2. Answering “what”
Alcohol: An organic compound characterized by the
presence of a hydroxyl functional group, R-OH
Hydroxyl group: an OH-functional group
characteristic of alcohols.
3. Impacts on Society and Health
Society:
Every year roughly 5000 people under age of 21 die
because of alcohol related car accidents in USA.
Every 90 seconds, someone is injured from a drunk
driving accident.
Health:
Drinking alcohol leads to high blood pressure, stroke,
cancer (mouth, liver), and weak immune system.
It is also the main reason for change in mood/behaviour.
4. Naming Alcohols
(one hydroxyl group)
Use same naming scheme as hydrocarbons. For
example, methane for hydrocarbon with 1 carbon and
4 hydrogens. However, when you have one –OH group
instead of one hydrogen, you replace the “e” from
methane with “ol” For example, CH3OH would be
methanol.
If you have for than one carbon atoms, make sure to
identify where your –OH group is attached using
numercal numbers. For example, 2-propanol.
6. Polyalcohol
Poly means more than one, therefore polyalcohol
means an alcohol that contains more than one
hydroxyl functional group.
7. Naming Polyalcohol
Use the same naming scheme as hydrocarbons but add
“di”, “tri” etc. at the end followed by “ol”. For
example, if 2 hydrogens from two carbons of ethane
are replaced by –OH groups, the name would be “1,2ethanediol,” where “di” represents the number of –OH
groups present.
Make sure to use numerical number to identify where
the –OH group is attached in the parent chain.
9. Structure and Formula
The structure is same as hydrocarbons but you need to
attach right –OH group at right place. For
example, methanol’s structural formula will have one
Carbon attached to 3 hydrogens and one –OH group.
The chemical formula can be written by counting
number of C’s, H’s and O’s. It would be CH4O or
CH3OH.
Lets do an example.
10. Cyclic alcohols and naming
Cyclic alcohol: an alcohol that contains a cyclic ring.
To name them, you put “cyclo” after numerical number
if have any with the given name.
If there is any other branch such as “methyl,” put it
before everything else with numerical value to identify
its location.
OH
OH
OH
OH
1,2-cyclohexanediol
CH3
4-methyl-1,2-cyclohexanediol
11. Aromatic Alcohol/Naming
an alcohol that contains a benzene ring.
To name it, use prefix “hydroxy” with suffix “benzene”
Hydroxybenzene is also called phenol and it has one –
OH group attached to it.
If you have more than one –OH groups, use “di”, “tri”
etc before of “hydroxy” to indicate quantity of them
and use numerical value to show where they are
located. For example, 1,2-dihydroxybenzene
13. Physical Properties of Alcohols
By taking away one hydrogen and replacing it with
-OH, the main change which happens is the type of
molecule. It becomes polar from non polar. For
example, methane is non polar however, methanol is
polar.
In addition, hydrogen bonding occurs in hydroxyl
groups of molecules.
15. Boiling/Melting Point
Alcohols have high melting and boiling points as
compare to hydrocarbons because of the presence of
strong hydrogen bonding in it.
You need more energy to break that hydrogen bonding
and this explains high boiling/melting point.
Name
Formula
Boiling Point (C)
Methanol
CH3OH
65
Ethanol
C2H2OH
78
Name
Formula
Boiling Point (C)
Methane
CH4
-89
Ethane
C2H6
-164
16. Solubility (like dissolves like)
Alcohols are unique in a way that they can dissolve
both non-polar and polar substances.
This can be explained in terms of presence of –OH
which is polar and dissolves polar and same with
hydrocarbon but for non polar.
However, solubility of alcohols is determined by the
stronger of the two forces. (Dispersion for
hydrocarbon and hydrogen bonding for –OH)
Therefore, longer the chain, less soluble it is in water.
