Unit 14: Applications of Organic Chemistry
A: Understand the structures, reactions and properties of functional group
compounds.
Assignment title: Functional group chemistry for designer molecules
Functional groups determine the chemical reactivity of an organic molecule. A functional
group is a particular set of atoms in a molecule that are in charge of the chemical reactions
that are unique to that molecule. Organic compounds can be grouped into a number of major
categories according to the functional groups they contain. The placements of functional
groups inside the fundamental hydrocarbon framework are denoted by numbers in the
systematic names of organic
Name suffix or prefix structure example
halogenoalkane Fluoro-
Chloro-
Bromo-
Iodo-
alcohol -ol or hydroxy-
ketone -one
aldehyde -al
carboxylic -oic acid
, ester -oate
amine -amino or acid
P1: Explain the reactions of a range of carbonyl and non-carbonyl functional group
compounds.
Structures, reactions, uses and properties of non-carbonyl compounds: halogenoalkanes,
alcohols, amines
Halogenoalkanes
Halogenoalkanes are alkanes where one or more hydrogen atoms have been substituted for
a halogen atom, referred to as X. They are also known as haloalkanes or alkyl halides.
Halogenoalkanes are named using standard nomenclature rules.
- A prefix is added to the name of the alkane depending on what halogens are
attached.
- Another prefix is used to indicate how many atoms of each halogen are present.
- Numbers are used, where necessary, to indicate to which carbon atom(s) each
halogen is attached.
Example:
Halogenoalkanes are classified as primary, secondary, or tertiary.
- Primary halogenoalkanes are organic compounds that have a
carbon atom attached to one alkyl group and one halogen atom.
Therefore, the general structure of a primary halogenoalkanes is
R-CH 2 -X; R is an alkyl group while X is a halogen.
,Example:
Bromoethane 1-Chloropropane 1-iodo-2-methylpropane
- Secondary halogenoalkanes are organic compounds that have a
carbon atom attached to two alkyl groups and a halogen atom. The
general structure of a secondary halogenoalkanes is R 2 -C (-H)-X.
Here, the two alkyl groups (R group) can be similar or different
groups. We can denote these compounds as 2 0 haloalkanes.
Example:
Bromopropane Chloropropane
- Tertiary halogenoalkane, the carbon atom holding the halogen, is
attached directly to three alkyl groups, which may be any
combination of the same or different.
Examples:
2-bromo-2-methylpropane 2-chloro-2-methylpropane
Chemical properties
- Nucleophilic substitution
Halogenoalkanes are much more reactive than alkanes due to the presence of the
electronegative halogens. The halogen-carbon bond is polar causing the carbon to carry a
partial positive and the halogen a partial negative charge
A nucleophilic substitution reaction is one in which a nucleophile attacks a carbon atom
which carries a partial positive charge.
An atom that has a partial negative charge is replaced by the nucleophile
, Nucleophilic substitution of halogenoalkanes (OH−, NH3, primary amines), SN1 and
SN2 mechanisms of nucleophilic substitution, elimination reactions.
Nucleophilic substitution reactions:
1. Reaction with NaOH to form an alcohol
CH3CH2CL+ NaOH → CH3CH2OH + NaCl
Chloroethane + Sodium hydroxide → Ethanol + Sodium chloride
Mechanism: Nucleophilic
Reaction type: Substitution
Conditions: Aqueous + boil under reflux
2. Reaction with ammonia to form amines
Reaction type: Substitution
Mechanism: Nucleophilic
Conditions: NΗ3 in ethanol + heat
Reaction with potassium cyanide to form a nitrile (or cyanide).
CH3Cl + KCN → CH3CN + KCl
Chloromethane cyanide (nitrile)
Reaction type: Substitution
Mechanism: Nucleophilic
Conditions: KCN in water/ethanol + boil under reflux
Elimination Reactions
During an elimination reaction, a bond forms by the removal of two atoms or groups from
the original molecule. In most instances, the bond that forms is a π bond. Elimination
reactions compete with substitution reactions when alkyl halides react with a nucleophile
A: Understand the structures, reactions and properties of functional group
compounds.
