1. Why does fruit smell so good?
Esters
Why does fruit smell so good?

2. Esters in fruits Smell Reactants needed Ester Banana or pear
Propan-1-ol + ethanoic acid
Pineapple
1-pentanol + ethanoic acid
Peach
Phenylmethanol + ethanoic acid
Rasberry
2-methylpropan-1-ol + methanoic acid
Apple
Pentyl pentanoate
Orange
Octyl ethanoate
Fruits contain mixtures of esters that give a distinct smell that is unique to the fruit.

3. Where does the bridging oxygen come from?
How can isotopic labelling of oxygen be used to check?
The bridging oxygen comes from the alcohol

4. Properties of esters Predict Boiling and melting point
Solubility in water
Smell
Volatility
VdW bonding and dipole-dipole interactions mean they have low mpts. and bpts.
There is no hydrogen bonding, therefore they are insoluble in water and other polar solvents (non-polar)
Distinct feature - they smell pleasant
They are volatile compounds.

5. How doe we get naturally occurring esters?+
Type of reaction?
+ 3 H2O
Type of reaction? Water is leaving so it is condensation.
Type of compound?

6. What else are esters used for?
Key question
What else are esters used for?

7. Reactions of esters
CH3COOCH2CH3 + H2O CH3COOCH2CH3 + NaOH CH2OOCR1 CHOOCR2 + CH3OH CH2OOCR3
Predict the products. Suggest a name for the reaction. Explain the chemistry!

8. Reactions of esters CH3COOCH2CH3 + H2O
Esters can be split up using boiling water
But even more effectively with the use of an acid
Therefore, this reaction is called acid hydrolysis
Predict the products. Suggest a name for the reaction. Explain the chemistry!

9. Reactions of esters CH3COOCH2CH3 + NaOH
Esters can also be split up using boiling KOH (aq)
This is even more efficient. Suggest why.
Therefore, this reaction is called base hydrolysis
Predict the products. Suggest a name for the reaction. Explain the chemistry!

10. SAPONIFICATION
Why fats and ash??

11. Soya bean & corn oil Olive oil Animal fats
Fatty acids form esters that are found in fats and oils. These are common fatty acids.
Oleic acid – Olive oil
Stearic acid – Animal fat
Linoleic acid – Soya bean and corn oil
Animal fats

12. A2427
26/05/2018
Saturated fat

13. Monounsaturated fat

14. Polyunsaturated fat

15. Hydrolysis of esters
When an ester is heated with an alkali, it is hydrolysed to.....?
CH3CH2COOCH2CH NaOH

16. Soap! Glycerol Hydrolysis of esters + 3 KOH
When an ester is boiled with an alkali.....?
Hydrolysis – because reverse of condensation as glycerol is formed. Also, OH is added.
Name of soap molecule / salt of COOH acid: potassium octadecanaoic acid +
Soap!
propane-1,2,3-triol
Glycerol

17. The reaction
propane-1,2,3-triol
sodium octadecanoate
Glycerol – used in cosmetics, in food and glue, also used in wine adding sweetness and viscosity!
Glycerol also has many uses. With its three O-H bonds, it can form hydrogen bonds easily and therefore attracts water

19. Reactions of esters
CH2OOCR1 CH3OOCR1 CH2OH CHOOCR2 + 3 CH3OH CH3OOCR2 + CHOH CH2OOCR3 CH3OOCR3 CH2OH
This reaction is called transesterification.
It produces bio-diesel!
Consider, the advantages.
Predict the products. Suggest a name for the reaction. Explain the chemistry!

20. Biodiesel formation catalysed by: react with: by-product: %yield:
Conditions:
Source:
main product:

21. Biodiesel formation catalysed by: NaOH
Methyl esters of long-chain fatty acids (triglycerides
react with:
Alcohol
by-product:
Glycerol
reversible
%yield:
98%
Conditions:
Low temp. (50◦C) & pressure
Source:
Vegetable oils: soya bean and rapeseed oils. Also, waste vegetable oils and discarded animal fats
main product:
New ester - biodiesel

22. Why bio-diesel?
Mixed with ____________ (___% biodiesel and ____% petrodiesel, which can be used in __________ ________
N____________
B_____________
C________ burning than petrodiesel
G__________ is a useful chemical
Saves ___________ ______
R_____________ sources

23. Why bio-diesel?
Mixed with petro-diesel (20% biodiesel and 80% petro-diesel, which can be used in diesel engines
Non-toxic
Biodegradable
Cleaner burning than petro-diesel
Glycerol is a useful chemical
Saves crude oil
Renewable sources

24. How could polyethylene terephthalate (PET) polymer be made?
Polyesters
How could polyethylene terephthalate (PET) polymer be made?

25. strong acid or specific enzyme
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Polyesters
diacid
diol
diacid
diol
strong acid or specific enzyme
- H2O

26. strong acid or specific enzyme
26/05/2018
Polyesters
strong acid or specific enzyme

27. Use of polyesters

28. HW 1. Read up on and summarise
HSW Soaps and detergents (including cleaning action of soap)
HSW Biodiesel
HSW Margarine and low-fat spreads
HSW – Polyesters everyday and biological esters
2. Test corrections