Ch 11 HW (Radicals)

homolytic cleavage

1 unpaired electron to both

most stable radical

tertiary, low bond strength, lots of resonance

other ways to say low bond association energy

• why H is most likely to be plucked off

• where is the most likely place to form a radical

• where is the most likely place to add a carbocation

if an unpaired electron is adjacent to a double bond does that make it more or less stable than an unpaired electron that is further from a double bond

it makes it more stable

structures in order of highest to lowest stability

benzene, allylic, substitution

is allylic more stable than tertiary

yes

how to determine which C-H bond is the weakest

the one that is most likely to come off

hydrogen abstraction

propagation, H is taken by another molecule

coupling

being brought together

addition to a pi bond

unpaired electron goes to where pi bond was and the other electron becomes a methyl

elimination

radical becomes two separate

radical termination

2 radicals form a nonradical

initiation

• radical formed from non radical

• homolytic cleavage

a propagation step

hydrogen abstraction

termination step

coupling

propagation steps

• hydrogen abstraction

• halogen abstraction

• addition of a pi bond

• elimination

monochlorination

addition of one chlorine

initiator

homolytically cleaves with heat or light

what does it mean if an initiator has lower temperature

theres less energy

if it is tertiary and has more resonance would it be a good initiator

yes because it requires less energy

propagation step

addition of a pi bond, halogen abstraction, hydrogen abstraction, elimination

generates a radical

termination

forms a non radical

coupling

if a compound has more chlorine will it want more chlorine

yes, so in order of most reactive to least:

1) chloroform

2) dichloromethane

3) chloromethane

4) methane

how is chloroform formation minimized

using less chlorine and more of something else like ethane

is bromination or chlorination slower

bromine is more selective so it is slower since it needs to go to a specific carbon whereas chlorine will go to whichever random ones are available

rate determining step

is the slowest step

what mechanism is the slowest step

hydrogen abstraction

which of the following statements correctly describes the transition state for the rate-determining step in the free-radical bromination of methane

the transition state resembles more products than reactants

what functions as an antioxidant

phenol

propagation

forms a radical from a radical and a non radical

termination

two radicals form a non radical