benzene Flashcards
(22 cards)
what did kekules equilibrium model of benzene show
that there were alternating double and single bonds in the hexagon structure of benzene
what were the problems with kekules equilibrium structure
-each functional groups bond length is different
-real benzene is more stable (lower enthalpy) than kekules benzene
-doesn’t go through an addition reaction
properties of benzene
-cyclic
-planar molecule
-C6H6
-4 valence e-
-delocalised electrons system
why is benzene resistant to bromination compared to alkenes
-in benzene electrons are delocalised
-in alkenes electrons are localised between two carbones
-benzene has a lower electron density compared to alkene having high electron density
-benzene polarises bromine less and induces a weaker dipole in bromine
reactants and products of nitration
benzene -> nitrobenzene
reagent of nitration
Conc NO2 in the presence of Conc H2SO4 at 60°C
why should temp be kept constant at 60°C during nitration
to stop further additions
equation for the formation of electrophile in nitration
HNO3 + 2H2SO4->NO2+^ + 2HSO4^
+ H3O
reforming catalyst in nitration
H+ + HSO4- -> H2SO4
reagents of halogenation
a halogen
conditions of halogenation
FeBr3 or FeCl3
formation of electrophile in halogenation
FeBr3 + Br2 -> FeBr4- + Br+
or
FrCl3 + Cl2 -> FeCl4- + Cl+
reformation of catalyst in halogenation
H+ + FeBr4- -> FrBr3 + HBr
reactants and products of Alkylation
Benzene-> Akyl Benzene
reagents of Akylation
Choroalkane, FeCl3 or AlCl3
formation of catalyst during akylation
H+ + AlCl4 -> AlCl3- + H+
outcome of Akylation
outcome can be a mixture of products as mechanism can repeat
conditions of akylation
heat under reflux
products and reactants in acylation
benzene -> phenyl ketone
reagents of acylation
AlCl3
conditions of acylation
anhydrous
60’C
30 mins reflux
formation of catalyst in acylation
AlCl4- + H+ -> AlCl3 + HCl
