1. Tetrahedral
Carbons
C3H8

2. C=O
Planar
Carbon
CH3CHO

3. Addition Reactions
Planar Tetrahedral

4. 2 reactants making 1 product
Addition as something will be added across the double bond

6. Double bonds are stronger than single bonds – so why do addition reactions happen so easily?
Energy requird to break double bond
Energy released when two single bonds formed
Net release of energy meaning products more stable than reactants
Need to know reaction with H2 and H2O
Need to know mechanism with Br2, Cl2 and HCl

7. Bromine Mechanism Br – Br bond becomes polarised
Heterolytic fission occurs
Carbonium ion formation
Br+ adds on to ethene, cyclic structure formed
Attack on carbonium ion by bromide ion
Final product is 1,2-dibromoethane
Same mechanism for HCl and Cl2, but no ring structure, neither Cl nor H big enough to (stretch across)

8. Ionic Addition – Evidence for
Called ionic addition as ions add across double bond and also carbonium ion formed
Can be proven by adding bromine in water in presence of sodium chloride NaCl – 2 forms of evidence
Chloride ion attacks carbonium ion forming bromo-2-chloroethane
Water molecule attacks carbonium ion forming 2-bromoethanol

9. Uses Must know uses for the products of the five reactions
Additive
Product and Use H2
Ethane - fuel
HCl
Chloroethane – solvent
H2O
Ethanol – solvent / additive for petrol
Cl2
1,2 – dichloroethane – used to make vinyl chloride – PVC
Br2
1,2 – dibromoethane – pesticide, insecticide
Must know uses for the products of the five reactions
Must be able to discuss hydrogenation of oils

10. Dairy products like butter and cream are mainly saturated – no double or triple bonds
Margarine invented as alternative
Edible oils are esters of long chain unsaturated carboxylic acids – lots of C=C
Less damaging to health
But oils not much use for spreading on bread
But by adding H2 across some of the double bonds, oils could be changed into soft solids with low melting points – margarine
Margarine is easier to spread than butter (lower melting point)
It also contains less saturated fats that people worry about
By controlling degree of H2 added, margarine can be made as soft or as hard as needed

11. Polymers
Long chain molecules made by joining together (adding) many small molecules
They consist of a repeating structure and can have a molecular mass of several thousand
monomer + monomer +…. polymer
Commonly known as plastics
Examples include polythene, poly(propene), PVC, polyester, etc
Draw out some structures from the book into your notes copy (pg 369/370).

12. Substitution Reactions
Tetrahedral Tetrahedral
Planar Planar

14. Need to know same mechanism for ethane
Chlorine Mechanism
Initiation
UV light breaks down Cl2 into 2 Cl atoms
Propagation
A Cl atom attacks the CH4molecule to form HCl and a methyl free radical
A methyl free radical attacks a Cl2 molecule to form ClCH3 and a Cl atom
These two processes repeat continuously in a chain reaction
Termination
Free radicals and atoms combine with each other to stop reaction
Need to know same mechanism for ethane

15. Free Radicals – Evidence for
Called free radical substitution
2 forms of evidence
Small amounts of ethane are found among the products – only can be formed when 2 methyl radicals bond
If tetramethyl lead is added to reaction mixture, rate of reaction increased – Pb(CH3)4 feeds methyl radicals into system, speeding up propagation
(Butane and tetraethyl lead when accounting for ethane mechanism)

16. Esterification Acid + Alcohol Ester + Water
Ethanoic acid + Ethanol Ethyl ethanoate + water
H2O
In the presence of heat and concentrated sulphuric acid

17. Hydrolysis of Esters Ester + Water Acid + Alcohol
Reverse of Esterification
Called hydrolysis because ester REACTING WITH water
Similar reaction happens with a base instead of water

18. Ester + Base Salt + Alcohol
Called base hydrolysis of esters or saponification
Soaps are long chain potassium / sodium salts of carboxylic acids -- mandatory exp
+ NaOH +

19. Elimination Reaction
Tetrahedral Planar

21. Redox Reaction
Tetrahedral Planar
Planar Tetrahedral

22. Redox Reactions
Recall from Chapter 15 that oxidation can be described by the gain of Oxygen
Recall from Chapter 15 that reduction can be described by the gain of Hydrogen
Therefore oxidation can also be described as the loss of hydrogen – dehydrogenation

23. Primary Alcohols
Primary alcohols are oxidised to the corresponding aldehydes, which can be further oxidised to the corresponding carboxylic acids.
Loss of H2
Gain of O
K2Cr2O7 crystals turn from orange to green during process

24. Secondary Alcohols
Secondary alcohols are oxidised to ketones, and no further
Loss of H2

25. Reductions
Carboxylic acids are reduced to the corresponding aldehydes and further to the corresponding alcohols – (opposite of oxidation)
Loss of O
Gain of H2

26. Facts Word aldehydes comes from alcohol dehydrogenation
Oxidation of ethanol to ethanoic acid causes problems for wine producers – open wine can turn to dilute vinegar!
Breathalyser test uses K2Cr2O7 crystals, extent to which the crystals turn green is a measure of concentration of alcohol in blood

27. tetrahedral
planar

28. (a) Tetrahedral Tetrahedral
Reactions as Acids
(a) Tetrahedral Tetrahedral
(b) Planar Planar

29. Acidic Nature Of Carboxylic Acids
If something willingly loses a H+, than it is considered to be an acid
OH group is polar enough that a H+ can be lost
Alcohols have low tendency to lose H+, lower than water. Only react with very reactive metals
Carboxylic Acids on the other hand are much more reactive
Due to inductive effect in COOH group, the end H is very easily lost
Carboxylate ion formed is very stable (electron delocalisation as with benzene)
This stability is driving force behind losing of H+
Reacts as normal acid but much weaker than common lab acids

30. b) R e
action of A c
ids
Magnesium Salt + H y
drogen Mg A
cid

31. Ester Ketones Alcohol Aldehyde Acid Alkenes Alkanes Polymers
HCl H 2
/Ni
Sodium Salt Cl
U.V. light
Ester
Sodium
Salt + A l
cohol Na
Acid
Alcohol
NaOH Al O 3
KEY
Addition Reactions
Substitution Reactions
Redox Reactions
Elimination Reactions
Reactions of Acids
Ketones H 2 O
Alcohol
Aldehyde
Acid
Oxidation
Reduction Na Cr 7
and H +
/Ni
Magnesium Salt
Sodium Salt Mg
NaOH CO 3
Chloroalkanes
Alkenes
Alkanes
Polymers
Reduction H 2
/Ni
Cl2
Br2
Bromoalkanes