Chapter 16: The Chemistry of Benzene and its Derivatives Flashcards
Halogenation of Benzene
Nitration of Benzene
Alkyl group
Acyl group
Friedel-Crafts Alkylation
Limitations- can be used with methyl and ethyl groups, after that you have to consider carbocation rearrangement. Also ring must not be severly deactivated
Friedel Crafts Acylation
Clemmenson Reduction
Notes on alkylation
- difficult to install just one alkyl group
- each alkyl addition makes the ring more reactive
Notes on Acylation
- generally impossible to install >1 acyl group
- presence of acyl group makes ring less reactive
Sulfonation
Removing sulfa group
Hydrogenation of Benzene
-takes a huge amount of energy to hydrogenate first DB, but once aromaticity lost, other 2 bonds hydrogenated almost immediately
Activators
- make ring more nucleophilic (donate e- density)
- OH
- alkyl groups (b/c electron donating
Deactivators
- make ring less nucleophilic (withdraw e- density)
- NO2 group
Activators are ___ directors
ortho-para
Deactivators are ___ directors
meta directors
Exception = halogens (deactivators but O/P directors)
How do you decide when there’s more than one director on the ring
- O/P directors always beat meta directors
- Strong activators always beat weak activators
Strong Activators
- groups with lone pair next to aromatic ring
Moderate Activators
- groups w/ lone pair, but where lone pair is already partially tied up in resonance
weak activators
- donate e- density through weak effect called hyperconjugation
- ex-all alkyl groups are weak activators
Weak deactivators
- halogen, induction barely beats resonance
Moderate deactivators
- withdraw e- density via resonance
- all have pi bond to electronegative atom
Strong deactivators
- very powerfully electron withdrawing
Steric directing
- bulky groups usually direct para
