C
• Propanone, also known as
acetone is the simplest ketone
H
O
C
H
C H
H
• Found in paint and nail polish
removers
• Found in small amounts in the
blood. Large amounts indicate
diabetes mellitus
• This individual will have acetone
smelling breath.
Do you remember
how to make a
ketone?
Carboxylic Acids
• Simplest carboxylic acid
is methanoic or formic
acid
• Bee, wasp and hornet
venom contains some
formic acid
• Often have powerful,
unpleasant odours
– Rancid butter
– Body odour
Butanoic acid
O
C
H
O
H
Esters
• Quite fragrant even
when dilute
• Many have fruity
odours and tastes
• Used in flavourings for
candies, as well as
ingredients in perfume
H
H C
H
H
C O
H
O
C
H
Amines
• Generally have a strong smell
• Produced when living organisms decay
• Cadavarine shown below is the compound
responsible for the smell of rotting fish
H
H
N
H
H
C C
H
H
H
H
H
C N
C
H
H
H
Applications of Hydrocarbons
• Carbon is able to form strong single, double and triple
bonds with itself.
• This allows carbon to form long chains of atoms with
a variety of geometrical shapes.
• Long chains called polymers are stable under
standard conditions of temperature and pressure.
POLYMERS – Plastics,
Nylons, and Food
An Introduction to Polymers
Polymers
Greek for ‘many’ ‘parts’
• Polymers are long molecules made up of many
similar or identical building blocks linked by
covalent bonds
• The word polymer is Greek for ‘many’ ‘parts’
• Polymers include:
– Synthetic:
• Plastics
• Polyester, Nylon, Kevlar
• Teflon
– Natural:
•
•
•
•
Rubber
Cotton (cellulose), Silk (proteins), Wool (cellulose)
Proteins
DNA
Polymers
• Macro-molecule consisting of
repeating monomer subunits
• include every type of plastic, all
proteins, DNA, cotton, silk, wool,
etc.
• first synthetic plastic, celluloid, was
made from pyroxylin as part of a
contest to produce an ivory
substitute for billiard balls
Synthetic Polymers
• Polymers are molecules made up of repeating
molecules called ‘monomers’.
• The properties of the monomer affects the
properties of the polymer
• One of the simplest polymers is polyethylene
• This polymer is synthesized through an addition
reaction of ethene molecules
+
→
Polyethylene
• most important polymer
• used in plastic bags, bottles, straws etc.
• made from joining ethene monomers into a
repeating saturated polyethylene molecule
• forms a thermoplastic material, which can be
softened by heat and remolded into various
forms
Two Forms of Polyethylene
• High-Density
Polyethylene
• Low Density
Polyethylene
– forms a highly ordered
arrangement, resulting in a
rigid material
– used to make toys, bottle
caps, plumbing pipes
– molecules are more
randomly distributed ,
resulting in a semi-rigid,
translucent plastic,
resistant to many
chemicals, and has a high
degree of flexibility
– used in electrical wire
insulation, plastic bags,
bottles
Polyethylene
• There are two types of PE:
– LDPE
– HDPE
• LDPE:
– The chains have a high degree of branching. The chains
therefore do not pack well. Therefore it has less intermolecular
forces. The branching allows the plastic to serve in diverse
types of applications
Ex. Grocery bags, wire insulation, containers
• HDPE:
– The chains have a low degree of branching. The chains can
therefore pack closely, adding to the intermolecular forces.
Ex. Containers for milk, water and juice, garbage containers, toys
Polystyrene
• colour and filler is added to make inexpensive
toys, household items, throw away drinking cups
• gas can be blown into polystyrene liquid
resulting in a foam which hardens into Styrofoam
• used as insulation, packaging material, coffee
cups
Polyvinyl Chloride
• Tough synthetic material
• Vast properties including:
– Clear rigid material
– Long-lasting floor covering
– Lightweight, rustproof
plumbing
Teflon
• Non-stick coating
• All hydrogen atoms in ethylene are
replaced by fluorine
• Polymerization produces
polytetrafluoroethylene (PTFE), or
Teflon
• C-F bonds are exceptionally strong,
heat and chemical resistant,
unreactive and non-flammable
Can you draw tetrafluoroethylene? How do you
think two of these molecules link together?
