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U14A2 Learning aim B: Understand the reactions and properties of aromatic compounds
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P3: Explain the chemical properties of industrially important benzene and monosubstituted benzenecompounds.
Halogenation the chlorine or the bromine reacts with the benzene the presence of the Lewis acids like that of
the Ferris or that of the AlCl3 that tends to behave as the catalyst this then forms the chlorobenzene or
bromobenzene.
Sulphonation
The hydrogen atom of the benzene tends to be replaced by the sulphonic acid group (SO3H). As such the
benzene tends to be heated with the concentrated sulphuric acid at 120oC whereas the benzene of the
sulphonic acid tends to be produced by the water.
Nitration
Benzene tends to react with the nitrating mixtures of the HNO3 + H2SO4 at 60 degrees to give the
nitrobenzene
Friedel crafts Alkylation
The benzene tends to react with the alkyl halid in the presence of the Lewis acids like AlCl3 to forming the
alkylbenzene and this addition is often called the alkylation
Acylation
Benzene reacts with the acid chloride like that of the acteyl chloride in the presence of Lewis acids like that
of the AlCl3 and ketone tends to be formed
Reaction with oxygen - Combustion
Benzene
It is highly inflammable, and it will burn with a flame like sooty. Benzene likes to be replaced by the
substitution reaction.
Combustion of the benzene and it will burn with the sooty flame with evolution of the CO2
C6H6 + 15/2 O2. → 6CO2 + 3H2O
As such when the benzene it can show the resonance where it tends to exist in the different forming of the
positioning of the double bond. Also, this property of the benzene and make it stable. As such the benzene
will not undergo for the addition of the reactions, but it will undergo of the substitution of the reactions.
Combustion of the benzene carbon dioxide and water are produced that the benzene burned in oxygen –
benzene burns incompletely especially in the presence of the oxygen as such it wont be consumed so much.
This is due to the molecules that tend to have carbon content that tends to be high as such this will make it
the complete combustion for it. Because of the oxygen to hydrocarbon ratio tends to be high. Because if
there isn’t enough oxygen then the hydrogen within the hydrocarbon tends to use the oxygen that tends to be
available. As such this makes the result of the carbon having to create the carbon monoxide. As such the
flames tends to be produced that are dense with the particles of that is the carbon as such this makes it
increased to the smoky flames.
Addition reactions - Chlorination
Unit 14: Applications of Organic Chemistry Page 1 of 38
,It needs the presence of the UV light, but this is without the catalyst of the benzene through the addition of
the reaction with either the bromine or the chlorine. As such the ring will be delocalised and it will be
permanently broken as such with the chlorine or of the bromine atoms that tends to be added for the atoms of
each carbon.
Because if the bubbles with the chlorine gas will go through the hot benzene as such will be exposed to UV
light for the hour and will be the result of 1,2,3,4,5,6-hexachlorocyclohexane.
Addition Reaction – Hydrogenation
This is diagram shows the addition of the reaction that the hydrogen of the atoms tends to be added to the
benzene ring and the cycloalkane tends to be formed, this will then form the cycloalkane
This shows the reaction that tends to have the hydrogen that is added to the reactants and for that reason the
hydrogen is added to the ethene as such producing the ethane. Because when the hydrogenating of that the
benzene tends to show when using the cyclohexene. As such when the hydrogen is added to the cyclohexene
and then will produce the cyclohexane – this shows the double breaks and single bonding that tends to
replace and that the double breaking and the single bonding and replacing of it because this happens the
resulting is CH group and then tends to become the CH2+. Because the double bonding tends to be broken in
the enthalpy change of at least -120kJmol-1. As such there is one mole of the cyclohexene that tends to be
reacted as for that 120kJ of the heat energy tends to be released. Because of that the ring of the cyclohexene
tends to have two double bonds that tends to have twice as many bonds as such tends to be broken that tends
to arise as such shows the heat energy that is released that is double. Furthermore, the enthalpy change tends
to be -360kJ this is used in the theory of Kekule – the benzene there are three times as such that the bonds
tends to be broken in the cyclohexene. Henceforth, the Kekules’ enthalpy change that is -208kJmol-1 as such
that is out of within prediction and then this makes the actual benzene tend to be around the 150kJmol-1 this
makes it more stable than that of the Kekule. In summary, the delocalisation energy of the benzene tends to
be greater than that of the actual benzene.
