Unit 14A: Applications of Organic Chemistry
Functional group chemistry for designer molecules
P1: Explain the reactions of a range of carbonyl and non-carbonyl
functional group compounds
Halogenoalkanes, or also known as haloalkanes they are
compounds that is either one or more hydrogen atoms in an
alkane have been replaced by halogen atoms such as fluorine,
chlorine, bromine, and iodine. Halogenoalkanes go undergo two
reactions nucleophilic substitution and elimination. Nucleophilic
substitution is when the halogens leave the haloalkane and
therefore the nucleophile will get attracted to the positive charge
on the carbon.
Nucleophile donates electron pairs it forms bonds with a positive
carbon atom and also is known to have a negative charged ion. It
can be used to form a covalent bond because it has a lone pair of
electrons.
In these reactions, nucleophiles will replace the halogens in
halogenoalkanes.
Nucleophilic substitution reactions:
1. Hydroxide ion with bromoethane, this will form ethanol
CH3CH2Br + NaOH(aqueous) CH3CH2OH + NaBr
CH3CH2Br + OH-(aqueous) CH3CH2OH + Br-
Mechanism
2. Cyanide with bromoethane, this will form propionitrile
CH3CH2Br + NaCN(aq) CH3CH2CN + NaBr
CH3CH2Br + CN-(aq) CH3CH2CN + Br-
Mechanism
, 3. Ammonia with bromoethane, this will form ethanamine
CH3CH2Br + 2NH3 CH3CH2NH2 + NH4+ Br-
Mechanism
Uses of nitriles:
One of the useful things about nitriles compounds is that they can be
converted to carboxylic acids. This happens when either a strong alkali or a
strong acid is warmed under a reflux.
Nitrile’s hydrolysis: acid hydrolysis of nitriles
CH3CH2CN + 2H2O + H+ CH3CH2COOH + NH4+
Reflux with strong acid propanoic acid
Elimination reactions in halogenoalkanes:
Elimination reactions go under different conditions such as sodium or
potassium hydroxide that is dissolved in ethanol and mixed with the
halogenoalkane and heated.
CH3CHBrCH3 + OH- CH3CH CH2 + H2O + Br- (in ethanol)
Elimination of HBr from 2-bromopropane:
Mechanism:
, Elimination versus substitution:
Nucleophilic substitution: RCH2CH2OH + X- + OH- (aqueous) hydroxide acts as
a nucleophile.
Elimination: RCH2CH2X + OH- (ethanol)
RCH CH2 + H2O + X- (alkene) this acts as a base
Alcohols- alcohols are known as compounds that is either one or
more hydrogen atoms have been replaced in an alkane by the -OH
group. Alcohols can be oxidized in order to give ketones,
aldehydes and carboxylic acids. This can result in increasing the
number of bonds from carbon to oxygen or it can decrease the
number of bonds to hydrogen.
o Examples:
There are 3 types of alcohols. Those types depend on how the -OH group is
positioned on the chain of carbon atoms.
Primary alcohols:
In this type, the carbon which carries the -OH group is only attached to
one alkyl group.
Functional group chemistry for designer molecules
P1: Explain the reactions of a range of carbonyl and non-carbonyl
functional group compounds
Halogenoalkanes, or also known as haloalkanes they are
compounds that is either one or more hydrogen atoms in an
alkane have been replaced by halogen atoms such as fluorine,
chlorine, bromine, and iodine. Halogenoalkanes go undergo two
reactions nucleophilic substitution and elimination. Nucleophilic
substitution is when the halogens leave the haloalkane and
therefore the nucleophile will get attracted to the positive charge
on the carbon.
Nucleophile donates electron pairs it forms bonds with a positive
carbon atom and also is known to have a negative charged ion. It
can be used to form a covalent bond because it has a lone pair of
electrons.
In these reactions, nucleophiles will replace the halogens in
halogenoalkanes.
Nucleophilic substitution reactions:
1. Hydroxide ion with bromoethane, this will form ethanol
CH3CH2Br + NaOH(aqueous) CH3CH2OH + NaBr
CH3CH2Br + OH-(aqueous) CH3CH2OH + Br-
Mechanism
2. Cyanide with bromoethane, this will form propionitrile
CH3CH2Br + NaCN(aq) CH3CH2CN + NaBr
CH3CH2Br + CN-(aq) CH3CH2CN + Br-
Mechanism
, 3. Ammonia with bromoethane, this will form ethanamine
CH3CH2Br + 2NH3 CH3CH2NH2 + NH4+ Br-
Mechanism
Uses of nitriles:
One of the useful things about nitriles compounds is that they can be
converted to carboxylic acids. This happens when either a strong alkali or a
strong acid is warmed under a reflux.
Nitrile’s hydrolysis: acid hydrolysis of nitriles
CH3CH2CN + 2H2O + H+ CH3CH2COOH + NH4+
Reflux with strong acid propanoic acid
Elimination reactions in halogenoalkanes:
Elimination reactions go under different conditions such as sodium or
potassium hydroxide that is dissolved in ethanol and mixed with the
halogenoalkane and heated.
CH3CHBrCH3 + OH- CH3CH CH2 + H2O + Br- (in ethanol)
Elimination of HBr from 2-bromopropane:
Mechanism:
, Elimination versus substitution:
Nucleophilic substitution: RCH2CH2OH + X- + OH- (aqueous) hydroxide acts as
a nucleophile.
Elimination: RCH2CH2X + OH- (ethanol)
RCH CH2 + H2O + X- (alkene) this acts as a base
Alcohols- alcohols are known as compounds that is either one or
more hydrogen atoms have been replaced in an alkane by the -OH
group. Alcohols can be oxidized in order to give ketones,
aldehydes and carboxylic acids. This can result in increasing the
number of bonds from carbon to oxygen or it can decrease the
number of bonds to hydrogen.
o Examples:
There are 3 types of alcohols. Those types depend on how the -OH group is
positioned on the chain of carbon atoms.
Primary alcohols:
In this type, the carbon which carries the -OH group is only attached to
one alkyl group.
