Chem Chapter 14 Final - IUPAC Naming, Reactions, and Physical Properties of Alcohols

How do you name alcohols according to IUPAC?

Identify the longest carbon chain containing the –OH group

Number the chain so that the carbon with the hydroxyl group gets the lowest possible number

Replace the “-e” in the parent alkane name with “-ol” to indicate the presence of the hydroxyl group

How do you name alcohols with multiple -OH groups?

Alcohols with multiple hydroxyl groups are named by adding diol, triol, etc., to indicate the number of -OH groups.

Examples:

• 1,2-propanediol (propylene glycol) has two hydroxyl groups.

• 1,2,3-propanetriol (glycerol) has three hydroxyl groups.

What is the general reaction for alcohol dehydration?

Process of removing water

Two ways dehydration of alcohols works

Intramolecular Dehydration (180°C)

Intermolecular Dehydration (140°C)

Intermolecular Dehydration (140°C)

Two alcohol molecules react to form an ether and water.
Example:
Ethanol + Ethanol → Diethyl Ether (C₂H₅OC₂H₅) + H₂O.

Intramolecular Dehydration (180°C)

Removes water from the same molecule, forming an alkene (double bond).
Example:
Ethanol (C₂H₅OH) → Ethene (C₂H₄) + H₂O

What are the oxidation reactions of alcohols?

Oxidation of Alcohols involves removing hydrogen atoms

Primary

Secondary

Tertiary

Primary Alcohols

Oxidize to aldehydes, and can be further oxidized to carboxylic acids.
Example:
Ethanol → Acetaldehyde → Acetic Acid

Secondary Alcohols

Secondary Alcohols: Oxidize to ketones.
Example:
Isopropanol → Acetone

Tertiary Alcohols

Do not undergo oxidation because no hydrogen atoms are attached to the carbon bearing the -OH group

What is the combustion reaction of alcohols?

Alcohols undergo combustion reactions, burning in the presence of oxygen to produce carbon dioxide (CO₂) and water (H₂O).

Example:
Ethanol (C₂H₅OH) + O₂ → CO₂ + H₂O

What are the physical properties of alcohols?

Solubility

Short-chain alcohols (e.g., methanol, ethanol) are soluble in water due to hydrogen bonding.

Long-chain alcohols (e.g., hexanol) have low solubility due to the nonpolar carbon chain.

What are the physical properties of alcohols?

Boiling Point

Alcohols have higher boiling points than alkanes due to hydrogen bonding between alcohol molecules.

• Methanol has a low boiling point.

• Ethanol has a higher boiling point than methanol.

• Hexanol has an even higher boiling point because it’s larger

What are the physical properties of alcohols?

Polarity

Alcohols are polar due to the hydroxyl group (-OH), which can form hydrogen bonds

How do alcohols react with halogens (Lucas Test)?

Tests the reactivity of alcohols with halogenating reagents (e.g., PCl₃, PBr₃)

Tertiary Alcohols with halogens (Lucas Test)

React the fastes

Secondary Alcohols with halogens (Lucas Test)

React with heat

Primary Alcohols with halogens (Lucas Test)

React very slowly

What are the chemical reactions of alcohols?

Oxidation

Dehydration

Esterification

Primary alcohol oxidation

Primary alcohols to aldehydes or acids

Secondary alcohol oxidation

Secondary alcohols to ketones

Tertiary alcohol oxidation

Tertiary alcohols do not oxidize

Dehydration

Alcohols lose water to form alkenes (180°C) or ethers (140°C)

Esterification

Alcohols react with acids to form esters and water

How does the boiling point of alcohols change with size?

Increases with the size of the molecule due to stronger London forces (more electrons and larger surface area)

Example of Boiling Point Size Changes in Alcohol

Methanol

(small molecule) has a low boiling point.

Example of Boiling Point Size Changes in Alcohol

Ethanol

(medium-sized) has a higher boiling point than methanol

Example of Boiling Point Size Changes in Alcohol

Hexanol

(larger molecule) has the highest boiling point due to increased molecular size and more intermolecular forces

What factors affect the solubility of alcohols in water?

The size of the alcohol molecule (shorter chains are more soluble).

The presence of the hydroxyl group (-OH), which forms hydrogen bonds with water molecules.

Longer alcohols (e.g., hexanol) are less soluble because their nonpolar carbon chains hinder hydrogen bonding with water.

Why are alcohols polar?

Alcohols are polar due to the hydroxyl group (-OH)

What does alcohol’s polarity allow them to do?

Form hydrogen bonds with other alcohol molecules and water, leading to higher boiling points and good solubility in water for smaller alcohols.

Become less soluble in water as the hydrocarbon chain length increases because the nonpolar tail becomes more dominant.

Primary Alcohol Structure

The –OH group is attached to a carbon that is bonded to two hydrogens (e.g., ethanol)

Secondary Alcohol Structure

The –OH group is attached to a carbon that is bonded to one hydrogen and one other carbon (e.g., isopropanol)

Tertiary Alcohol Structure

The –OH group is attached to a carbon that is bonded to three other carbons (e.g., tert-butyl alcohol)