Addition reactions with hydrogen, chlorine
This is presenting of the UV light (ultraviolet light), this works without the catalyst as such the benzene will
be hot and this shows that it’s the addition reaction of the chlorine or of the bromine. For that reason, the
delocalisation is that its broken and that the chlorine or of that is the bromine atoms that tend to work over of
the carbon atom.
Unit 14: Applications of Organic Chemistry Page 2 of 38
,This figure shows the reaction that has occurred that the bubble chlorine gas tends to be hot and then will be
exposed to the UV light as such this will form the 1,2,3,4,5,6-hexachlorocyclohexane.
Halogenation of benzene
The catalyst of this is presented and that the benzene is reacted with that is chlorine as such that is of the
hydrogen atoms for that is benzene ring that is being replaced with that is a chlorine atom instead.
Furthermore, the reactions tend to take place that is at room temperature and that tends to be catalysed by
aluminium chloride or that is the iron. As such that the product is known as the chlorobenzene that will be
formed. Because of this the two components that tends to be reacted with each other as such this depends
either if the iron or the aluminium chloride is present.
Substitution Reaction – H2SO4 acid
The electrophilic substitution reaction between benzene and sulphuric acid
The sulphonating benzene
The heat benzene tends to be under the reflux of the concentrated of the sulphuric acid for a long period and
then as it warms the benzene under the reflux of the 40oC with the fuming of the sulphuric acid for 20-30
minutes at least. Because of this the diagram shows the product benzene sulphonic acid
And then this forms the electrophile that is the sulphur trioxide of SO3 as such this shows for the
sulphonation reaction
Unit 14: Applications of Organic Chemistry Page 3 of 38
, Sulphonation
This is when the substitution of the hydrogens of the benzene ring of the sulphonic acid that is called
sulphonation
C6H6 + H2SO4 → C6H5SO3H + H2O
As such to produce the benzene sulphonic acid and for that the benzene can be heated that is under the reflux
with such high concentration of sulphuric acid for long time
Sodium benzene sulfonate pyrolysis
The benzene of it is the sulfonic acid that is reacted with the aqueous sodium hydroxide of the procedure as
such that the resultant salt that tends to be fused at high temperature with the solid sodium hydroxide and this
will show the producing of the sodium phenoxide as such that is acidified with the aqueous acid as such by
producing phenol
(PUBLISHING, 2018)
Substitution Reaction – Alkylation
A catalyst will be increasing for the positive nature of the electrophile and then it makes it better for the
attacking of the benzene rings and then the AlCl3 will then behave as a Lewis Acid, and it will break the C-
Cl bond
The alkylation this tend to be involved for the substitution of the alkyl group, because of this the reagents
that of the halogenoalkane, the RX this is for the compounds for doctor prescribed medication, as such this is
the anhydrous aluminium chloride that is of the AlCl3, as such the conditions will be at room temperature
and for that reason is that it will be dry for it to be inert solvent, the electrophile is that of the carbocation that
is the ion of R+ this letter is commonly used in chemistry. To show this happening is by the equation: C6H6
+C2H5Cl → C6H5C2H5 + HCl. This reaction is shown by the figure below – this shows that the catalyst
shows that by increasing that the positive nature of the electrophile tends to show like that of benzene rings
as when attacking because the aluminium chloride tends to behave as the Lewis Acid as such this shows that
it will break of the C-Cl bond. The catalyst is used for the increasing the positive for the nature of the
electrophile and for that the attacking benzene rings. For that reason, AlCl3 Lewis Acid as such for that
breaking C-Cl bond. Catalyst for that anhydrous aluminium chloride for that the Al as such in the AlCl3 for
that six electrons in its outer shell for that Lewis Acid as such that increases the polarisation of the C-Cl bond
Unit 14: Applications of Organic Chemistry Page 4 of 38
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