Introduction of
Homologous series: Alkanols Common name: AlcoholsGeneral Formula
CnH2n+1OH
or (R-OH)Functional Group - the hydroxyl group
-OH
IUPAC System of Naming
Choose the longest continuous carbon chain that contains the -OH group
The last letter -e of the corresponding alkane is changed to -ol
IUPAC System of Naming Alkanol:
Examples
CH3OH methanol
CH3CH2OH ethanol
CH3CH2CH2OH propan-1-ol
CH3CHCH3 propan-2-olOH
CH3CH2CH2CH2OH butan-1-ol
IUPAC System of Naming Alkanol:
e.g. Name the following compound
Answer : 2-methylpropan-2-ol
CH3
CH3 - C - CH3
OH
Manufacture of EthanolManufacture of Ethanol
There are 2 preparation methods:-
1. Ethanol prepared from hydration of ethene
2. Ethanol prepared from Fermentation of some sugar or starch containing food
Ethanol from ethene
Industrial ethanol is formed from ethene, a petroleum product.
The flow diagram for ethanol manufacture by direct hydration of ethene
Ethene
steam
Furnace ReactorCondensor
ethanol + water is formed
Ethanol from fermentation
Fermentation is the slow breakdown of large molecules to smaller molecules
by micro-organism.
The sources are used
Ethanol has been made by fermentation for several thousand years.
The raw material is some form of starch or sugar such as :
wheatwheat ricerice
potatoespotatoes grapesgrapesappleapple
&&
-Different Source can make different Alcoholic drinks.
Starch/Sugar sources Alcoholic drinkBarley BeerGrape Red/White wineBarley WhiskyGrape BrandyPotatoes VodkaWheat Gin
Micro-organisms used –– Yeast
Zymase is an enzyme present in yeast.Act as catalyst.Conditions: room temperature and pressure.Converts sugar to ethanol and CO2.
For example: Glucose C6H12O6 ,
C6H12O6 (aq) 2CH3CH2OH () 2CO2 (g)
glucose ethanol
CO2
How to obtain a max. concentration of ethanol from fermentation
The yeast is killed when the proportion of ethanol reaches about 15%.
To obtain a further concentration of the solution, fractional distillation is used.
Max. concentration of the distillate is about 96%.Pure ethanol (absolute ethanol) is obtained by
using CaO (drying agent) to removed the traces of the water.
1. Physical Uses
2. Chemical Uses
• Solvents• Beverage• Disinfectant
• Vinegar Synthesis• Ester Synthesis
3. Fuel • Gasohol (a mixtrue of ethanol and petrol
4. Preparation of ester and ethanoic acid
UsesA. Used as Solvent
A. Polar Group -OH
B. Non-Polar Group CH3CH2-
Water Soluble
Oil Soluble
Hence, Ethanol is Soluble in Both water and Oil
Because Ethanol (CH3CH2OH)contains :
Compare the solubility in water of alkane and alkene with that of alknaol?
Alkane and alkene have very low solubilities in watersince there is no polar group in their structuresbut only hydrocarbon chains, therefore they are only soluble in non-polar solvent.
UsesB. Used as Bervage
Hence, ethanol is used as Bervage
Because Ethanol (CH3CH2OH)contains :
Ethanol is used as bervage because of its GOOD TASTE Thinning of blood and less prone to heart disease PROVIDE A RELEX SENSE
Chemical UsesA. Used as Fuel
As much heat is given out from the above reaction, ethanol can be burnt as fuel
Because burning of Ethanol (CH3CH2OH)is highly exothermic
CH3CH2OH + 4 O2
3CO2 + 3 H2O
Ethanol can be used as Fuel for motor cars.
Advantage: - cleaner then burning petroleum.
Disadvantage:- it is less powerful than petrol
Gasohol is a mixture of ethanol and petrol
B. Used in preparation of Ester
The Ester (with sweet smell) formed can be used as a food flavoring, perfumes and cosmetics.
Because Ethanol (CH3CH2OH) react with Ethanoic Acid to form Ester
Chemical Uses
CH3CH2OH + CH3C OH
O
CH3C OCH2CH3
O
C. Used in synthesis of Vinegar
The Ethanoic acid formed is used as a main component in Vinegar.
Because Ethanol (CH3CH2OH) react with Oxidizing agent to form Ethanoic acid
CH3CH2OHCH3C OH
O
Chemical Uses
[O]
Effects of Alcoholic DrinksAll are poisonousMethanol (CH3OH) is toxic
All alcoholic drinks contain ethanolSmall amounts can help the thinning of blood
and less prone to heart disease, but
Large amounts is dangerous.Taken in large amount has an immediate bad
effect of mental and physical performance.
Effects of Alcoholic Drinks
It affects the normal functioning of the nervous system
Excessive drinking of alcohol over a long period of time, leads to damage of liver and loss of memory
People may become addicted to itMany health, family and social problems
are due to these alcoholics
RevisionRevision
The general formula of alkanol is
A. CnH2nOH
B. CnH2n+2OH
C. CnH2n+1OH
D. CnH2n-1OHD
C
B
A
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Introducing Alkanols
The general formula: CnH2n+1OH or ROH
The molecule consist of a functional group - the __________ group (-OH) joined to an _________ group (R-) .
RevisionRevision
hydroxylalkyl
2. Ethanol can be formed by two methods. They are
Equation:
CH2=CH2 + H2O C2H5OH
?Hydration of ethene ?
Fermentation of sugar or starch containing food
Equation:
C6H12O6(aq) CH3CH2OH (l) CO2 (g)
OR
The FIVE uses of Ethanol
1.
2.
3.
4.
5.
6. Use as disinfectant
Use as Solvent
Use as Bervage
Use as Fuel
Use in preparation of Ester
Use in synthesis of Vinegar