10/24 Flashcards
(25 cards)
what is an activator
it is a group that makes the reaction faster
what is a deactivator
it is a group that makes the reaction slower
what is an activator
it speeds up the reaction
what is a deactivator
it slows down the reaction
what is the effect of an electron donating group on an aromatic ring
by donating electron density to the arenium ion, the carbocation is stabilized and the EDG acts as an activator and speeds up the reaction
electron withdrawing groups act as
they act as deactivators and they slow down the reaction by pulling away electron density and destabilizing the carbocation from the arenium ion
how are activators bonded to the ring
with the atom that has the lone pairs
what do ortho para activators have characteristically?
they have lone pairs on the atom bonded to the ring that can donate electron density into the ring
where does the nitrogen and oxygen have to be on amides and esters in order for it to be a activator?
they need to be directly bonded to the ring
what are the ortho-para activators
ethers, alcohols, amine, amides, esters, alkyls, and phenyl groups
what are the ortho para deactivators
they are halogens
why are halogens deactivators?
they have a withdrawing affect that deactivates the ring and withdraws electrons but they have lone pairs that can perform resonance
what type of action do EWGs perform on rings
they are meta deactivators
what is the trend for meta deactivators
the lone pair cannot be donated
the atom bonded to the ring is positive or partially positive
what happens when you try to add a substituent on aromatic ring with a meta deactivator?
it creates an arenium ion where the positive charges from the ewg and the arenium ion are near eachother and repel
are halogens electron withdrawing or donating
they are both
what is the inductive effect of halogens
it is the ability of a group to pull electron density away from the ring, it is an electron withdrawing property and it deactivates the ring
what is the resonance effect of halogens
it is the ability of the lone pairs on a halogen to perform resonance and stabilize the positive charge
when dealing with the disubstituted rings, which substituent dominates
the electron donating group ortho-para directing affects dominates
what if there are two EDG on a ring
the stronger EDG dominates
what dominates, resonance affects or induction
resonance
what are the disadvantages to friedel crafts alkylations
rearrangements- don’t get expected product
polyalkylations- multiple additions of alkyl groups
why are polyalkylations a problem in friedel crafts
by adding an alkyl group, we introduce an activator that wants to react more and will create mixed products
