Organic Chemistry Carboxylic Acids Physical Properties

1. Carboxylic Acids
Week 1-2

2. Contents
Introduction: Learning Objectives
Carboxylic Acids: Basics
Structure & Nomenclature
Practice
Physical Properties
2
Practice

3. Introduction: Learning Objectives
2. Understand how to draw structural and
displayed formulae for Carboxylic Acids
3. Predict physical properties of
compounds with Ionic Bond
1. Know that Carboxylic acids contain the
functional group -COOH

4. Carboxylic Acids: Basics
• Carbon (C) atom is bonded to an oxygen (O) atom by a double bond and to a hydroxyl group (―OH)
by a single bond.
Carbonyl Hydroxyl
Carboxyl Group
Why Carboxylic Acids?

5. Why Carboxylic Acids?
The following points will state other significant uses of carboxylic acids:
1.Manufacturing of soaps need higher fatty acids. Soaps are generally sodium or potassium
salts of higher fatty acids such as stearic acid.
2.Food industry uses many organic acids for the production of soft drinks, food products etc.
For example, acetic acid is used in making vinegar.
3.In pharmaceutical industry organic acids are used in many drugs such as aspirin,
phenacetin etc.
4.Acetic acids are often used as a coagulant in the manufacturing of rubber.
5.Organic acids find huge application in making dye stuff, perfumes and rayon.

6. Structure & Nomenclature

7. Structure & Nomenclature
• Rules:
1. Choose Parent Chain  Longest Chain
2. –COOH Group is always given the #1 location position in numbering
3. The –e ending is removed from the name of the parent chain and is
replaced -anoic acid.
2-methyl pentanoic acid 2,2 dimethyl butanoic acid 3-hydroxy butanoic acid
Note: Carboxylic acids are given
the highest nomenclature priority
Note:  CH3 CH3

8. Practice

9. Acidity Solubility Boiling Point
Physical Properties

10. Acidity
Carboxylic Acids => Acids => Acidic Properties
Acidity
An acid is any compound that donates a hydrogen ion, H+ (also called a proton). (Mineral Acids: HCl, HNO3,
H2SO4, H3PO4)
H Cl
H Cl
H Cl
H Cl
Acid to water
H+
H+
H+
H+
Cl -
Cl -
Cl -
Cl -
HCl  Cl - + H+ (100% Ionization)
Important Note: Stronger the ionization, acidity increases

11. Acidity
CH3COOH ↔ CH3COO- + H+
Ionization is not complete, thus less than 100%,  weaker than mineral acids
Reversible
C2H5COOH ↔ C2H5COO- + H+
C3H7COOH ↔ C3H7COO- + H+
Solubility

12. Solubility
Similar to that of alcohols, aldehydes, and ketones.
Acids with fewer than about five carbons dissolve in water; those with a higher molecular
weight are insoluble owing to the larger hydrocarbon portion, which is hydrophobic.

13. Boiling
Point
Carboxylic acids have much higher boiling points than hydrocarbons, alcohols, ethers, aldehydes, or
ketones of similar molecular weight.
Even the simplest carboxylic acid, formic acid, boils at 101 °C (214 °F), which is considerably higher
than the boiling point of ethanol (ethyl alcohol), C2H5OH, which boils at 78.5 °C (173 °F), although
the two have nearly identical molecular weights.
The difference is that two molecules of a carboxylic acid form two hydrogen bonds with each other
(two alcohol molecules can only form one).
2 Hydrogen Bonds