Alcohols and Ethers | B.Sc. 1st Year Chemistry

1. Introduction to Alcohols and Ethers

Alcohols

Alcohols are organic compounds containing a hydroxyl group (-OH) attached to a saturated carbon atom.

General representation: R-OH

The carbon bearing the hydroxyl group is generally sp3 hybridized in ordinary alcohols.

Ethers

Ethers are organic compounds in which an oxygen atom is bonded to two carbon-containing groups.

General representation: R-O-R'

Examples

CH3OH Methanol C2H5OH Ethanol CH3CH2CH2OH Propan-1-ol CH3-O-CH3 Dimethyl ether CH3-O-C2H5 Methoxyethane

Remember: Alcohol = R-OH. Ether = R-O-R'.

2. Classification of Alcohols

2.1 Monohydric alcohols

Alcohols containing one hydroxyl group are called monohydric alcohols.

CH3OH C2H5OH

2.2 Dihydric alcohols

Alcohols containing two hydroxyl groups are called dihydric alcohols.

HO-CH2-CH2-OH Ethane-1,2-diol

2.3 Trihydric alcohols

Alcohols containing three hydroxyl groups are called trihydric alcohols.

HOCH2-CHOH-CH2OH Propane-1,2,3-triol

Classification according to the carbon bearing -OH

Primary alcohol

In a primary alcohol, the carbon attached to the -OH group is attached to only one other carbon atom.

R-CH2-OH

Secondary alcohol

R-CH(OH)-R'

Tertiary alcohol

OH | R---C---R' | R''

Easy method: Look at the carbon directly attached to OH. Count how many carbon groups are attached to that carbon.

3. Nomenclature of Alcohols

Select the longest carbon chain containing the hydroxyl group.
Number the chain from the end nearest the -OH group.
Replace the ending -e of the parent alkane by -ol.
Give the position of the hydroxyl group.

Examples

CH3OH Methanol

CH3CH2OH Ethanol

CH3CH2CH2OH Propan-1-ol

CH3CH(OH)CH3 Propan-2-ol

CH3CH2CH(OH)CH3 Butan-2-ol

Remember: In alcohol nomenclature, the -OH group gets priority when numbering the carbon chain.

4. Structure and Bonding

In ordinary alcohols, the carbon atom attached to oxygen is generally sp3 hybridized. Oxygen also uses sp3-like hybrid orbitals and possesses two lone pairs.

H | R - C - O - H | H Oxygen has two lone pairs.

Polarity of O-H bond

Oxygen is more electronegative than hydrogen. Therefore, the O-H bond is polar.

R-Oδ−-Hδ+

This polarity helps explain many reactions of alcohols, especially their reactions with sodium and hydrogen halides.

Hydrogen bonding

Alcohol molecules can form hydrogen bonds because the hydrogen attached to oxygen is partially positive and oxygen contains lone pairs.

Exam point: Hydrogen bonding explains the relatively high boiling points of lower alcohols compared with hydrocarbons of similar molecular mass.

5. Physical Properties of Alcohols

Boiling point

Alcohols generally have higher boiling points than hydrocarbons of comparable molecular mass because alcohol molecules form hydrogen bonds.

Solubility in water

Lower alcohols are appreciably soluble in water because their hydroxyl group can form hydrogen bonds with water.

As the hydrocarbon chain becomes longer, the non-polar part becomes more important and water solubility decreases.

Effect of branching

Branching can reduce surface area and generally lowers boiling point.

Ethers

Ethers cannot hydrogen-bond with themselves as strongly as alcohols because they do not contain an O-H bond. However, ether oxygen can accept hydrogen bonds from water and alcohol molecules.

Remember: Alcohols have O-H bonds and can form strong intermolecular hydrogen bonding. Ethers have oxygen but no O-H bond.

6. Preparation of Alcohols

Important methods include hydration of alkenes, hydrolysis of alkyl halides, reduction of carbonyl compounds, Grignard reactions and fermentation for ethanol.

