The slides contains Introduction to Isomerism Topic, classification of Isomers,Physical Properties of Alcohols. It contains examples and questions.

1. Alcohols
Isomerism & Physical Properties
D.M S.J K.M

2. Contents
Introduction: Learning Objectives
What is Isomerism
Isomerism in Hydrocarbons & Classification
Alcohols Isomerism
Examples and Questions
2
Physical Properties

3. Introduction: Learning Objectives
What is Isomerism
2. Review İsomerism in Hydrocarbons;
3. Understand İsomerism in Alcohols;
4. Determine Physical Properties of
Alcohols;
1. Identify İsomers;
5. Explain why boiling points of alcohols
are higher than alkanes, ethers etc. ;
6. Discuss the factors that are affect to the
physical properties of alcohols ;

4. What is Isomerism ?
Similarities
Differences
Flashback: Isomerism in Hydrocarbons
Car Parts: Tire,
Windows, etc.
Different
Characteristics
Isomers are compounds with the same chemical formulas but
different structures and therefore, properties

5. I. Isomers
 Classification of isomers:
a. Constitutional isomers
i. Chain isomerism
ii. Position isomerism
iii. Functional group isomerism
II. Isomers of alcohols: Ethers
 Structures of ethers
Isomerism in Hydrocarbons & Classification

6. Butane 2-methylpropane
Chain Isomers
C4H10 C4H10
Isomerism in Hydrocarbons & Classification

7. Structural isomers are compounds that have the same molecular formula
and different connectivity.
Website
• https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modul
es_(Organic_Chemistry)/Fundamentals/Isomerism_in_Organic_Compounds/Structu
ral_Isomerism_in_Organic_Molecules
Structural (Constitutional) Isomers

8. Alcohols Isomerism

9. 9
Chain Isomerism
2-Methyl-1-propanol
1-butanol

10. More Examples: Chain isomers
C4H10O

11. 11
Position Isomerism
2-Propanol
1-Propanol

12. More Examples: Position
isomers
C5H12O

13. 13
Functional Isomerism
Dimethyl Ether
Ethanol
3

14. More Examples: Functional
isomers
C4H10O
C3H8O

15. II. Isomers of alcohols:
Ethers
R-O-R’ CnH2n+2O

16. Let’s practice:
Draw and classify structural isomers of C4H10O
(Homework)
Draw and classify structural isomers of C5H12O

17. Physical Properties: Intermolecular vs Intramolecular Forces

19. 1. Van der Waals forces:
• Dipole-dipole forces
• London dispersion forces
Intermolecular Forces:
2. Hydrogen bonds
Intramolecular Forces:
1. Covalent bonds:
i. Non-polar covalent
bonds
ii. Polar covalent bonds
2. Ionic bonds
3. Metallic bonds

20. C5H12O
Pentan-1-ol 2,2-dimethyl propan-1-ol
Isomers are compounds whose properties are different because their atoms
are bonded together in different arrangements.
Example:
Boiling point = 138 °C Boiling point = 113,5 °C
Physical Properties of Isomer Alcohols

21. A straight-chain alkane will have a boiling point higher than a branched-chain alkane due
to the greater surface area in contact, thus the greater van der Waals forces, between
adjacent molecules.

25. The boiling points of the alcohols increase as the number of carbon atoms increases.
Ether molecules have no hydrogen atom on the oxygen atom (that is, no OH group).
Therefore there is no intermolecular hydrogen bonding between ether molecules, and ethers
therefore have quite low boiling points for a given molar mass.

26. Solubility in water:
Alcohols Ethers

28. Classification

29. Condensed Structural
Formula
Name Molar Mass Boiling Point (°C)
Intermolecular Hydrogen
Bonding in Pure Liquid?
C2H6O
CH3OCH3 dimethyl ether 46 –25 no
CH3CH2OH ethyl alcohol 46 78 yes
C4H8O
CH3CH2OCH2CH3 diethyl ether 74 35 no
CH3CH2CH2CH2OH butyl alcohol 74 117 yes

31. Formula Name
Solubility in
Water (g/100 g)
CH3OH methanol infinitely soluble
CH3CH2OH ethanol infinitely soluble
CH3(CH2)2OH propanol infinitely soluble
CH3(CH2)3OH butanol 9
CH3(CH2)4OH pentanol 2.7
CH3(CH2)5OH hexanol 0.6
CH3(CH2)6OH heptanol 0.18
CH3(CH2)7OH octanol 0.054
CH3(CH2)9OH decanol insoluble in water
Solubilities of Alcohols in Water

32. Methanol vs Ethanol
1. Ethanol and methanol are liquids that sound the same and have
many of the same physical characteristics including look and smell.
2. Ethanol is safe to consume in moderate amounts and is found in all
alcoholic beverages whereas methanol should be avoided at all costs
as even a small dose can cause blindness or death.
3. Ethanol is used for alcohol, cleaning, solvents, and fuels, and while
methanol is also found in solvents and fuels, it is primarily used to
make other chemicals.

33. Difference between Ethanol and Methanol
Ethanol is a type of alcohol with its
carbon skeleton consisting of an ethyl
ring.
Methanol consists of in its carbon bond
methyl group.
Ethanol is a poor acid compared with
water, in terms of acidity.
Methanol has higher acidity than
liquids.
Ethanol has a heavy, burning smell and
emits bright blue flame.
Methanol is unpredictable and has a
characteristic odour. When burning it
gives off light white flame.
Ethanol is typically prepared by the
fermentation of food crops from
factories.
Methanol is manufactured mainly by
synthetic processes.
Ethanol is the primary ingredient of
alcoholic beverages.
Since methanol is highly poisonous it is
not appropriate for use at all. Generally
used in the manufacturing of products
such as formaldehyde etc.

34. Let’s practice:
1. Which one of the following compounds is an isomer of CH3CH2CH2CH2OH?
(a) CH3CH2CH2OH
(b) CH3CH(OH)CH3
(c) CH3CH2CH2OCH3
(d) CH3CH2CH2CH3
(e) none of the above

35. Let’s practice:
1. Which one of the following alcohols would have the lowest boiling point?
(a) butanol
(b) ethanol
(c) 2-methyl 2-butanol
(d) propanol

36. Let’s practice:
1. An alcohol has a higher boiling point than an alkane with the same
length carbon chain. True or false?
a) True
b) False

37. 1. Draw and classify structural isomers of C6H14O
2. Using Alcohol Worksheet (jpeg) identify chain
and position isomers