Week 1/2

Question 1

Heterolytic bond cleavage

Answer 1

• when bond broken heterolytically, the e- are shared unevenly
• The atom that takes the e- with it is the leaving group

Question 2

Heterolytic bond formation

Answer 2

-when two atoms are forming a bond, the e- are coming from one source

Question 3

Electrophile

Answer 3

• e- deficient
• accepts a pair of e- to form bond
• can be called lewis acid

Question 4

Nucleophile

Answer 4

• e- rich species
• donate pair of e- to form bond
• can be called a lewis base

Question 5

Examples of nucleophiles

Answer 5

• hydroxide
• cyano (N-C-, triple bond, neg charge on C)
• amine (NH3)
• Thiol (H-S-R)
• Thiolate (R-S-, neg charge on S)

Question 6

Determining electrophiles

Answer 6

• missing a pair of e- (ie. carbocation)
• R-X has polarized bond connected to good LG
• LG must be good e- acceptor, ie. conjugate base of strong acid

Question 7

Substitution rxn transition state

Answer 7

∆G‡ is inversely proportional to the rate constant

• transition states can’t be isolated due to instability
• lifetime of less than a bond vibration
• partial bonds occur

Question 8

Gibbs Free energy equation

Answer 8

∆G˚=-RTln(Keq)

Question 9

Productive orbital interactions

Answer 9

• similar relative energy of reacting orbitals
• good alignment of reacting orbitals
• Only HOMO of nucleophile and LUMO of electrophile close enough in energy to react
• Nu and E+ react b/c of energy release when new bonding orbital is formed

Question 10

HOMO LUMO interactions

Answer 10

-Large HOMO/LUMO energy gap results in small energy release, vise versa for small HOMO/LUMO gap

Question 11

Racemic mixture

Answer 11

50: 50 mixture of stereoisomers

- hallmark of SN1