sch4u unit 1 organic chemistry. organic chemistry definition: the chemistry of carbon compounds must...

SCH4UUnit 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 AlkanesThe AlkenesThe AlkynesThe Aromatics

Naming Hydrocarbons

# of Carbons

123456789

10

Prefix

MethEth

PropButPentHexHeptOctNonDec

C-C

aneaneaneaneaneaneaneaneaneane

C C

yneyneyneyneyneyneyneyneyne

C=C

eneeneeneeneeneeneeneeneene

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

C

C

C

C

C

CH

H

H

H

H

H

H

H

H

H

H

HH

H

Methane• Simplest alkane

• Main component of natural gas

• Contributing green house gas

• Used as fuel

CHH

H

H

Ethane Propane• Second most simple

alkane• Minor ingredient of

natural gas

• Also known as bottled gas

• Found in natural gas, but separately for commercial purposes

C C

H

H

H

H

H

H

C C

H

H

H

H

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?

C

H

H

H

C

H

H

C

H

H

HC

H

H

C

H

H

H

C

H

C

HCH

H

HH

H

Question #1: Can you draw:

4-tert-butyl-4-isobutyl-5-n-butyl-5-sec-butylnonane?

• 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

Higher Alkanes

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 C2H6 -89

Propane C3H8 -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• Simplest member if the

alkene family, also called ethylene

• Most important commercial organic chemical

• U.S. production over 20 billion kg, more than have is used in the production of polyethylene, one of the most familiar plastics.

C C

H

H

H

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?

C

H

H

C

H

C

H

H

HC

H

H

C

H

H

H

C

H

C

H

H

HC

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

C C HH

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

C

H

H

H

C C

H

H

HCC

HC C

H

H

HC

H

H

Hydrocarbon Comparison

C C

H

H

H

H

H

H

C

H

H

C CH

H

H

H

H

C

HC C H

H

H

H

C

propane propene 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)

• Hydrogenation – addition of hydrogen (H2)

H

H H

H

Br Br BrBr

H

H

H

H

++ →→20oC

H H ++ H H →→H

H

H H

H

Hcatalyst

Heat, pressure2

Reactions of Alkenes and Alkynes

• Hydrohalogenation – addition of a hydrogen halide

• Hydration – addition of water

H

H

H

HH

H

BrH

H

H H H

H

H

H

H

H

HH

H

OH2

OHH

H

H H H

H

H

++

++

→→

→→H2SO4

20oCH-Br

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 Carboxylic AcidsEthers KetonesAldehydesEstersAmines

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

Methanol

• important solvent

• 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

COH

H

H

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

C C

H

OH

H

H

H

H

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

C C

H

H

H

H

H

H

C

H

OH

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

C C

OH

H

H

HO

H

H

C

H

OH

Ethers

• Extremely flammable

• Anesthetic properties

• Diethyl ether most common ether to medical personal

• 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

C C

H

O

H

H

H

H

CC

H

H

H

H

H

Aldehydes

• Formaldehyde is the simplest and best known

• When dissolved in water, it is used as a germicide, disinfectant, and preservative

• Used to preserve tissue

CHH

O

How do you make an aldehyde starting from an alcohol?

Do you need a primary, secondary or tertiary alcohol?

Ketones• Propanone, also known as

acetone is the simplest ketone

• 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.

C C

H

H

H

H

H

H

C

O

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

COH

O

H

Butanoic acid

Esters

• Quite fragrant even when dilute

• Many have fruity odours and tastes

• Used in flavourings for candies, as well as ingredients in perfume

C

H

H

OC

H

H

H

C

O

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

C

H

H

C

H

H

C

H

HC

H

HN

H

HN

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– forms a highly ordered

arrangement, resulting in a rigid material

– used to make toys, bottle caps, plumbing pipes

• Low Density Polyethylene– 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