Ch 12 Radicals

Question 1

Alkanes are saturated hydrocarbons:

Answer 1

they do not contain any carbon-carbon double or triple bonds

Question 2

Alkanes are unreactive compounds because they have

Answer 2

only strong sigma-bonds and atoms with no partial charges

Question 3

In heterolytic bond cleavage:

Answer 3

a bond breaks so that one of the atoms retains both of the bonding electrons

Question 4

In homolytic bond cleavage:

Answer 4

a bond breaks so that both of the atoms retains one of the bonding electrons

Question 5

Alkanes undergo radical substitution reactions with

Answer 5

chlorine or bromine at high temperatures or in the presence of light to form alkyl chlorides of alkyl bromides

Question 6

Radical chain reaction steps:

Answer 6

initiation, propagation, termination

Question 7

the rate determining step of a radical substitution reaction is

Answer 7

removal of a hydrogen atom to form an alkyl radical

Question 8

The relative stabilities of radicals and their relative rates of formation;

Answer 8

3° > 2° > 1° > methyl

Question 9

Calculation of the relative amounts of products obtained from the radical halogenation of an alkane must take into an account

Answer 9

both the probability of and the relative rate at which a particular radical is formed

Question 10

the reactivity-selectivity principle states that

Answer 10

the more reactive a species is the less selective it will be

Question 11

a bromine radical is less reactive than a chlorine radical

Answer 11

so a bromine radical is more selective about which hydrogen atom it removes

Question 12

Ethers form explosive peroxides when

Answer 12

they are exposed to air

Question 13

A peroxide is a radical initiator because it creates

Answer 13

radicals

Question 14

Radical addition reactions are chain reactions with

Answer 14

initiation, propagation, and termination steps

Question 15

A peroxide reverses the order of H and Br to an alkene because it causes

Answer 15

bromide radical instead of the H+ to be the electrophile.

Question 16

if an reactant that does not have andasymmetric center undergoes a radical substitution or a radical addition reaction that forms a product with an asymmetric center

Answer 16

then racemic mixture will be obtained

Question 17

A racemic mixture is also obtained if a hydrogen bonded to an asymmetric center is

Answer 17

substituted by a halogen

Question 18

allylic and benzylic radicals are more stable than

Answer 18

tertiary radicals

Question 19

NBS is used to brominate

Answer 19

allylic carbons

Question 20

A radical inhibitor (an antioxidant) destroys radicals by

Answer 20

converting them to relatively stable radicals or to compounds that have only paired electrons