Important preparation methods

Hydrolysis of alkyl halides
Hydration of alkenes
Reduction of aldehydes
Reduction of ketones
Grignard reaction
Fermentation of sugars

7. Preparation by Hydration of Alkenes

Alkenes react with water in the presence of an acid catalyst to form alcohols.

Example: hydration of ethene

Overall reaction

CH2=CH2 + H2O --H+--> CH3CH2OH

Step 1: Protonation of alkene

CH2=CH2 + H+ -> CH3-CH2+

Step 2: Water attacks the carbocation

CH3-CH2+ + H2O -> CH3-CH2-OH2+

Step 3: Deprotonation

CH3-CH2-OH2+ -> CH3-CH2-OH + H+

The acid catalyst is regenerated at the end of the mechanism.

Propene hydration

CH3-CH=CH2 + H2O --H+--> CH3-CH(OH)-CH3

Under ordinary acid-catalyzed hydration, the reaction follows Markovnikov orientation because the more stable carbocation intermediate is favored.

Memory tip: In acid-catalyzed hydration, think: protonate → carbocation → water attack → remove H+.

8. Preparation by Grignard Reaction

Grignard reagents have the general formula RMgX and react with carbonyl compounds. After hydrolysis, alcohols are obtained.

RMgX Grignard reagent

The reaction must normally be protected from moisture because water destroys the Grignard reagent.

Reaction with formaldehyde

RMgX + HCHO -> R-CH2-OMgX

Step 1: The carbon of the Grignard reagent behaves as a nucleophilic carbon.

R-MgX -> R− + MgX+

Step 2: The carbon attacks the carbonyl carbon.

R− + H-C(=O)-H -> R-CH(O−)-H

Step 3: The alkoxide reacts with water during acidic work-up.

R-CH(O−)-H + H+ -> R-CH(OH)-H

R-CH(OH)-H = R-CH2OH

Reaction of a Grignard reagent with formaldehyde therefore gives a primary alcohol after hydrolysis.

Reaction with aldehydes

RMgX + R'CHO -> R'CH(OMgX)R

R'CH(OMgX)R + H2O -> R'CH(OH)R + Mg(OH)X

This generally gives a secondary alcohol, except when the aldehyde is formaldehyde.

Reaction with ketones

RMgX + R'COR'' -> R'C(OMgX)(R)(R'')

R'C(OMgX)(R)(R'') + H2O -> R'C(OH)(R)(R'')

Reaction with a ketone gives a tertiary alcohol after hydrolysis.

Common mistake: Never ignore the water-sensitive nature of Grignard reagents. Water reacts with RMgX before it can attack the intended carbonyl compound.

9. Preparation by Reduction of Carbonyl Compounds

Aldehyde → Primary alcohol

R-CHO + 2[H] -> R-CH2OH

Step 1: The carbonyl group is reduced.

R-C(=O)-H -> R-CH(OH)-H

Step 2: The final product is a primary alcohol.

R-CHO -> R-CH2OH

Ketone → Secondary alcohol

R-CO-R' + 2[H] -> R-CH(OH)-R'

CH3COCH3 + 2[H] -> CH3CH(OH)CH3

Common reducing agents include sodium borohydride and lithium aluminium hydride, depending on the reaction conditions and syllabus.

Remember: Aldehyde reduction → primary alcohol. Ketone reduction → secondary alcohol.

10. Preparation of Ethanol by Fermentation

Ethanol can be prepared by fermentation of sugars using microorganisms such as yeast under suitable conditions.

Overall reaction

C6H12O6 --yeast--> 2C2H5OH + 2CO2

Step 1: Glucose is metabolized by yeast.

C6H12O6 -> intermediate products

Step 2: The metabolic pathway ultimately produces ethanol and carbon dioxide under fermentation conditions.

C6H12O6 -> 2C2H5OH + 2CO2

Fermentation is carried out under controlled conditions where yeast converts fermentable sugars into ethanol and carbon dioxide.

Exam point: Remember the balanced overall equation rather than trying to write every biochemical intermediate in a basic organic chemistry answer.

