Carboxylic AcidsRobert BoomerBronte RichardsonJacob BardwellJeff Polasz

Structure and Functional Groups: Slides 3-5

Nomenclature: Slides 6-9Properties/Uses: Slides 10-12Examples: Slides 13-14Reactions: Slides 15-20

Structure & Functional GroupFunctional 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 GroupDifferences:

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?

NomenclatureStep 1: Identify longest carbon chain (gives you

prefix) Begin at carbon that has the hydroxide

and oxygen atoms bonded to itStep 2: Determine whether there are any

double or triple bonds present

NomenclatureStep 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 chainREMINDER: CARBOXYL GROUP ALWAYS TAKE PRESIDENCE WHEN NAMING A MOLECULE

Nomenclature Practice Name the following carboxylic acids:

Nomenclature PracticeDraw the following carboxylic acids: 3-Methylbutanoic Acid 4-chloro-2-methyl-3-pentynoic acid

PropertiesAcidity 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

PropertiesExample 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.

PropertiesSolubility 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.

PropertiesMelting/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

PropertiesExample 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 Lactic AcidAscorbic acid (Vitamin C)

Tartaric acidFormic 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?

ReactionsControlled 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

ReactionsFormation of an aldehyde:

Formation of a carboxylic acid:

ReactionsExample 1: Methanoic Acid

Methanal Methanoic Acid(Formaldehyde) (Formic Acid)

+ (O)

ReactionsExample 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