Benzene Flashcards
Formula of benzene
C6H6
Structure of benzene info.
Delocalised pi orbitals, etc.
Nitration of benzene mechanism
Reagents:
- Concentrated nitric acid
- Concentrated sulphuric acid
- Heat to 50 Degrees Celsius
Formation of NO2+ ions:
- H2SO4 + HNO3 —>(Reversible) [H2NO3]+ + H2SO4-
- [H2NO3]+ —>(Reversible) H20 + NO2+(nitronium ion)
Electrophilic substitution:
- NO2 acts as an electrophile in electrophilic substitution
- Benzene pi bond(ring) attacks the electrophile(positive ion)
- etc.
Overall:
-Benzene + Nitric acid(HNO3) —> Nitro benzene + water
Method to purify a solid compound
Recrystallisation
How to test for purity of a substance
- Chromatography
- If pure, only one substance separates on filter papers
- if impure, more than one substance will separate out
Melting Points:
- If substance is pure, it will all melt at one fixed temperature
- If substance is impure, it will all melt over a range of temperatures
Mechanisms of recrystallisation
H
Recrystallisation 6 mark question -
H
Why do we purify products of organic synthesis?
-To increase atom economy
-To remove harmful substances from your organic molecule - e.g. makes medicines safer, less harmful
E.g. removal of sulphuric acid from 3-nitromethylbenzene
Thin layer chromatography mechanism
H
Stationary phase def
H
Mobile phase def
H
Rf value def
H
When does benzene becomes named as a phenol?
- When another functional group is attached, e.g. OH
- when a carbon chain of 8 carbons or more is attached
