Lesson 6: Introduction to Alcohols and Ether
Lesson Objections :
At the end of this lesson, you will be able to:
- define alcohols
- write the functional group of alcohols classify alcohols based on the number of hydroxyl groups
- write the general formulas of monohydric alcohols
- write the molecular formulas and the names of the first six members of the monohydric alcohols give the IUPAC names for the given alcohols
- classify monohydric alcohols based on the number of alkyl groups attached to the carbon atom carrying the hydroxyl group
- give some examples for primary, secondary and tertiary alcohols
- describe the physical properties of alcohols
- explain general methods of preparation of alcohols
- explain the industrial preparation of ethanol
- perform an experiment to prepare ethanol from sugar
- explain the chemical reactions of alcohols
Brainstorming question
- List some alcohols you know.
- Name the alcohol used in alcoholic beverages.
- What are the uses of alcohols in industry?Ethiopia uses an alcohol blended with gasoline to drive cars.
- What is the name of the alcohol?Hand sanitizers are used as an alternative to washing hands to kill most bacteria and viruses that spread colds and flu.
- Which alcohol (s) is present in hand sanitizers?
- Explain the effects of using carbon-based fuels on the increase in carbondioxide in the atmosphere and its consequences.
Key terms /Concepts
- Alcohols
- Ether
- Oxidation of alcohols
- Dehydration of alcohols
Alcohols are a class of organic compounds characterized by the presence of one or more hydroxyl groups (-OH) attached to a carbon atom. They are versatile compounds with various applications in industrial, medicinal, and everyday contexts. Here’s a summary of alcohols:
6.1 Introduction to Alcohol & Ether
In grade 10, we discussed the hydrocarbons and their reactions.
All other organic compounds can be considered to be derivatives of hydrocarbons. in these compounds, one or more hydrogen atoms of a hydrocarbon have been replaced by atom other than carbon to give functional group.


Many of the important functional groups in organic compounds contain oxygenated hydrocarbons.
Examples are alcohols ,ethers,aldehydes,ketones,carboxylic acids,and esters.
6.2 Alcohols and Ether
6.2.1 Classification of Alcohols
Alcohols may be classified as mono–, di–, tri- or poly hydric compounds depending on whether they contain one, two, three or many hydroxyl (–OH) groups respectively in their structures.
i. Monohydric alcohols are alcohols containing only one hydroxyl group. CH2-CH2-0H …………….Ethanol
ii) Dihydric alcohols are those containing two hydroxyl groups per molecule. They are also named glycols or diols.
Example ethane-1, 2- diol ……..CH2(OH)-CH2(0H)
iii) Trihydric alcohols are those containing three hydroxyl groups in their molecular structure .
Propane-1,2,3-triol…………CH2(OH)-CH2(0H)-CH2(OH)
Classification of monohydric alcohol
Monohydric alcohols may be further classified according to the carbon atom to which the hydroxyl group is attached.
Primary alcohols
In a primary alcohol, the carbon with the hydroxyl group is only attached to one alkylgroup
CH2-CH2-0H………..Ethanol
CH3-CH2-CH2-0H …………………1-Propanol
CH3-CH2-CH2 (CH3)CH2-0H…………2-Methyl -1- butanol
II Secondary alcohols
In a secondary alcohol, the carbon with the hydroxyl group is attached to two alkyl groups.

iii) a tertiary alcohol, the carbon with the hydroxyl group is attached to three other alkyl groups

iii) Tertiary alcohol
a tertiary alcohol, the carbon with the hydroxyl group is attached to three other alkyl group

6.2.2 Nomenclature of alcohols
The common name of an alcohol is derived from the common name of the alkyl group and adding the word alcohol to it. In the IUPAC system, an alcohol is named by replacing the e of the corresponding alkane name with alcohol
The common name of an alcohol is derived from the common name of the alkyl group and adding the word alcohol to it.In the IUPAC system, an alcoholis named by replacing the of the corresponding alkane name with ol. nomenclature of alcohols containing side chains or OH groups indifferent positions ,the longest chain to which the–Oh group is attached, is chosen asap aren’t structure.,starting from the end closer to the carbon atom to which the–Oh groupies bonded.The numberof –OH groups isindicated by adding the multiplicative prefix,di, tri,etc.,before„ol‟.

