Benzene summary Flashcards
(26 cards)
What is an arene?
Anything with a benzene ring.
What is the molecular formula of benzene?
C6H6
Name this compound:
C6H5NO2
Nitrobenzene
Name this compound:
C6H5Br
Bromobenzene
Name this compound:
C6H5Cl
Chlorobenzene
Name this compound:
C6H5C2H5
Ethyl benzene
How many structural isomers of C7H7Br are there?
3
Name the structural isomers of C7H7Br
2-bromomethylbenzene
3-bromomethylbenzene
4-bromomethylbenzene
State 3 uses of benzene
Synthetic fibres
Plastics
Resins
What is meant by the term carcinogenic?
It can cause cancer.
Is benzene carcinogenic?
Yes
What are the 3 problems with Kekules model?
Bond enthalpy
Bond length
Lack of reactivity
Explain why benzenes lack of reactivity disproves Kékule’s model.
It should decolourise bromine in electrophilic additions however, it doesn’t undergo electrophilic addition and it doesn’t decolourise bromine water under normal conditions.
Therefore it has no double bonds in its structure.
Why do the bond lengths of benzene disprove Kékule’s model?
The bond lengths of benzene are all the same however, if Kékule’s model was correct, that shouldn’t be the case.
How do hydrogenation enthalpies disprove Kékule’s model?
The bond enthalpy of benzene should be 3 times the bond enthalpy of cyclohexa-1,3,5-triene however, it is lower than expected and therefore is more stable than anticipated.
Explain Kékule’s model of benzene.
6 carbons with 3 double bonds
6 hydrogens
Why doesn’t benzene undergo electrophilic addition reactions?
It cannot polarise molecules.
What type of reactions does benzene undergo?
Electrophilic substitution.
What type of reaction is the nitration of benzene?
Electrophilic substitution
What are the conditions for the nitration of benzene?
50degrees C
Concentrated nitric acid
Concentration sulfuric acid catalyst
What is the molecular formula for nitric acid?
HNO3
What is the molecular formula for sulfuric acid?
H2SO4
What is used to maintain the steady temperature in the nitration of benzene?
A water bath
What happens if benzene is nitrated at higher temperatures?
Dinitrobenzene
