Topic 16 Haloalkanes

16 Haloalkanes

16.1 Can understand and describe the haloalkanes

Candidates should be able to:

(a) write the general formula for haloalkanes;

(b) name haloalkanes according to the IUPAC nomenclature;

(c) describe the structural and optical isomerism in haloalkanes;

(d) state the physical properties of haloalkanes;

(e) describe the substitution reactions of haloalkanes as exemplified by the following reactions of bromoethane: hydrolysis, the formation of nitriles and the formation of primary amines;

(f) describe the elimination reactions of haloalkanes;

(g) describe the mechanism of nucleophilic substitution in haloalkanes (SN1 and SN2);

(h) explain the relative reactivity of primary, secondary and tertiary haloalkanes;

(i) compare the reactivity of chlorobenzene and chloroalkanes in hydrolysis reactions;

(j) explain the use of haloalkanes in the synthesis of organomagnesium compounds (Grignard reagents), and their use in reactions with carbonyl compounds;

(k) describe the uses of fluoroalkanes and chlorofluoroalkanes as inert substances for aerosol propellants, coolants and fire-extinguishers;

(l) state the use of chloroalkanes as insecticide such as DDT;

(m) describe the effect of chlorofluoroalkanes in the depletion of the ozone layer, and explain its mechanism.

16 Haloalkanes

16.1 Can understand and describe the haloalkanes

 

Candidates should be able to:

(a) write the general formula for haloalkanes;

 

 

(b) name haloalkanes according to the IUPAC nomenclature;

 

(c) describe the structural and optical isomerism in haloalkanes;

 

structural

optical isomerism

 

(d) state the physical properties of haloalkanes;

physical properties

 

 

(e) describe the substitution reactions of haloalkanes as exemplified by the following reactions of bromoethane: hydrolysis, the formation of nitriles and the formation of primary amines;

substitution reactions: reactions of bromoethane:

hydrolysis

 

formation of nitriles

formation of primary amines;

 

 

(f) describe the elimination reactions of haloalkanes;

elimination reactions

 

 

 

 

 

 

 

 

 

 

 

(g) describe the mechanism of nucleophilic substitution in haloalkanes (SN1 and SN2);

SN1 and SN2

(h) explain the relative reactivity of primary, secondary and tertiary haloalkanes;

relative reactivity of primary, secondary and tertiary

 

 

 

 

 

(i) compare the reactivity of chlorobenzene and chloroalkanes in hydrolysis reactions;

reactivity of chlorobenzene and chloroalkanes in hydrolysis

 

 

 

 

(j) explain the use of haloalkanes in the synthesis of organomagnesium compounds (Grignard reagents), and their use in reactions with carbonyl compounds;

synthesis of organomagnesium compounds (Grignard reagents)

use in reactions with carbonyl compounds

 

 

 

This then couples with the alkyl radical formed. q Diethyl ether is an especially good solvent for the formation of Grignard reagents because ethers are non-acidic (aprotic). Water or alcohols would protonate and thus destroy the Grignard reagent, because the Grignard carbon is highly nucleophilic.

(k) describe the uses of fluoroalkanes and chlorofluoroalkanes as inert substances for aerosol propellants, coolants and fire-extinguishers;

uses of fluoroalkanes and chlorofluoroalkanes as

 

inert substances for

 

aerosol propellants,

 

coolants and

 

fire-extinguishers;

 

 

(l) state the use of chloroalkanes as insecticide such as DDT;

 

(m) describe the effect of chlorofluoroalkanes in the depletion of the ozone layer, and explain its mechanism.

 

 

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