11. Reaction of Alcohols with Sodium

Alcohols react with active metals such as sodium to form sodium alkoxides and hydrogen gas.

Overall reaction

2ROH + 2Na -> 2RONa + H2

2C2H5OH + 2Na -> 2C2H5ONa + H2

Mechanism

Step 1: Sodium reacts with the acidic hydrogen of the O-H bond.

RO-H + Na -> RO⁻Na+ + H•

Step 2: Two hydrogen atoms combine.

H• + H• -> H2

2ROH + 2Na -> 2RONa + H2

The reaction demonstrates the weak acidic character of alcohols.

Important: Alcohols are much weaker acids than carboxylic acids. The reaction with sodium does not mean that alcohols are strongly acidic.

12. Reaction of Alcohols with Hydrogen Halides

Alcohols react with hydrogen halides to form alkyl halides.

ROH + HX -> RX + H2O

Example: ethanol with HBr

CH3CH2OH + HBr -> CH3CH2Br + H2O

Step 1: Protonation of alcohol

CH3CH2OH + H+ -> CH3CH2OH2+

Step 2: Bromide ion attacks the carbon

CH3CH2OH2+ + Br− -> CH3CH2Br + H2O

Primary alcohol

Primary alcohols commonly react through an SN2 pathway.

ROH + H+ -> ROH2+

X− + R-CH2-OH2+ -> R-CH2-X + H2O

Tertiary alcohol

Tertiary alcohols can form relatively stable carbocations after protonation and loss of water, so an SN1 pathway is common.

R3COH + H+ -> R3COH2+

R3COH2+ -> R3C+ + H2O

R3C+ + X− -> R3CX

Remember: Primary alcohol → usually SN2. Tertiary alcohol → often SN1.

13. Reaction with PCl5 and PCl3

Using PCl5

ROH + PCl5 -> RCl + POCl3 + HCl

Step 1: The oxygen of the alcohol attacks the phosphorus center of PCl5.

ROH + PCl5 -> ROH-PCl5 intermediate

Step 2: Chloride becomes available as a nucleophile.

ROH-PCl5 -> R-O-PCl4 + HCl

Step 3: Chloride replaces the oxygen-containing group at carbon.

R-O-PCl4 + Cl− -> RCl + POCl3

Using PCl3

3ROH + PCl3 -> 3RCl + H3PO3

Memory tip: Alcohol + phosphorus chlorides → alkyl chloride.

14. Reaction with Thionyl Chloride

Thionyl chloride, SOCl2, is an important reagent for converting alcohols into alkyl chlorides.

ROH + SOCl2 -> RCl + SO2 + HCl

Step 1: The alcohol oxygen attacks sulfur of thionyl chloride.

ROH + SOCl2 -> RO-S(O)Cl + HCl

Step 2: An activated alkyl chlorosulfite intermediate is formed.

ROH -> RO-S(O)Cl

Step 3: Chloride attacks the carbon and the leaving group decomposes.

RO-S(O)Cl + Cl− -> RCl + SO2 + Cl−

Overall: ROH + SOCl2 -> RCl + SO2 + HCl

Why SOCl2 is useful: The inorganic products SO2 and HCl are gases, so the reaction can give a relatively clean alkyl chloride product.

15. Dehydration of Alcohols

Alcohols can lose water on heating in the presence of a suitable acid to form alkenes.

Example: ethanol

CH3CH2OH --conc. H2SO4, heat--> CH2=CH2 + H2O

Step 1: Protonation of alcohol

CH3CH2OH + H+ -> CH3CH2OH2+

Step 2: Water leaves

CH3CH2OH2+ -> CH3CH2+ + H2O

Step 3: Removal of a beta hydrogen

CH3-CH2+ -> CH2=CH2 + H+

The acid catalyst is regenerated.

For secondary and tertiary alcohols

Secondary and tertiary alcohols commonly undergo acid-catalyzed dehydration through carbocation-type pathways under suitable conditions.

