Types of Organic Reactions

Tom Nowak

Cedar House School

G12 Organic Chemistry

Organic Chemistry ReactionsBOLD ONLY = examinable

Addition Substitution Combustion Elimination Esterification Fermentation Polymerization (Addition & Dehydration) Saponification

Addition

Addition reactions occur when atoms are added to an unsaturated molecule (an alkene or alkyne)

+H H

H H

Organic Chemistry Reactions

Addition

1) Define saturated and unsaturated, offer structural formula example of each

2) Explain why unsaturated must be the reactant

Substitution

Substitution reactions occur when one type of atom replaces a hydrogen atom in a saturated (yet not necessary) molecule

+

+H

Cl

ClH-Cl

Organic Chemistry Reactions

Substitution

Give your own example of substitution.

Combustion

Combustion refers to the reaction of a compound with oxygen to produce energy (an exothermic reaction).

There are two types:

Complete combustion - in which CO2 is produced.

Incomplete combustion - in which CO is produced.

Water is also produced in combustion reactions

Combustion is EXOTHERMIC turning chemical potential energy into heat energy

Example of complete combustion:

CH4 + 2 O2 CO2 + 2 H2O

Example of incomplete combustion:

2 CH4 + 3 O2 2 CO + 4 H2O

In addition to the differences in the products, what other difference can you detect between complete and incomplete combustion?

The difference in the two types of combustion involves the ratio of oxygen to fuel:

Complete Combustion:

CH4 + 2 O2 CO2 + 2 H2O

The coefficients tell us that we need 2 oxygen molecules for every 1 methane molecule for complete combustion.

Incomplete combustion:

2 CH4 + 3 O2 2 CO + 4 H2O

In incomplete combustion the ratio is 3 oxygens for every 2 methane molecules

Combustion final

• Explain why fossil fuels contain lots of Chemical potential energy• Explain how fossil fuels release this potential energy With Combustion as thermal heat energy• Explain how fossil fuel engine utilize this heat energy to Do work• Explain how a larger volume engine (liters) is usually More ”powerful”

Elimination

An elimination reaction occurs when 2 substituents or functional groups are REMOVED from a molecule.Elimination can be seen as the reverse of additionLG = leaving group, general term for substituent that is Usually Electron donating/negative (anion) or neutral For example = halides, oxides, other hydrocarbons

H-C-C-LG C=C + H-LG

Organic Chemistry Reactions

Elimination

Describe elimination of alcohol

Describe elimination of alkyl halide

Elimination:Dehydration of alcohol

Elimination: Dehydrohalogenation

CH2Cl – CH2Cl CH2=CHCl + HCl

Elimination: Cracking of hydrocarbons (thermal) =forms radicals &random products

Elimination: Cracking of hydrocarbons (catalytic)= more reliable carbon products

Esterification

+

+

Acid Alcohol

Ester Water

Organic Chemistry Reactions

Esterification

Write an equation to prepare an ester

Identify the reactants from this product

FermentationIn the fermentation reaction a sugar is broken down into ethanol and carbon dioxide

2 + 2

Glucose Ethanol Carbon dioxide

Xymase

Xymase is an enzyme (a biological catalyst)

Polymerization is the process by which a numberof small molecules (monomers) are hooked together to form a larger molecule (polymer). This is like forminga train from a bunch of individual railroad cars.

Monomers

Polymer

Addition Polymerization

In this type of polymerization, the links between the monomers are formed by the breaking of double bonds.

n

Ethene Polyethylene

Addition polymerization always involves unsaturated compounds

Condensation Polymerization

In this type of polymerization, two molecules react together to form a larger molecule plus some other product (sometimes water).

n

monomer Polymer

In this case, the polymer is held together by ether linkages.

+ H2O

Organic Chemistry Reactions

Esterification Addition Substitution Fermentation Polymerization (Addition & Dehydration) Saponification

Saponification

In saponification, a fat reacts with a strong base to form glycerol and three soap molecules (long non-polar molecules with a polar end)

+ +

FatStrong base

Glycerol Soap

R - represents a long chain of C and H atoms