Chapter 7

Question 1

What type of radical is most stable

Answer 1

tertiary radical

Question 2

homolytic bond dissociation energies (BDE)

Answer 2

• the amount of energy needed to break a bond homolytically

- the amount of energy released when the bond forms

Question 3

what are energies in terms of bond breaking reactions?

Answer 3

energies are enthalpies of bond breaking reactions

Question 4

what is cracking/pyrolysis

Answer 4

the process of large hydrocarbons breaking down into smaller hydrocarbons or alkenes

Question 5

what can radical fragments combine to form

Answer 5

alkanes and alkenes

Question 6

what are the three steps in the pyrolysis of alkanes

Answer 6

• chain initiation
• chain propogation
• chain termination

Question 7

the role of radicals in aging

Answer 7

• radicals react with fatty acids in the lipid of cell membrane
• the cell is then not able to completely eliminate waste material or take up O2 and nutrients efficiently

Question 8

trend in carbocation stability

Answer 8

methyl

Question 9

inductive effect

Answer 9

resonance delocalization of sigma bonding electrons

Question 10

hyperconjugation

Answer 10

p orbital overlap

Question 11

what is the intermediate of carbocation called

Answer 11

alkyl oxonium ion intermediate

Question 12

elimination reaction general objective

Answer 12

double-bond formation from ROH or RX

uses a weak base (presence of aqueous sulfuric or phosphoric acid)

Question 13

E1

Answer 13

• unimolecular
• hydrogen is deprotonated from the beta position
• this results in alkene formation from a carbonation intermediate
• favored by tertiary

Question 14

E2

Answer 14

• bimolecular
• deprotonation of hydrogen from the beta position
• results in alkene formation
• no carbonation
• favored by primary carbons

Question 15

tertiary rnx in presence of strong base favors

Answer 15

favors E2 over E1

Question 16

zaitsev’s rule

Answer 16

to predict regioselectivity

• the more stable alkene is formed
• deprotonation occurs at the carbon with the LEAST number of hydrogens

Question 17

regioselectivity

Answer 17

preferential bond formation/bond breaking in one direction over others

(think major and minor)

Question 18

relationship between substituted alkenes and stability

Answer 18

the more substituted the alkene, the more stable it is

-because more electrons are being donated

Question 19

the special thing about the rearrangement

Answer 19

can only occur one carbon away

occurs to become more stable => secondary to tertiary

Question 20

hydride and alkul shift

Answer 20

migration can occur in media with poorly nucleophilic conjugate bases, for example:
HSO4-
H2PO4-