Physical properties of alcohol
The bond in-OH is polar because of the wide difference in electronegativity between oxygen and hydrogen.
Alcohols can form H-bonding with water molecules,thereby;l owner alcohols are soluble in water.Alcohols have higher melting and boiling points than hydrocarbons of comparable molecular size (mass).Because of hydrogen bonding in them.
Preparation of alcohols
The general laboratory methods of preparation of alcohols are:





Industrial Preparation of ethanol
Ethanol is manufactured industrially by:
- Fermentation of Carbohydrates such as Sugar


Most Liquor factories in Ethiopia use molasses.a by product of sugar industries,as a raw material to produce ethanol.in brewing industry,germinated barley called malt is used as the starting material.


Fermentation can produce an alcoholic beverage whose ethanol content is 12–15%only.Why?Because,The alcohol kills the yeast and inhibits it’s activity when the percentage is higher.
2.Catalytic Hydration of ethene:
Most ethanol is manufactured at present by this method.

Chemical properties of alcohols
Reactions of alcohols may involve the cleavage of the oxygen hydrogen bond(–O–H)or the carbon-oxygenbond(–C–O)
- 1. Reactions of alcohols involving cleavage of–O–H bond
A) Reaction With active metals
Alcohols react with like, Na,K,Mg, and other active metals liberate hydrogen and to form metal alkoxides.(products)
General reaction: 2R- CH2-OH + 2Na → 2R-CH2-ONa + H2
B. Oxidation of alcohol
depend on the type of alcohol and the nature of oxidizing agents,used in production of ther oxygen-containing organic compounds, such as aldehydes, ketones and carboxylic acids
I) Oxidation of primary alcohols
Depending on the oxidizing agent used, is oxidized to an aldehyde (mild oxidizing agents such as copper metal)

is aldehydes and then to carboxylic acids (such as acidified KMnO4 or K2Cr2O7 or CrO3 in H2SO4,)

ii) Oxidation of secondary alcohol
Yields ketone

iii) Tertiary alcohols and ketones are generally resistant to oxidation and they undertake No reaction under normal conditions.
However,they can undergo oxidation under drastic conditions to form a mixture of carboxylic acids.

2. Reactions involving cleavage of carbon–oxygen(C–O)bond in alcohols
Dehydration of alcohols:
is removal of a molecule of water from alcohol to form alkenes (treating with an acid such as H2SO4 or H3PO4and heat)
General reaction:



Secondary and tertiary alcohols dehydrate under milder conditions.
The over all tendency of alcohols to undergo dehydration is in the following order:

Ethers
Physical Properties of Ethers
- Ethers are polar oxygen containing organic compound (polarity of C-O bonds).
- Colorless,sweetsmelling,extremely volatile, and combustible liquids.
- The boiling points of ethers are much lower than those of alcohols of comparable molecular weight.
- Ethers not for minter molecular hydrogen bonding.
- Ether molecules are miscible in water.Because the oxygen atom of ether can also form hydrogen bonds with a water molecule.

Fig.hydrogen bonding between diethyl ether and water
Preparation of Ether
1. Dehydration of alcohols:
Dehydration ofalcohols produces alkenes and ethers under different conditions. in presence of protic acids(sulphuric acid,phosphoric acid)

2. Williamson ether synthesis:
In this method,analkyl halide is made to react with analkoxide which leads to the formation of ether.

Reaction of Ethers
- They resistance to chemical reaction.
- They donot react with oxidizing agents.
- Ethers are not affected by bases,however,they can react with proton donors to for moxonium salts.
3Li214Be225B2311Na281
Ethers are a class of organic compounds in which two alkyl or aryl groups are bonded to an oxygen atom. Ethers are widely used as solvents and have unique chemical and physical properties.
Oxidation of alcohols is a key reaction in organic chemistry, transforming alcohols into other functional groups such as aldehydes, ketones, or carboxylic acids. The product of alcohol oxidation depends on the type of alcohol (primary, secondary, or tertiary) and the conditions used.
Dehydration of alcohols is a chemical reaction in which water is removed from an alcohol molecule, resulting in the formation of an alkene. This reaction is a common method for synthesizing alkenes and typically occurs under acidic conditions.