(CH3)3COH + H+ -> (CH3)3COH2+

(CH3)3COH2+ -> (CH3)3C+ + H2O

(CH3)3C+ -> (CH3)2C=CH2 + H+

Zaitsev orientation

When more than one alkene can form, the more substituted alkene is often the major product under typical acid-catalyzed elimination conditions.

Memory tip: Dehydration means removal of H2O from alcohol to form an alkene.

Common mistake: Do not confuse dehydration with oxidation. Dehydration removes H2O and commonly produces an alkene.

16. Oxidation of Alcohols

Oxidation behavior depends strongly on whether the alcohol is primary, secondary or tertiary.

Primary alcohol

R-CH2OH --[O]--> R-CHO

R-CHO --[O]--> R-COOH

Under controlled oxidation, a primary alcohol gives an aldehyde. Further oxidation gives a carboxylic acid.

Mechanism idea

Step 1: The carbon bearing OH loses hydrogen during oxidation.

R-CH2OH -> R-CHO

Step 2: Further oxidation converts the aldehyde into a carboxylic acid.

R-CHO + [O] -> R-COOH

Secondary alcohol

R-CH(OH)-R' --[O]--> R-CO-R' + H2O

Secondary alcohols are oxidized to ketones.

Tertiary alcohol

Tertiary alcohols do not normally undergo oxidation under mild conditions because the carbon bearing OH has no hydrogen that can be removed in the usual oxidation pathway.

Oxidation mechanism of a secondary alcohol

R2CHOH -> R2C=O + 2[H]

Step 1: The oxidizing agent interacts with the alcohol oxygen.

R2CHOH + [O] -> oxidized intermediate

Step 2: Hydrogen is removed from the carbon and oxygen-bearing group rearranges to the carbonyl.

R2CHOH -> R2C=O

Most important: Primary → aldehyde → acid. Secondary → ketone. Tertiary → resistant to mild oxidation.

17. Esterification of Alcohols

Alcohols react with carboxylic acids in the presence of an acid catalyst to form esters and water.

Example: ethanol + ethanoic acid

CH3COOH + C2H5OH --conc. H2SO4, heat--> CH3COOC2H5 + H2O

Step 1: Protonation of carbonyl oxygen

CH3-C(=O)-OH + H+ -> CH3-C(=OH+)-OH

Step 2: Alcohol attacks the carbonyl carbon

CH3-C(=OH+)-OH + C2H5OH -> tetrahedral intermediate

Step 3: Proton transfers occur

tetrahedral intermediate -> protonated ester intermediate

Step 4: Water leaves

protonated ester -> CH3COOC2H5H+ + H2O

Step 5: Deprotonation

CH3COOC2H5H+ -> CH3COOC2H5 + H+

The reaction is reversible, and the acid catalyst is regenerated.

Memory sequence: Protonate → attack → proton transfer → water leaves → deprotonate.

18. Ethers

Ethers contain an oxygen atom bonded to two carbon groups.

R-O-R'

Examples

CH3-O-CH3 Dimethyl ether C2H5-O-C2H5 Diethyl ether CH3-O-C2H5 Methoxyethane

Symmetrical ethers

Both groups attached to oxygen are identical.

C2H5-O-C2H5

Unsymmetrical ethers

The two groups are different.

CH3-O-C2H5

Remember: Ether has oxygen between two carbon groups: R-O-R'.

19. Nomenclature of Ethers

In the common system, the names of the two alkyl groups attached to oxygen are followed by the word "ether".

CH3-O-CH3 Dimethyl ether

CH3-O-C2H5 Methyl ethyl ether

In IUPAC nomenclature, ethers are commonly named as alkoxyalkanes.

CH3-O-CH2CH3 Methoxyethane

C2H5-O-CH2CH2CH3 1-ethoxypropane

Memory tip: Smaller group + O becomes the alkoxy substituent. The larger chain is normally chosen as the parent alkane.

20. Preparation of Ethers

Important methods include dehydration of alcohols and Williamson ether synthesis.

20.1 Dehydration of alcohols

At suitable temperature and acid conditions, two alcohol molecules can combine to form an ether and water.

