Radicals Flashcards
(16 cards)
Describe the stability of a radical
Similar to a carbocation, the more substituted the more stable
What are the steps of radicalization?
Initiation, propagation, termination
What is initiation and what will you commonly see doing so?
This is the creating of a radical. Commonly see cl2 or Br2 do this. An electrons from the shared bond is kicked on to each.
What is propagation?
The number of radicals is conserved. It’s when a radical becomes whole by making a new radical . This can happen until termination
Termination
2 radicals collide
What is free radical halogenation and what are the reagents?
When an r and X2 group react with light (hv) or heat to form a R- X group
What is abstraction and what is its favorability?
It is when a radical id abstracting an Atom from another compound to form a new radical. The most substituted relevant atom is the favored abstraction .
What are the most common atoms to abstract?
H or Cl/ Br
What is special about chlorination?
It’s less selective so all abstraction products will be formed
Describe allylic halogenation and its reagents
An ALKENE reacts with NBS and light (hv) and forms all possible h abstraction sites with Br via sn2
What is abstraction in simple terms?
A substitution of H for a halide
What does least or heat do in the mechanism?
It initiates the radicalization of a x-x bond
What can be said about bromine
It’s selective and will abstract the most substituted atom
What does NBS with light yield when reacted with an alkene?
A Br on the allylic of Benzyllic position.
What is the allylic or benzyllix position?
The carbon adjacent to the pi bond or benzyl group
The reaction of an alkene with HBR and peroxides (ROOR) produces the anti maokovnikov of a HBR reaction. This is in fact a radical rxn. Describe the mechanism
ROOR breaks upset into 2 OR radicals. This reacts with the HBR and forms a new BR radical. This Br radical reacts with the pi bond and goes in the least sub position and thus forms a radical on the other carbon which may undergo rearrangement. More HBR solution comes in and fills the radical
