9. Classification of alcohols
1.
Primary alcohol: contains one carbon
atom directly attached to the carbon that
contains the hydroxyl group, e.g.
propan-1-ol
10. 2. Secondary alcohol: contains two carbon
atoms directly attached to the carbon that
contains the hydroxyl group, e.g.
propan-2-ol
12. Physical properties
Solubility of methanol in
(i) cyclohexane – not very soluble
methanol is polar cyclohexane is not
(ii) water - completely soluble
because it is polar.
As alcohol molecule gets bigger the polar
part becomes less significant so the alcohol
becomes less soluble in water and more
soluble in cyclohexane
13. Butan-1-ol is
– (i) soluble in cyclohexane
– (ii) not very soluble in water
The
polar OH group is becoming less
significant as the molecule gets bigger
14. Comparison with water
Both
have polar OH groups
Alcohols have a non-polar part
Both form hydrogen bonds between their
molecules
Water is more polar and has a greater
capacity to form hydrogen bonds and so has
a higher boiling point than methanol or
ethanol
15. Methanol
Methanol: is toxic (can cause blindness, insanity and
death)
It is added to industrial alcohol to prevent people
drinking it. This mixture is called methylated spirits.
The methanol acts as a denaturing agent – it
renders a substance unfit for purpose without
destroying the usefulness or applications of the
substance. A purple dye is often added as a warning.
16. Ethanol
Ethanol: is produced by fermentation. Fruits provide
the sugar and yeast may need to be added.
The enzyme zymase in yeast catalyses the reaction.
C6H12O6
2C2H5OH
+
2CO2
18. Ethanol
To
produce drinks of higher alcohol
concentration the fermented liquids must be
distilled.
Spirits
(whiskey, brandy, gin, vodka) contain
40% alcohol.