Example: diethyl ether

2C2H5OH --conc. H2SO4, about 413 K--> C2H5-O-C2H5 + H2O

Step 1: Protonation

C2H5OH + H+ -> C2H5OH2+

Step 2: Nucleophilic attack by another alcohol

C2H5OH + C2H5OH2+ -> C2H5-O(+H)-C2H5 + H2O

Step 3: Deprotonation

C2H5-O(+H)-C2H5 -> C2H5-O-C2H5 + H+

The acid catalyst is regenerated.

Important condition: Temperature matters. Conditions favoring intermolecular dehydration can give ether, while stronger heating commonly favors alkene formation.

21. Williamson Ether Synthesis

Williamson synthesis is one of the most useful methods for preparing ethers. An alkoxide ion reacts with an alkyl halide, usually through an SN2 mechanism.

General reaction

RONa + R'X -> ROR' + NaX

Step 1: Formation of alkoxide

ROH + Na -> RONa + 1/2 H2

Step 2: Alkoxide acts as a nucleophile

RO− + R'-X -> [RO---R'---X]−

Step 3: SN2 displacement

RO− + R'-X -> R-O-R' + X−

Example

C2H5ONa + CH3Br -> C2H5-O-CH3 + NaBr

Step 1: Ethoxide ion is present as the nucleophile.

C2H5O−

Step 2: Ethoxide attacks the methyl carbon from the backside.

C2H5O− + CH3-Br -> C2H5O-CH3 + Br−

Step 3: The product is formed in one SN2 displacement.

C2H5O− + CH3Br -> C2H5OCH3 + Br−

Why primary alkyl halides are preferred

SN2 attack occurs most easily at an unhindered carbon. Therefore primary alkyl halides generally give better results.

Why tertiary alkyl halides are unsuitable

With tertiary alkyl halides, the strong basic character of the alkoxide can favor elimination instead of the desired SN2 substitution.

Memory tip: Williamson = alkoxide + primary alkyl halide → ether.

Common mistake: Do not choose a bulky tertiary alkyl halide as the SN2 partner in Williamson synthesis.

22. Cleavage of Ethers with HI and HBr

Ethers can be cleaved by strong hydrogen halides, especially HI and HBr, under suitable conditions.

Example: diethyl ether with HI

C2H5-O-C2H5 + HI -> C2H5I + C2H5OH

Step 1: Protonation of ether oxygen

C2H5-O-C2H5 + H+ -> C2H5-O(+H)-C2H5

Step 2: Iodide attacks an ethyl carbon

I− + C2H5-O(+H)-C2H5 -> C2H5I + C2H5OH

With excess HI and strong heating, the alcohol formed can react further.

C2H5OH + HI -> C2H5I + H2O

Overall with excess HI: C2H5-O-C2H5 + 2HI -> 2C2H5I + H2O

Unsymmetrical ethers

If the ether has a methyl or primary alkyl group, cleavage commonly occurs at the less hindered carbon through SN2 attack.

CH3-O-C2H5 + HI -> CH3I + C2H5OH

I− + CH3-O(+H)-C2H5 -> CH3I + C2H5OH

When a tertiary group is present

If one side is tertiary, cleavage can proceed through carbocation formation on the tertiary side under suitable conditions.

R-O-C(CH3)3 + H+ -> R-OH+ - C(CH3)3

R-OH+ - C(CH3)3 -> R-OH + (CH3)3C+

(CH3)3C+ + I− -> (CH3)3CI

Remember: Ether cleavage starts with protonation of oxygen. Then the halide ion breaks the C-O bond.

23. Anisole and Aryl Ethers

Anisole is methoxybenzene, in which a methoxy group is attached directly to a benzene ring.

C6H5-O-CH3 Anisole

Preparation of anisole

Anisole can be prepared using Williamson ether synthesis from sodium phenoxide and a suitable methyl halide.

C6H5ONa + CH3I -> C6H5OCH3 + NaI

Step 1: Phenoxide ion acts as the nucleophile.

C6H5O−

Step 2: Phenoxide attacks methyl iodide through SN2 displacement.

