Download Carboxylic Acids

Carboxylic
Acids
Robert Boomer
Bronte Richardson
Jacob Bardwell
Jeff Polasz
Structure
and Functional
Groups: Slides 3-5
Nomenclature: Slides 6-9
Properties/Uses: Slides 10-12
Examples: Slides 13-14
Reactions: Slides 15-20
Structure & Functional Group
Functional Group:
 Carboxylic acids contain a carbonyl
attached to a hydroxyl group; this is
called a carboxyl group
 Carboxyl group is defined by the double
bond between carbon and oxygen
 R represents the carbon chain
Structure & Functional Group
 They
are Brønsted-Lowry acids because
they are proton (H+) donors which makes
them more acidic than alcohol
 Acids with two or more carboxyl groups
are called dicarboxylic, tricarboxylic, etc.
Structure & Functional Group
Differences:
Quiz
 What
functional group do carboxylic
acids have?
 Why are carboxylic acids more acidic
than alcohol?
 What is the difference between a
carboxylic acid and a ketone?
Nomenclature
Step 1:
 Identify longest carbon chain (gives you
prefix)
 Begin at carbon that has the hydroxide
and oxygen atoms bonded to it
Step 2:
 Determine whether there are any double
or triple bonds present
Nomenclature
Step 3:
 Apply suffix –oic acid to the prefix determined
by parent chain
Step 4:
 Identify the presence of any branches (ethyl,
methyl, propyl, etc.)
 Identify and record at which branch each
meets the parent chain
REMINDER: CARBOXYL GROUP ALWAYS TAKE
PRESIDENCE WHEN NAMING A MOLECULE
Nomenclature Practice
Name the following carboxylic acids:
Nomenclature Practice
Draw the following carboxylic acids:
 3-Methylbutanoic Acid
 4-chloro-2-methyl-3-pentynoic acid
Properties
Acidity
 Given by the name, Carboxylic acids are
acidic. This is because of the transfer of
the hydrogen ion present in the -COOH
group, to a water molecule, ionizing the
acid molecule
Properties
Example 1:
𝑪𝑯𝟑𝑪𝑶𝑶𝑯+𝑯𝟐𝑶 ↔𝑪𝑯𝟑𝑪𝑶𝑶− +𝑯𝟑𝑶 −
(Above: Ethanoic acid, a weak acid)
 Carboxylic
acids are relatively weak
compared to other acids because they
do not fully dissociate to produce H+
cations however are still the most acidic
out of the organic functional groups.
Properties
Solubility
 The hydrogen bonds, as well as the presence
of a carbonyl group (-CO) both result in the
molecules being polar, preforming similar
solubility behaviour as alcohols.
 Carboxylic acids containing up to four
carbon atoms will mix with water in any
proportion, whereas larger hydrocarbon
chains are more likely to be insoluble because
they are more non-polar. However this means
they can react with organic bases to
produce organic salts.
Properties
Melting/Boiling Point
 Carboxylic acids have higher boiling
points than their parent alkanes due to
the fact that the carboxyl group has
increased intermolecular attractions from
the high polarity of the molecule
Properties
Example 2: Oxalic acid, similar to Ethanoic
acid, has 2 carbon atoms and unlike
Ethanoic acid, has 2 carboxyl groups. This
increases the boiling point considerably
because it is able to donate a proton twice,
doubling the size of the molecule and
increasing Vander Waal forces, therefore
the boiling point.
 Oxalic acid (189◦C)
Uses


Carboxylic acids are generally characterized
by their distinctive smell or sour/tangy taste.
They are found in citrus filled fruits such as
apples, rhubarb, grapes and other fruits with
high acidity
Carboxylic acids are also produced when an
alcohol is oxidized accordingly. This creates
the double bond between the oxygen,
creating the –COOH group. An example of
this is when red wine is oxidized to make red
wine vinegar, gaining the more sour taste.
Uses
 Carboxylic
acids are also very useful
when acting as precursors for producing
other compounds due to the fact that
they can undergo ionization, oxidization,
react in neutralization reactions with
alcohols and organic bases to form
biological compounds.
Common Carboxylic Acids
Citric Acid
Tartaric acid
Ascorbic acid
(Vitamin C)
Lactic Acid
Formic acid
(methanoic acid)
Quiz 2
 True
or False: Carboxylic acids are acidic
because of condensation.
 Which Organic Family do Carboxylic
acids have similar solubility as?
 True or False: Carboxylic acids have a
high boiling point.
 What do alcohols undergo to produce
Carboxylic acids?
Reactions
Controlled Oxidization (Preparation)
Conditions:
 Aqueous solutions
 Requires Catalyst: Usually K2Cr2O7 (Potassium
dichromate (VI))
 A carboxylic acid is formed from a controlled
oxidation of an aldehyde
 Mild oxidation  Aldehyde
 Further controlled oxidation  Carboxylic Acid
 Functional group: carboxyl group (One additional
O atom)
 Add an O to the H to make OH
Reactions
Formation of an aldehyde:
Formation of a carboxylic acid:
Reactions
Example 1: Methanoic Acid
+ (O) 
Methanal
(Formaldehyde)
Methanoic Acid
(Formic Acid)
Reactions
Example 2: Breathalyzer (Oxidation of
ethanol to acetic acid)
Ethanol + (O)  Ethanal (Acetaldehyde) +
(O)  Acetic Acid
+ Cr⁶⁺ (orange) 
+ Cr³⁺ (green)
Reactions



When measured volume of air containing
ethanol passes through breathalyzer tube,
ethanol is oxidized to acetaldehyde (ethanol)
then to acetic acid.
This process is accompanied by a reduction
of the chromate ion to its Cr³⁺ oxidation state.
The extent of the green colour down the
breathalyzer tube provides a measure of the
concentration of alcohol in the breath.
Reaction Worksheet