0 0 Moodle
Home Revision Notes Courses For Schools Blog My Account Cart
Moodle
Cambridge International AS & A Level Chemistry – Organic Chemistry

Topic 15
Halogen Compounds

Topic 15 covers the production of halogenoalkanes by free-radical substitution, electrophilic addition and substitution of alcohols, their classification, nucleophilic substitution with NaOH(aq), KCN, NH₃ and aqueous silver nitrate, elimination with ethanolic NaOH, the Sₙ1 and Sₙ2 mechanisms with the inductive effects of alkyl groups, and the different reactivities of halogenoalkanes explained by C–X bond strengths.

Exam Papers
Papers 1 & 2
9701 AS Level
Learning Outcomes
15.1.1 – 15.1.7
7 sections covered
Topic Parts
5 pages
Revision notes available
Exam Board
Cambridge
9701 (2025 onwards)

Revision Notes

Work through Topic 15 Halogen Compounds in a structured sequence.

Seven types
Reaction Types
and Mechanisms
1
Available

Reaction Types, Mechanisms and Nucleophiles

Organic reaction types and mechanisms: addition, elimination, substitution, oxidation, reduction, hydrolysis, polymerisation, curly arrows, heterolytic fission, electrophiles, nucleophiles and bond polarity.

Start revising
C–X bond
Halogenoalkanes
and Bonding
2
Available

Halogenoalkanes: Naming, Classification and the C–X Bond

Halogenoalkanes: nomenclature and formulae, primary, secondary and tertiary, the polar carbon–halogen bond, bond enthalpies and uses.

Start revising
Lone pair attacks δ+
Nucleophilic
Substitution
3
Available

Nucleophilic Substitution Reactions

Nucleophilic substitution of halogenoalkanes: hydroxide, water, ammonia and cyanide as nucleophiles, conditions, products and the curly-arrow mechanism.

Start revising
OH⁻ as a base
Elimination
Reactions
4
Available

Elimination Reactions of Halogenoalkanes

Elimination of halogenoalkanes: ethanolic KOH, hydroxide as a base, alkene products and isomers, substitution versus elimination.

Start revising
AgNO₃ in ethanol
Rates of
Hydrolysis
5
Available

Rates of Hydrolysis and Bond Enthalpy

Rates of hydrolysis of halogenoalkanes: the silver nitrate experiment, precipitate colours, bond enthalpy trend for C–Cl, C–Br and C–I, and primary, secondary and tertiary comparison.

Start revising
Specification Coverage

Topic 15 Halogen Compounds – Cambridge International AS Level Chemistry

The following Cambridge learning outcomes state what candidates should be able to do. Wording is taken from the Cambridge International AS & A Level Chemistry (9701) syllabus.

15.1 Halogenoalkanes

15.1.1(a)-i
recall the reaction (reagents and conditions) by which halogenoalkanes can be produced: the free-radical substitution of alkanes by Cl₂ in the presence of ultraviolet light, as exemplified by the reactions of ethane
15.1.1(a)-ii
recall the reaction (reagents and conditions) by which halogenoalkanes can be produced: the free-radical substitution of alkanes by Br₂ in the presence of ultraviolet light, as exemplified by the reactions of ethane
15.1.1(b)-i
recall the reaction (reagents and conditions) by which halogenoalkanes can be produced: electrophilic addition of an alkene with a halogen, X₂, at room temperature
15.1.1(b)-ii
recall the reaction (reagents and conditions) by which halogenoalkanes can be produced: electrophilic addition of an alkene with a hydrogen halide, HX(g), at room temperature
15.1.1(c)-i
recall the reaction (reagents and conditions) by which halogenoalkanes can be produced: substitution of an alcohol by reaction with HX(g)
15.1.1(c)-ii
recall the reaction (reagents and conditions) by which halogenoalkanes can be produced: substitution of an alcohol with KCl and concentrated H₂SO₄ or concentrated H₃PO₄
15.1.1(c)-iii
recall the reaction (reagents and conditions) by which halogenoalkanes can be produced: substitution of an alcohol with PCl₃ and heat
15.1.1(c)-iv
recall the reaction (reagents and conditions) by which halogenoalkanes can be produced: substitution of an alcohol with PCl₅
15.1.1(c)-v
recall the reaction (reagents and conditions) by which halogenoalkanes can be produced: substitution of an alcohol with SOCl₂
15.1.2
classify halogenoalkanes into primary, secondary and tertiary
15.1.3(a)
describe the nucleophilic substitution reaction of halogenoalkanes with NaOH(aq) and heat to produce an alcohol
15.1.3(b)
describe the nucleophilic substitution reaction of halogenoalkanes with KCN in ethanol and heat to produce a nitrile
15.1.3(c)
describe the nucleophilic substitution reaction of halogenoalkanes with NH₃ in ethanol heated under pressure to produce an amine
15.1.3(d)
describe the nucleophilic substitution reaction of halogenoalkanes with aqueous silver nitrate in ethanol as a method of identifying the halogen present as exemplified by bromoethane
15.1.4
describe the elimination reaction with NaOH in ethanol and heat to produce an alkene as exemplified by bromoethane
15.1.5-a
describe the SN₁ mechanism of nucleophilic substitution in halogenoalkanes including the inductive effects of alkyl groups
15.1.5-b
describe the SN₂ mechanism of nucleophilic substitution in halogenoalkanes including the inductive effects of alkyl groups
15.1.6-a
recall that primary halogenoalkanes tend to react via the SN₂ mechanism
15.1.6-b
recall that tertiary halogenoalkanes tend to react via the SN₁ mechanism
15.1.6-c
recall that secondary halogenoalkanes tend to react by a mixture of the SN₁ and SN₂ mechanisms, depending on structure
15.1.7-a
describe the different reactivities of halogenoalkanes (with particular reference to the relative strengths of the C–X bonds as exemplified by the reactions of halogenoalkanes with aqueous silver nitrate)
15.1.7-b
explain the different reactivities of halogenoalkanes (with particular reference to the relative strengths of the C–X bonds as exemplified by the reactions of halogenoalkanes with aqueous silver nitrate)