C6H5O− + CH3I -> C6H5OCH3 + I−

Important point

Aryl halides such as chlorobenzene generally do not undergo ordinary SN2 reactions at the aromatic carbon, so the alkyl-halide partner is usually chosen for Williamson synthesis.

Exam point: For anisole preparation, use phenoxide + methyl/primary alkyl halide rather than trying to force ordinary SN2 attack on an aryl halide.

24. Alcohols vs Ethers

Feature	Alcohol	Ether
Functional group	-OH	-O-
General formula	R-OH	R-O-R'
O-H bond	Present	Absent
Self hydrogen bonding	Strong	Much weaker
Boiling point	Generally higher	Generally lower
Important reaction	Oxidation, dehydration	Cleavage by HI/HBr
Preparation	Hydration, reduction, Grignard	Williamson synthesis

Primary vs Secondary vs Tertiary Alcohols

Type	General structure	Main oxidation product
Primary	R-CH2OH	Aldehyde, then acid
Secondary	R-CH(OH)-R'	Ketone
Tertiary	R3COH	Resistant to mild oxidation

25. Common Mistakes

Confusing an alcohol with an ether.
Forgetting that the -OH group determines the numbering in alcohol nomenclature.
Calling every alcohol a primary alcohol.
Forgetting the difference between primary, secondary and tertiary alcohols.
Writing alkene hydration without showing the carbocation mechanism when a mechanism is asked.
Forgetting that Grignard reagents are destroyed by water.
Confusing oxidation of primary and secondary alcohols.
Saying tertiary alcohols readily oxidize to ketones.
Confusing dehydration with oxidation.
Using a tertiary alkyl halide as the normal SN2 partner in Williamson synthesis.
Forgetting protonation of ether oxygen before ether cleavage.
Assuming ethers have an O-H bond.
Forgetting that SOCl2 converts alcohols into alkyl chlorides.

26. Worked Problems

Problem 1: Identify the type of alcohol

CH3-CH(OH)-CH3

The carbon attached to OH is attached to two other carbon groups.

Therefore, it is a secondary alcohol.

Problem 2: Oxidation of propan-1-ol

CH3CH2CH2OH --[O]--> CH3CH2CHO

CH3CH2CHO --[O]--> CH3CH2COOH

Propan-1-ol first gives propanal and on further oxidation gives propanoic acid.

Problem 3: Oxidation of propan-2-ol

CH3CH(OH)CH3 --[O]--> CH3COCH3

Product = propanone, a ketone.

Problem 4: Dehydration of ethanol

CH3CH2OH --conc. H2SO4, heat--> CH2=CH2 + H2O

The reaction is an elimination reaction.

Problem 5: Williamson synthesis

CH3ONa + C2H5Br -> CH3OC2H5 + NaBr

Sodium methoxide acts as the nucleophile and ethyl bromide undergoes SN2 substitution.

Problem 6: Ether cleavage

CH3-O-CH3 + HI -> CH3I + CH3OH

With excess HI and stronger heating:

CH3OH + HI -> CH3I + H2O

Overall: CH3-O-CH3 + 2HI -> 2CH3I + H2O

27. TU Examination Preparation

2-mark questions

Define alcohol.
Define ether.
What is a primary alcohol?
What is a secondary alcohol?
What is a tertiary alcohol?
Write the general formula of an ether.
What is Williamson ether synthesis?
What is esterification?
What happens when alcohol reacts with sodium?
What is dehydration of alcohol?

5-mark questions

Classify alcohols with suitable examples.
Explain the physical properties of alcohols.
Explain preparation of alcohols by hydration of alkenes.
Explain oxidation of primary, secondary and tertiary alcohols.
Explain Williamson ether synthesis.
Explain preparation and cleavage of ethers.
Explain esterification with mechanism.

10-mark questions

Discuss the preparation and chemical reactions of alcohols with mechanisms.
Explain the mechanism of acid-catalyzed dehydration of alcohols.
Discuss oxidation reactions of primary, secondary and tertiary alcohols.
Explain Williamson ether synthesis with detailed SN2 mechanism and limitations.
Describe preparation and chemical reactions of ethers.
Explain the cleavage of ethers by HI with suitable mechanisms.
Explain preparation of alcohols by Grignard reaction with suitable examples.