Rubber
• Natural rubber is obtained from various tropical
plants
• monomer from which rubber is composed is
called isoprene
• natural rubber not very useful; sticky in warm
weather, hard and brittle in cold weather
Vulcanization
• Discovered by Charles Goodyear, rubber took on
more favorable properties over a wider range of
temperatures when heated in the presence of
sulfur
• vulcanization allows chains of rubber to cross-link
• the number of crosslinks between the strands of
rubber determine how stretchy, or hard the rubber
will be
Other Synthetic Polymers
• Synthetic polymers can be made with cross linking, as in
the case of Kevlar.
– This enhances strength
• Nylon is a polymer made to mimic the properties of silk
protein
– It is synthesized through the reaction of hexanedioic acid (adipic
acid) and 1,6-hexanediamine (hexamethylene diamine)
Natural Polymers
• These include
– Proteins
• Polyamides made up of 20 different amino acids
– Starch and cellulose
• Polysaccharides composed of sugar monomers
– Nucleic acids
• Backbone of alternating sugar and phosphate
group. Monomer of nucleotides
Proteins
• Amino acids contain two functional groups:
– An amine group and a carboxylic acid group
• There are 20 different natural occurring
amino acids. -Can you name them?
– There are 9 essential amino acids that must
be ingested as they are not synthesized by
the body
Amino acid
20 Amino Acids
Proteins are formed when an amine of one amino
acid reacts with the carboxylic acid of another
amino acid
– This bond formed is called a ‘peptide bond’
– The polymer is called a polypeptide
Proteins and Chirality
• A chiral carbon is a carbon with 4 different
attached groups.
• It exists as two different isomers. These isomers
are mirror images of each other.
• This chirality plays a key role in biological
systems.
• Often these isomers
cause different effects
in the body.
Thalidomide
• This was a drug used in late 1957- the early
60’s to treat pregnant women for morning
sickness.
• One isomer reacts as an effective sedative.
• The other isomer is tetragenic
– Caused fetuses to develop abnormally.
– Resulting in deformation of limbs.
• The medication administered was a
combination of both isomers.
Levels of Protein Structure
• There are 4 levels of protein structure: 1º, 2º, 3º, 4º
– Primary: the sequence of amino acids in the
polypeptide chain
– Secondary: the arrangements of the polypeptide
chain caused by van der Waals forces
• α-helix, β-sheets
– Tertiary: the unique 3D arrangement of a unit
• Stabilized by other interactions: covalent bonds,
hydrogen bonds
– Quaternary: protein subunits join through
intermolecular forces forming one functional
protein
Diagram of Levels of
Protein Structure
Starch and Cellulose
• These are carbohydrate polymers composed of
sugar monomers:
• They are called polysaccharides
• Plants are an excellent source of carbohydrates
• All carbohydrates have the empirical formula
Cx(H2O)y
• Glucose, the sugar made from photosynthesis
has the formula C6(H2O)6 or C6H12O6
• 5-C and 6-C sugars are generally in a ring
structure.
Starch and Cellulose
• 5-C and 6-C sugars are generally in a ring
structure.
• When two of these sugars bond, they form
disaccharides.
– ex. Maltose is a disaccharide of glucose
Starch and Cellulose
• Starch and cellulose are both polymers of glucose.
• However the glucose-glucose linkages are different.
Nucleic Acids
• The genetic information for all living things
• Two types of nucleic acids: DNA & RNA
– DNA: deoxyribonucleic acid
– RNA: ribonucleic acid
• Nucleic acids are polymers of nucleotides
• Nucleotides have 3 components:
– Phosphate group (PO43-)
– Nitrogenous base (adenine, thymine, guanine,
cytosine, uracil)
– Sugar (ribose or deoxyribose)
The repeating chain is of phosphate groups followed by
sugars where the nitrogenous base is bonded to the sugar.
-
DNA
• DNA is coiled into two strands forming a
helical structure.
• The two strands are complimentary
• The two strands are held together by
hydrogen bonding between –NH groups
and –C=O groups
• DNA is used by cells to code for proteins
Assignment:
• Handout: Ch.2 Project
• Read 2.7
– Pg. 136
• Practice #4, 6
• Section Questions #1, 11
• Chapter 2 Review
– Pg. 146-147
• #7, 10, 11a, 16, 19, 20