benzene substituents Flashcards
when do we use NBS
when we want monosubstitution of Br onto the benzylic carbon
what is NCS
NBS with Cl instead of Br
what is the best way to put a halogen onto the benzylic carbon of a benzene
use NBS or NCS
what happens if we react benzyl halides with a strong nucleophile
Sn2 = inversion of chemistry
what happens if we do Sn1 on a benzyl halide
we get a racemic mix
what do we get when benzylic carbons are oxidized
benzoic acids (R –> carboxylic acid group)
what can we use to oxidize
Jones, KMnO4
for oxidation of benzylic carbons, what needs to be on the molecule for the reaction to occur
we need benzylic hydrogens
what happens if we use a MILD oxidizing agent on a benzylic carbon
we get a ketone or aldehyde
how do we get a carboxylic acid from a benzylic carbon
oxidation with a strong ox agent
how do we get a ketone from a benzylic carbon
mild oxidation of a toluene
how do we get an aldehyde from a benzylic carbon
mild oxidation of anything other than a toluene
what do we use to do selective oxidation (ie leaving a terminal OH group alone but reacting a dif. OH group)
we use MnO2 to be selective. OH turns into a ketone, and terminal OH stays the same
what two reactions can we do with benzyl ethers
reduction or oxidation
what do we get by reducing a benzyl ether
toluene
what do we use to reduce benzyl ethers
H2 / Pt
what do we get by oxidizing a benzyl ether
benzoic acid
what do we use to oxidize benzyl ethers
KMnO4 or Jones
how might we produce benzoic acid from a basic benzene ring
pressurize it using CO2
ie use CO2, KHCO3(aq), with pressure
how do we convert nitrobenzene (strong deactivator) to aniline (strong activator)
reduction
- clemmensen (Zn, Hg, HCl)
- H2 Pd/C, or Adams, or Raney Ni
how do we make an aryl cation
oxidize aniline to get an Arenediazonium salt, and then heat it to get the aryl cation
why are arenediazonium salts so useful
they’re the precursors of many products
in what position will the sub be added when it reacts with an arenediazonium salt
para
what happens when we react an azenediazonium salt with another benzene
forms azo compounds: compounds joined by N=N double bond