How to write a reaction mechanism answer

Write the overall reaction first.
Write the reagent and conditions.
Show the first bond-breaking or protonation step.
Show the intermediate.
Show nucleophilic attack or elimination as an equation.
Show the final product-forming step.
Mention why the particular mechanism occurs.
Add a short memory tip.

For a 10-mark answer: Equations should carry the mechanism. Use words to explain the equations rather than replacing the equations with long paragraphs.

28. Quick Revision

Alcohol functional group = -OH.
Ether functional group = -O-.
Alcohol general structure = R-OH.
Ether general structure = R-O-R'.
Primary alcohol = R-CH2OH.
Secondary alcohol = R-CH(OH)-R'.
Tertiary alcohol = R3COH.
Alcohols form strong intermolecular hydrogen bonds.
Lower alcohols are appreciably soluble in water.
Alkene hydration can give alcohols.
Grignard reagent + carbonyl compound → alcohol after hydrolysis.
Aldehyde reduction → primary alcohol.
Ketone reduction → secondary alcohol.
Alcohol + Na → sodium alkoxide + H2.
Alcohol + HX → alkyl halide + water.
Alcohol + SOCl2 → alkyl chloride + SO2 + HCl.
Dehydration of alcohol → alkene + water.
Primary alcohol → aldehyde → carboxylic acid.
Secondary alcohol → ketone.
Tertiary alcohol is resistant to mild oxidation.
Alcohol + carboxylic acid → ester + water.
Williamson synthesis uses an alkoxide and an alkyl halide.
Ether cleavage is commonly carried out using HI or HBr.

Most important equations

ROH + Na -> RONa + 1/2 H2

ROH + HX -> RX + H2O

ROH --H2SO4, heat--> alkene + H2O

RCH2OH --[O]--> RCHO --[O]--> RCOOH

R2CHOH --[O]--> R2C=O

ROH + R'COOH -> R'COOR + H2O

RONa + R'X -> ROR' + NaX

ROR' + HI -> RI + R'OH

29. Quick Check

1. What is the functional group of an alcohol?

The hydroxyl group, -OH.

2. What is the general structure of an ether?

R-O-R'.

3. What does oxidation of a primary alcohol first produce?

An aldehyde.

4. What does oxidation of a secondary alcohol produce?

A ketone.

5. What happens when ethanol reacts with sodium?

Sodium ethoxide and hydrogen are formed: 2C2H5OH + 2Na → 2C2H5ONa + H2.

6. What is the product of dehydration of ethanol?

Ethene: CH3CH2OH → CH2=CH2 + H2O.

7. Which reagent is commonly used in Williamson ether synthesis?

An alkoxide ion or sodium alkoxide reacts with an alkyl halide.

8. Why are primary alkyl halides preferred in Williamson synthesis?

They undergo SN2 attack more easily because the reaction center is less sterically hindered.

9. What reagent is commonly used to cleave ethers?

Strong hydrogen halides, especially HI or HBr.

10. What is the key first step in acid-catalyzed ether cleavage?

Protonation of the ether oxygen.

Final Revision Note

The most useful way to study alcohols and ethers is to connect their functional groups with their reactions. The O-H bond makes alcohols capable of hydrogen bonding and gives them reactions such as formation of alkoxides. The hydroxyl group can also be converted into a better leaving group before substitution or dehydration.

For alcohol reactions, remember these three major patterns:

Alcohol + [O] -> oxidation product

Alcohol --acid, heat--> alkene + H2O

Alcohol + HX -> alkyl halide + H2O

For ethers, the two reactions that should be especially clear are Williamson synthesis and cleavage by HI or HBr.

RO− + R'X -> R-O-R' + X−

R-O-R' + HI -> RI + R'OH

When a mechanism is asked in the examination, do not replace the reaction steps with a paragraph. Write the chemical equations for each important step and then use short explanations beside them.