Assignment title: Functional group chemistry for designer molecules
Functional groups determine the chemical reactivity of an organic molecule. A functional
group is a particular set of atoms in a molecule that are in charge of the chemical reactions
that are unique to that molecule. Organic compounds can be grouped into a number of major
categories according to the functional groups they contain. The placements of functional
groups inside the fundamental hydrocarbon framework are denoted by numbers in the
systematic names of organic
Name suffix or prefix structure example
halogenoalkane Fluoro-
Chloro-
Bromo-
Iodo-
alcohol -ol or hydroxy-
ketone -one
aldehyde -al
carboxylic -oic acid
, ester -oate
amine -amino or acid
P1: Explain the reactions of a range of carbonyl and non-carbonyl functional group
compounds.
Structures, reactions, uses and properties of non-carbonyl compounds: halogenoalkanes,
alcohols, amines
Halogenoalkanes
Halogenoalkanes are alkanes where one or more hydrogen atoms have been substituted for
a halogen atom, referred to as X. They are also known as haloalkanes or alkyl halides.
Halogenoalkanes are named using standard nomenclature rules.
- A prefix is added to the name of the alkane depending on what halogens are
attached.
- Another prefix is used to indicate how many atoms of each halogen are present.
- Numbers are used, where necessary, to indicate to which carbon atom(s) each
halogen is attached.
Example:
Halogenoalkanes are classified as primary, secondary, or tertiary.
- Primary halogenoalkanes are organic compounds that have a
carbon atom attached to one alkyl group and one halogen atom.
Therefore, the general structure of a primary halogenoalkanes is
R-CH 2 -X; R is an alkyl group while X is a halogen.
,Example:
Bromoethane 1-Chloropropane 1-iodo-2-methylpropane
- Secondary halogenoalkanes are organic compounds that have a
carbon atom attached to two alkyl groups and a halogen atom. The
general structure of a secondary halogenoalkanes is R 2 -C (-H)-X.
Here, the two alkyl groups (R group) can be similar or different
groups. We can denote these compounds as 2 0 haloalkanes.
Example:
Bromopropane Chloropropane
- Tertiary halogenoalkane, the carbon atom holding the halogen, is
attached directly to three alkyl groups, which may be any
combination of the same or different.
Examples:
2-bromo-2-methylpropane 2-chloro-2-methylpropane
Chemical properties
- Nucleophilic substitution
Halogenoalkanes are much more reactive than alkanes due to the presence of the
electronegative halogens. The halogen-carbon bond is polar causing the carbon to carry a
partial positive and the halogen a partial negative charge
A nucleophilic substitution reaction is one in which a nucleophile attacks a carbon atom
which carries a partial positive charge.
An atom that has a partial negative charge is replaced by the nucleophile
, Nucleophilic substitution of halogenoalkanes (OH−, NH3, primary amines), SN1 and
SN2 mechanisms of nucleophilic substitution, elimination reactions.
Nucleophilic substitution reactions:
1. Reaction with NaOH to form an alcohol
CH3CH2CL+ NaOH → CH3CH2OH + NaCl
Chloroethane + Sodium hydroxide → Ethanol + Sodium chloride
Mechanism: Nucleophilic
Reaction type: Substitution
Conditions: Aqueous + boil under reflux
2. Reaction with ammonia to form amines
Reaction type: Substitution
Mechanism: Nucleophilic
Conditions: NΗ3 in ethanol + heat
Reaction with potassium cyanide to form a nitrile (or cyanide).
CH3Cl + KCN → CH3CN + KCl
Chloromethane cyanide (nitrile)
Reaction type: Substitution
Mechanism: Nucleophilic
Conditions: KCN in water/ethanol + boil under reflux
Elimination Reactions
During an elimination reaction, a bond forms by the removal of two atoms or groups from
the original molecule. In most instances, the bond that forms is a π bond. Elimination
reactions compete with substitution reactions when alkyl halides react with a nucleophile
