1. CHAPTER 2: REACTIONS OF ORGANIC COMPOUNDS

2. MAIN TYPES OF REACTIONS in Organic Chem
I wonder why she wrote it in Japanese
Look! I think she’s using it to blow her nose
Whew! That was easy! 
She called it a Blood Bath!
Addition
Substitution
Elimination
Oxidation
Reduction
Condensation
Hydrolysis
Combustion
Types of Substitution Reactions

3. 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 alkane
To recognize: Two reactants make 1 product
LOOK FOR: check if C atoms in product(s) are bonded to more atoms than C atoms in reactant

4. 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)

5. EXAMPLES: Addition Reactions1) 2)

6. ADDITION REACTIONS: ALKENES
Symmetrical molecule reacts with asymmetrical molecule to give one product.
Symmetrical
Asymmetrical

7. Which product is favoured ?
RULES FOR ADDITION
Two asymmetrical molecules react to give two products.
Example:
Which product is favoured ? + or
Asymmetrical
Asymmetrical

8. “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
2-bromobutane
Major product +
Minor Product
1-bromobutane

9. ADDITION REACTIONS: ALKYNES
Also follow Markovnikov’s rule when asymmetrical
**if in excess
1,1,2,2-tetrabromopropane
Asymmetrical

10. ADDITION REACTIONS: ALKYNES
May occur as two addition reactions: +
First product would be the only product if reacted with limited amount of bromine. +

11. 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.
LOOK FOR:
Two compounds react to form two different compounds
Carbon atoms are bonded to the same number of atoms in product and reactant
2-bromobutane
2-butanamine

12. 2) SUBSTITUTION REACTION
1) CH3CH2-OH + HI CH3CH2-I + H2O 2) 3)
ethanol
iodoethane
Alcohols and haloalkanes undergo substitution reactions relatively easily
Haloalkanes also react with bases to undergo elimination reactions
Thus, hard to control reactions of haloalkanes with bases
For the purposes of our course:
OH– = substitution reaction
NaOCH2CH3 = elimination reaction
Alkanes also undergo substitution reactions
Alkanes are relatively unreactive, thus a lot of energy is required (UV light) to catalyze rxn
If enough of the halogen is present, a mix of organic compounds forms  example #3
Ultimately, because of the mix of products, this process is not used to produce haloalkanes

13. SUBSTITUTION REACTION Aromatics
Aromatics can only undergo substitution reactions

14. SUBSTITUTION REACTION Alcohols
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)

15. 3) ELIMINATION REACTION
atoms are removed form a molecule to form double bonds.
Reverse of addition
To recognize: One reactant breaks into two products
LOOK FOR: check if C atoms in product(s) are bonded to less atoms than C atoms in reactant

16. ELIMINATION REACTION: Alcohol
undergo elimination when heated in presence of strong acids, for example: H2SO4
Example:

17. ELIMINATION REACTION: Alkyl Halides
Undergo elimination to produce alkenes
Bromoethane ethene hydrobromic acid

18. opposite of Markovnikov’s Rule
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

19. Elimination
(major product) (minor product)

20. 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…

21. 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
Some oxidation reactions can also be classified as elimination reactions

22. 4) OXIDATION: Alcohol Alcohol oxidation can form an aldehyde or ketone
Primary Alcohol
Secondary Alcohol
Tertiary Alcohols do not oxidize

23. 4) OXIDATION: Aldehyde
Aldehydes undergo oxidation to produce carboxylic acid
Example:

24. 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
Some reduction reactions can also be classified as addition reactions
Lithium aluminium hydride
(hydrogen over a platinum catalyst)

25. 5) REDUCTION: Alkene

26. 5) REDUCTION: Aldehyde/Ketone
Aldehyde or ketone
Reducing
agent
alcohol

27. 6) CONDENSATION Water is usually produced in this reaction
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
LOOK FOR: Hydroxyl group from one molecule and a hydrogen atom from a second molecule being removed, and water being produced
Flavours and smells of fruits and spices are due to ester compounds

28. Condensation
carboxylic amine amide water acid

29. 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
LOOK FOR: a large molecule containing an ester or amide reacting with water to produce to smaller molecules  example #1
Both the condensation reaction and hydrolysis reaction are catalyzed by acid
1-propanol

30. 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:
Complete combustion: an excess of oxygen reacts with a hydrocarbon and produces carbon dioxide and water vapour, and releases energy
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

31. Combustion Example #1 CxHy + O2(g)  CO2(g) + H2O(g) + energy
HC + O2(g)  C(s) + CO(g) + CO2(g) + H2O(g) + energy

32. 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

33. POLYMERS can be synthetic or natural Synthetic polymers
man made polymer like plastics and polyester
Natural polymers
found in nature like glucose
and silk

34. ADDITION Polymerization
Monomers added together through multiple addition reactions
Examples:
Examples Pg 83: Table 2.1

35. 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