Alcohols

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Group 7 Alcohols
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Today's Starter Quote
When one door closes, another opens but we often
look so long and so regretfully upon the closed
door that we do not see the one which has opened
for us.
Alexander Graham Bell
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The simple way to think of alcohols is that there
is a water molecule where the hydrogen at one of
the termini is replaced by a carbon chain. The
alcohol present in beverages is ethanol, which is
the mildest depressant and narcotic poison of all
alcohols. Other alcohols magnify this effect and
are often added to ethanol in the lab to make it
unpalatable.
The addition of the OH group will drastically
change the properties of the related hydrocarbon.
This is due to the polarity of the molecule from
a non-polar hydrocarbon, as well as the
possibility of forming stable hydrogen bonds.
Ethane is non-polar Mild intermolecular forces
are easily broken
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Ethanol is polar and will have a s H terminus at
the OH group and a s oxygen atom adjacent to
it. Water will have a smiliar structure, however
due to its smaller size the molecule is more
polarized. These s and s ends are attracted
to one another in solution. This creates a very
strong network of hydrogen bonds. These networks
are significantly more difficult to break.
(www.elmhurst.edu, 2010)
The result?
The boiling point of ethane is 89 C, while
ethanol will boil at 78 C!
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In the IUPAC naming system, the OH functional
group changes the suffix from 'ane' to 'anol' at
the ending of the chain. The parent alkane is
the longest chain that contains that OH group.
CH3OH methanol Highly toxic, leading to blindness and death
CH3CH2OH ethanol Used in beverages, vanishes, lacquers and perfumes
CH3CH2CH2OH 1-propanol Solvent for waxes, found in brake fluid
CH3CH(OH)CH3 2-propanol (ispropanol, rubbing alcohol) Used in the manufacture of gums, oils and acetone
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Classification of alcohols Alcohols are
categorized based on the type of carbon that they
are attached to. Since carbon atoms have 4
bonds, the atom that has the OH can be attached
to 1,2 or 3 alkyl groups as well. This creates
primary, secondary and tertiary alcohols
respectively. The classification is important
for the types of reactions that each will undergo
because the products are determined by the
availability of H atoms in key positions.
CH3CH2CH2CH2(OH) 1- butanol
primary alcohol CH3CH2CH(OH)CH3 2-butanol
secondary alcohol CH3C(CH3)(OH)CH3 2-methyl-
2-butanol tertiary alcohol
The Lucas test will allow us to determine the
identity of each alcohol. The 3 alcohol reacts
instantly, the 2 alcohol reacts slowly (6
minutes) and the 1 alcohol will not react.
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Creating Alcohols Making Aldehydes and
Ketones A hydration reaction is an addition
reaction that adds the two components of water
across a unit of unsaturation. The reaction
often requires acid as a catalyst to break the
water moecule into H and OH-. The reaction may
occur as H2SO4 Propene water
--gt 2-propanol The reverse reaction is an
elimination (dehydration) reaction

• Markovnikovs rule the rich get richer
• When adding a substance such as water to an
  unsaturated hydrocarbon. The hydrogen will add to
  the carbon which already has more carbons. This
  is why in the example above 2-propanol is formed
  much more readily than 1-propanol. Another
  example would include
• 1-butene hydrogen bromide 1-bromobutane