A2 things to learn Flashcards
three bits of evidence against kekules benzene
- doesnt easily undergo electrophilic addition
- bond length of all bonds is the same when it should be three sigma and three pi
- enthalpy of hyrdogenation is less than expected
what are the reagents and conditions for the halogenation of benzene
Cl and halogen carrier (catalyst)
FeCL3 or AlCl3
reagents for nitration of benzene
conc. nitric acid and conc. sulphuric acid (catalysts)
what does freidel-crafts allow you to do?
add carbon chains to benzene rings
alkylation using a haloalkane, what do you do
where the halogen is, add the benzene ring and make the halogen bond with the lost H
alkylation with an acylchloride, what do you do
where the halogen is, add the benzene ring and make the halogen bond with the lost H
why is phenol more electron dense than benzene?
there is a LONE PAIR in the P ORBITAL OF THE OXYGEN that overlaps with the p orbital in benzene so the electrons are PARTIALLY DELOCALISED INTO THE RING
how does phenol react with bromine (aq)
no catalyst needed (halogen carrier)
so easy multiple substitutions occur
it happens on carbons 2, 3 and 6
how does phenol react with nitric acid
no catalyst
forms a mix of 2-nitrophenol and 4-nitrophenol
how does phenol react with water?
it partially dissolves because the OH can make hydrogen bonds but the benzene ring can only make induced dipole-dipole interactions
it also forms a weak acid, more strong than aliphatic alcohols because the ring weakens the OH bond and makes it easier to lose the H
how does phenol react with sodium hydroxide
it forms a salt: C6H5O-Na+ (aq)
how does phenol react with sodium
it forms an ionic salt: C6H5O-Na+ (s)
how does it react with metal carbonates
IT DOES NOT
it is a way to distinguish phenol from carboxylic acids
they both react with sodium and sodium hydroxide but phenol doesn’t react with metal carbonates
in phenol what carbons do things substitute on to
2 4 6
in a benzene with an NH2 group what carbons do things substitute to
2 4 6
