Chemistry: Aromatic Chemistry
This flashcard set explores the fundamentals of aromatic chemistry, focusing on benzene and its derivatives known as arenes. It presents key evidence against the Kekulé structure, including bromine water tests, bond length data, and thermochemical stability. It also explains why benzene’s carbon-carbon bonds are intermediate in length, supporting its regular hexagonal structure.
what is aromatic chemistry
the study of benzene and compounds containing the benzene ring
Key Terms
what is aromatic chemistry
the study of benzene and compounds containing the benzene ring
what are compounds containing the benzene ring called
arenes
evidence against the kekule structure of benzene
benzene doesn’t decolourise bromine water (whereas c=c does)
carbon carbon bond lengths (C=c shorter than C-C)
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justfifcation for c-c bond lengths in benzene
bond lengths intermediate- benzene is a regular hexagon- if bonds single double alternating would be irregular
how does thermochemical data for hydrogenation of benzne suggest its more stable than expected
enthalpy is roughly 150kJ/mol more stable than expected
what structure does benzene have
a regular, planar, hexagon structure
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| Term | Definition |
|---|---|
what is aromatic chemistry | the study of benzene and compounds containing the benzene ring |
what are compounds containing the benzene ring called | arenes |
evidence against the kekule structure of benzene |
|
justfifcation for c-c bond lengths in benzene | bond lengths intermediate- benzene is a regular hexagon- if bonds single double alternating would be irregular |
how does thermochemical data for hydrogenation of benzne suggest its more stable than expected | enthalpy is roughly 150kJ/mol more stable than expected |
what structure does benzene have | a regular, planar, hexagon structure |
why does benzene have a regular planar hexagon structure | the six c atoms and the six h atoms are all in the same plane |
what are all bond angles in benzene | 120 degrees |
how are the 6 c-c bond intermediate in length | between length of a c-c and a c=c bond |
how does the pi bond form | overlap of adjacent p orbitals |
where does the pi bond form | above and below the ring |
what is the pi bond essentially | an electron cloud above and below the ring |
where are elections In the pi bond | delocalised |
why are the pi bonds in benzene harder to break than a normal c=c bond | the delocalised structure has extra stability |
which part of the benzene ring attracts electrophile | the pi bond above and below the plane is an area of moderately high electron density |
electrophile | an electron pair acceptor |
what happens in the electrophilic substitution reaction of benzene | a h atom from the benzene ring is replaced by a new group of atoms |
why does benzene undergo substitution rather than addition | to preserve the stability of the delocalised pi bond |
nitration:reagents | conc sulphuric and conc nitric sulphuric is catalyst |
nitration: conditions | below 50 degrees Celsius |
nitration: overall equation | benzene+ nitric > nitrobenzene + water |
nitration: electrophile | nitronium ion NO2+ |
nitration: generation of electrophile equation | H2SO4 + HNO3 > NO2+ + HSO4- + H2O |
nitration: regeneration of catalyst | H+ + HSO4- > H2SO4 |
acylation: reagents | acyl chloride |
acylation: conditions | AlCl3 (halogen carrier) and heat |
acylation: general equation | benzene + acyl chloride > (benzene)-COR + HCl |
acylation: electrophile | RCO + |
acylation: benzene + ethanoyl chloride | generation of electrophile | CH3COCl + AlCl3 > CH3CO+ + AlCl4- |
acylation: benzene + ethanoyl chloride | regeneration of catalyst | AlCl4- + H+ > AlCl3 + HCl |
reaction mechanism cyclohexene and bromine | electrophilic addition |
reaction mechanisms benzene and bromine | electrophilic substitution |
why are the reactions different: benzene |
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why are the reactions different: cyclohexene |
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why is methyl benzene more reactive than benzene with electrophiles |
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why is the nitration of benzene an important reaction | nitrogen containing aromatic compounds have many applications |
uses of nitrobenzene | explosives |
reagents for nitration of benzene | conc nitric and conc sulphuric |
uses of benzene with -NH2 group attached (amine) | dyes and drugs |
how to get from nitrobenzene to benzene with an -NH2 group (amine) | conc hydrochloric | tin catalyst |
what can nitrobenzene be reduced to for | amine |
equation for reduction of aromatic nitro compounds | benzene-NO2 + 6[H] > benzene-NH2 + 2H2O |