A2 Chemistry Topic 18 Questions - Organic

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Describe the structure in Benzene
It has a perfect hexagonal planar shape. Each Carbon forms 2 C-C bonds, 1 C-H bond and the final pz orbital electron forms a bond with other pz orbitals to form a delocalised pi electron system. This delocalised pi system stabilises the carbon ring.
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List 3 pieces of Evidence for Structure of benzene
Xray Diffraction, Hydrogenation/Thermochemical change (Stabilisation Energy of 150kJmol), Lack of reaction with electrophiles, Lack of 1,2 Dichlorobenzene isomers (Kekule's Structure), Infrared Spectrometry
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Why is Benzene more 'stable' than should be?
Ring of delocalised pi electron system stabilises the carbon ring, as well as reducing it's reactivity with nucleophiles. Has a RESONANCE STABILITY of 150kJmol-1
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Conditions to convert Benzene to Cyclohexane
3xH2, Raney Nickel, 200 Celcius
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State the differences between the conditions for halogenating Benzene and Phenol with Bromine
Benzene requires a Catalyst (Fe/FeBr3), and does electrophilic substitution under heat in anhydrous conditions. Phenol reacts at R.T. without a catalyst to form a WHITE precipitate (2,4,6 tribromophenol) (can be aqueous)
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Name the type of reaction and reagents required to convert Benzene to Methyl Benzene
Friedel-Craft Alkylation Reaction, Al/ AlCl3 catalyst, chloromethane
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Give the type of reaction, conditions for the reaction of Benzene to 1-Phenylpropan-1-one
Fridel-Craft Acylation Reaction, AlCl3, Propanoyl Chloride
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Give the differences of Nitration between Benzene and Phenols.
Benzene: Conc Sulphuric acid, Conc Nitric acid, 55 Celcius, Phenol: Conc Nitric acid, forms 2 isomers 2/4 - nitrophenol, Is a BROWN mixture.
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Why does Phenol react differently from Benzene
Phenols are more reactive, due to increased electron density in the delocalised pi system. The lone pairs from the -OH get pulled into the ring, resulting in a stronger reaction with electrophiles.
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Difference between the reactivity Pentanol and Phenol
Phenols are less reactive with nucleophiles due to increased electron density, however alcohols are less reactive with electrophiles. Phenol reacts more as an acid due to the increased positive charge on the O in OH as the lone pair gets pulled away.
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Difference in the physical properties between Benzene and Phenol
M.P. of phenol is 41 Celcius, M.P. of benzene is 5.5 Celcius. Phenol can form hydrogen bonding while the strongest intermolecular force benzene has is london forces. Phenol only dissolves at 66 celcius
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State the number of chiral carbons and different H1 NMR environments there are in 3-phenol, 2-amino propanoic Acid
1 chircal carbon on c2 of propanoic acid, 7 Hydrogen environments.
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Other cards in this set

Card 2

Front

List 3 pieces of Evidence for Structure of benzene

Back

Xray Diffraction, Hydrogenation/Thermochemical change (Stabilisation Energy of 150kJmol), Lack of reaction with electrophiles, Lack of 1,2 Dichlorobenzene isomers (Kekule's Structure), Infrared Spectrometry

Card 3

Front

Why is Benzene more 'stable' than should be?

Back

Preview of the front of card 3

Card 4

Front

Conditions to convert Benzene to Cyclohexane

Back

Preview of the front of card 4

Card 5

Front

State the differences between the conditions for halogenating Benzene and Phenol with Bromine

Back

Preview of the front of card 5
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