CHAPTER 2: REACTIONS OF

ORGANIC COMPOUNDS

1) Addition2) Substitution3) Elimination4) Oxidation5) Reduction6) Condensatio

n7) Hydrolysis8) Combustion

Types of Substitution Reactions

She called it a Blood Bath!

I wonder why she wrote it in Japanese

Look! I think she’s using it to blow her nose

Whew! That was easy!

MAIN TYPES OF REACTIONS in Organic Chem

1) ADDITION REACTION •Atoms added to a double or triple bond•Alkene or Alkyne undergoes addition reaction to break a double or triple bond•Example:

Reactant XY added to alkene makes alkaneTo recognize: Two reactants make 1 product

1) ADDITION REACTIONS

Common atoms that can be added to an alkene or alkyne

•H and OH (from H2O )

•H and X (from H-X) where X= Cl , Br, or I

•X and X from (X2) where X= Cl , Br, or I

•H and H (from H2)

EXAMPLES: Addition Reactions

1)

2)

ADDITION REACTIONS: ALKENES

•Symmetrical molecule reacts with asymmetrical molecule to give one product.

Symmetrical Asymmetrical

RULES FOR ADDITION• Two asymmetrical molecules

react to give two products.Example:

Which product is favoured ?

Asymmetrical

Asymmetrical

or+

Major product

Minor Product

2-bromobutane

1-bromobutane

“MARKOVNIKOV’S” Rule• "the rich get richer"• The carbon atom with the largest number of

carbon atoms gets the X (halogen) or OH bind to it

• Therefore 2- bromobutane is favoured

+

ADDITION REACTIONS: ALKYNES

• Also follow Markovnikov’s rule when asymmetrical

1,1,2,2-tetrabromopropane

Asymmetrical

ADDITION REACTIONS: ALKYNES

• May occur as two addition reactions:

+

+

2) SUBSTITUTION REACTION• A hydrogen atom or functional group is

replaced by a different atom or functional group

• To recognize: two compounds react to form two products.

2-butanamine2-bromobutane

2) SUBSTITUTION REACTION

1) CH3CH2-OH + HI CH3CH2-I + H2O

2)

3)

ethanol iodoethane

SUBSTITUTION REACTIONAromatics

• Aromatics can only undergo substitution reactions

SUBSTITUTION REACTIONAlcohols

• Halogens in HCl, HBr or HI can substitute the OH group of alcohol or the reverse.

• For Ex: CH3-CH2-OH + HCl CH3-CH2Cl +

H2O

• The reverse reaction:CH3-CH2Cl + OH- CH3-CH2-OH + Cl-

(from water)

3) ELIMINATION REACTION• atoms are removed form a molecule to

form double bonds.• Reverse of addition• To recognize: One reactant breaks into

two products

ELIMINATION REACTION:Alcohol

• undergo elimination when heated in presence of strong acids, for example: H2SO4

Example:

ELIMINATION REACTION:Alkyl Halides

• Undergo elimination to produce alkenes

Bromoethane ethene hydrobromic acid

Elimination

• If an asymmetrical molecule undergoes an elimination reaction, constitutional isomers can form example #3

• General rule: H atom most likely to be removed from C atom with most C-C bonds

• “The poor get poorer!” – opposite of Markovnikov’s Rule

– Called Zaitsev’s rule

Elimination

(major product)

(minor product)

4) OXIDATION & 5) REDUCTION REACTIONS

• Change in the number of H or O atoms bonded to C

• Always occur together• One reactant is oxidized while the

other is reduced• For now, lets focus on reactant

only…

4) OXIDATION• Carbon atom forces more

bonds to Oxygen or less to Hydrogen

• For example: formation of C=O bond

• Occurs in presence of oxidizing agents [O] such as KMnO4, K2Cr2O7, and O3

• For now, focus on organic reactant only

4) OXIDATION: Alcohol

• Alcohol oxidation can form an aldehyde or ketone

Primary Alcohol

Secondary Alcohol

Tertiary Alcohols do not oxidize

4) OXIDATION: Aldehyde

• Aldehydes undergo oxidation to produce carboxylic acid

Example:

5) REDUCTION REACTION

• Carbon atom forms fewer bonds to Oxygen or more bonds to Hydrogen

• Aldehydes, ketones and carboxyliic acids can be “reduced” to alcohols

• Alkenes and alkynes can be reduced to become alkanes

• Occurs in the presence of reducing agents such as LiAlH4, and H2/Pt

where Hydrogen [H] is added

5) REDUCTION:Alkene

5) REDUCTION:Aldehyde/Ketone

+ [H]

O

R1

C

R2

H

O

R1 C R2

HAldehyde or ketone Reducingagent

alcohol

6) CONDENSATION• two molecules combine to form a single, bigger

molecule. • Water is usually produced in this reaction • A carboxylic acid and alcohol can condense to

form an ester– called “ esterification”

• A carboxylic acid and amine can condense to form an amide

Condensation

carboxylic amine amide wateracid

R1

O

O

C

H

+R3

R2

NH + OHH

R1

O

C

R3

R2

N

7) HYDROLYSIS• water adds to a bond splitting it into two • Reverse of a condensation reaction• Water can add to an ester or amide bond• Ester + water makes a carboxylic acid and

alcohol• Amide + water makes a carboxylic acid and

amine

1-propanol

8) Combustion

• Type of reaction in which a compound reacts with oxygen to produce the oxides of elements that make up the compound

• 2 types:1) Complete combustion: an excess of

oxygen reacts with a hydrocarbon and produces carbon dioxide and water vapour, and releases energy

2) Incomplete combustion: reaction that occurs when insufficient oxygen is present; all elements in the fuel will not combine with oxygen to the greatest extent possible

Combustion

• Example #1CxHy + O2(g) CO2(g) + H2O(g)

+ energy

• Example #2HC + O2(g) C(s) + CO(g) + CO2(g) + H2O(g) +

energy

POLYMERS

• very long molecules made by linking small molecules called monomers

• Example: -PET(Polyethylene terephthalate ) polymers

- Plastics are polymers that can be heated and moulded into specific shapes and forms

-Polyethene is made from monomer of

POLYMERS

can be synthetic or natural• Synthetic polymers

– man made polymer like plastics and polyester

• Natural polymers– found in nature like glucose

and silk

ADDITION Polymerization• Monomers added together through multiple

addition reactions• Examples:

• Examples Pg 83: Table 2.1

CONDENSATION Polymerization

• monomers are joined together by the formation of ester or amide bond

• Water created as a side product• Example:

• Polyesters contain many ester bonds• Nylon (polyamide) contains many amide bonds