3.3. Haloalkanes

Question 1

State the reagents and conditions needed to make a haloalkane from an alkane

Answer 1

Reagent: Cl₂, Br₂
Condition: UV light

Question 2

Why is UV light the essential condition required to make a haloalkane from an alkane

Answer 2

Breaks the halogen-halogen bond to form a radical and start the reaction

Question 3

State the mechanism needed to make a haloalkane from an alkane

Answer 3

Radical Substitution

Question 4

When making a haloalkane from an alkane how would you reduce the amount of further subsitution occuring

Answer 4

add excess alkane

Question 5

State the definition of a free radical

Answer 5

A species with an unpaired electron

Question 6

State the reagents and conditions needed to make a haloalkane from an alkene

Answer 6

Reagent: HCl, HBr
Condition: Room temperature and shake

Question 7

State the mechanism needed to make a haloalkane from an alkene

Answer 7

Electrophilic Addition

Question 8

State the reagents and conditions needed to make an alkene from a haloalkane

Answer 8

Reagent: NaOH/KOH
Condition: Ethanolic (reflux)

Question 9

State the mechanism needed to make an alkene from a haloalkane

Answer 9

Elimination

Question 10

State the reagents and conditions needed to make an alcohol from a alkene in a single step

Answer 10

Reagent: Steam
Condition: Concentrated phosphoric acid

Question 11

State the mechanism needed to make an alkyl hydrogen sulfate from a alkene

Answer 11

Electrophilic Addition

Question 12

State the reagents and conditions needed to make a nitrile from a haloalkane

Answer 12

Reagent: KCN
Condition: Aqueous and ethanolic

Question 13

State the mechanism needed to make a nitrile from a haloalkane

Answer 13

Nucleophilic Substitution

Question 14

State the reagents and conditions needed to make an alcohol from a haloalkane

Answer 14

Reagent: NaOH/KOH
Condition: Aqueous (heat under reflux)

Question 15

State the mechanism needed to make an alcohol from a haloalkane

Answer 15

Nucleophilic Substitution

Question 16

State the reagents and conditions needed to make a primary amine from a haloalkane in one step

Answer 16

Reagent: NH3
Condition: Excess
(ethanol, heat and pressure)

Question 17

State the mechanism needed to make a primary amine from a haloalkane in one step

Answer 17

Nucleophilic Substitution

Question 18

State the type of reaction needed to make a primary amine from a nitrile

Answer 18

Reduction

Question 19

State the reagents and conditions needed to make a primary amine from a haloalkane in two steps

Answer 19

**First **
Reagent: KCN
Condition: Aqueous and Ethanolic
Second
Reagent: Hydrogen
Condition: Nickel Catalyst

Question 20

Explain why a haloalkane such as chloromethane is attacked by a nucleophile in a nucleophilic substitution reaction

Answer 20

Chlorine is more electronegative than carbon. Carbon is partially positive. Lone pair on nucleophile is attracted to the carbon

Question 21

Define a nucleophile

Answer 21

electron pair donor

Question 22

Define an electrophile

Answer 22

electron pair acceptor

Question 23

Why does 1-iodobutane have a faster rate of hydrolysis than 1-chlorobutane?

Answer 23

C-I bond is weaker than C-Cl bond (less energy is required to break the bond)

Question 24

Write an equation for the reaction of ethane with chlorine to form chloroethane and a by-product

Answer 24

CH3CH3 + Cl2 –> CH2ClCH3 + HCl

Question 25

Write an equation for the reaction of propane with bromine to form 2-bromopropane and a by-product

Answer 25

CH3CH2CH3 + Br2 --> CH3CHBrCH3 + HBr

Question 26

Write the propagation steps involved in the formation of chloroethane from chlorine and ethane

Answer 26

CH3CH3 + *Cl --> *CH2CH3 + HCl *CH2CH3 + Cl2 --> CH2ClCH3 + *Cl

Question 27

Write the propagation steps involved in the formation of 2-bomoprpane from bromine and propane

Answer 27

CH3CH2CH3 + *Br --> CH3*CHCH3 + HBr CH3*CHCH3 + Br2 --> CH3CHBrCH3 + *Br

Question 28

Write the propagation steps involved in the formation of 1-chlorobutane from chlorine and butane

Answer 28

CH3CH2CH2CH3 + *Cl --> *CH2CH2CH2CH3 + HCl *CH2CH2CH2CH3 + Cl2 --> CH2ClCH2CH2CH3 + *Cl

Question 29

Desribe what happens in the termination stage of free-radical substitution

Answer 29

two radicals combine

Question 30

Outline the mechanism for the formation of butan-1-ol from 1-bromo butane

Answer 30

Question 31

Outline the mechanism for the formation of but-1-ene from 2-bromobutane

Answer 31

Question 32

Define Structural Isomers

Answer 32

Molecules with the same molecular formula but different structural formulae

Question 33

Define steroisomerism

Answer 33

Molecules with the same molecular and structural formulae but different arrangement of atoms in space