Final Notes

Question 1

Definition of a good base

Answer 1

Its conjugate acid has a pKa greater than 11

Question 2

Is ethanol a weak or strong base?

Answer 2

Weak

Question 3

Lewis base

Answer 3

Electron donor, nucleophile

Question 4

Bronsted Lowry base

Answer 4

Proton acceptor, base

Question 5

Can you do an elimination reaction on a substituent in a chair’s equatorial position?

Answer 5

NO! It must be in AXIAL to be antiperiplanar so the elimination can occur

Question 6

What kinds of molecules are optically active in polarimetry?

Answer 6

Chiral ones

Question 7

What kinds of molecules are optically inactive in polarimetry?

Answer 7

Achiral ones

OR a perfectly racemic mixture of R and S chiral molecules

Question 8

“Strong base” in this class means…

Answer 8

Bronsted-Lowry base

Question 9

“Strong nucleophile” in this class means…

Answer 9

Lewis base

Question 10

If a molecule is both a strong base and a strong nucleophile, which of these potential actions takes priority?

Answer 10

Strong base. It’ll primarily act to remove a proton

Question 11

Why are the H’s on terminal alkynes weakly acidic?

Answer 11

It’s due to the increased S character of their sp hybridized bond

Question 12

What things can deprotonate a terminal alkyne?

Answer 12

Any strong bases stronger than the alkyne itself

Question 13

Enol form

Answer 13

Double bond between two carbons

Question 14

Keto form

Answer 14

Double bond between C and O

Question 15

Why does tautomerization happen?

Answer 15

Happens because the sum of the bond energies in the keto form is greater than that of the enol form. BEcause the keto form makes stronger bonds (hence the higher bond energies), the keto form is more stable

Question 16

Definition of keto-enol tautomerization

Answer 16

H and a pair of electrons migrate to form a more stable aldehyde/ketone

Question 17

Alpha carbon

Answer 17

Carbon attached to the leaving group in an elimination rxn

Question 18

Beta carbon

Answer 18

Carbons one carbon away from the alpha carbon

Question 19

E2 Regiochemistry

Answer 19

Follows Zaitsev’s rule, which states that when the reaction uses an unhindered base, the major product will be the most substituted alkene

Question 20

What types of products form in elimination reactions?

Answer 20

Two types of products:

Zaitsev product: more substituted alkene, forms in rxns with unhindered bases

Hofmann product: less substituted alkene, forms in rxns with bulky hindered bases

Question 21

What elimination product forms when an unhindered base is used?

Answer 21

Zaitsev product, more substituted alkene

Question 22

What elimination product forms when a bulky hindered base is used?

Answer 22

Hofmann product, less substituted alkene

Question 23

E2 stereoselectivity

Answer 23

The H and LG must be antiperiplanar in order to achieve proper orbital alignment

For cyclohexane substituents, the LG must be in an axial position to be antiperiplanar

Question 24

Antiperiplanar

Answer 24

Anti and coplanar, 180 degrees across from each other

Question 25

How does branching at alpha and beta carbons affect the rate of Sn2 reactions?

Answer 25

Slows down Sn2 rxns

Question 26

How does branching at alpha and beta carbons affect the rate of E2 reactions?

Answer 26

Speeds up E2 rxns

Question 27

What quality do Sn2 rxns favor for their nucleophiles?

Answer 27

Greater nucleophilicity, electron donor lewis base

Question 28

What quality do E2 rxns favor for their nucleophiles?

Answer 28

Greater basicity, proton acceptor Bronsted-Lowry base

Question 29

Does heating favor elimination or substitution reactions?

Answer 29

Elimination

Question 30

E1 Regiochemistry

Answer 30

Also follows Zaitsev's rule, the major product is the most substituted alkene

Question 31

E2 kinetics

Answer 31

[RX][base]

Question 32

E1 kinetics

Answer 32

[RX] (same as Sn1 rxns)

Question 33

E1 stereochemistry

Answer 33

No alignment required for E1 E alkenes are favored over Z alkenes, as trans is more stable than cis

Question 34

When will the reaction products be a mix of Sn1 and E1?

Answer 34

When the substrate is a 2ndary or 3ary carbocation

Question 35

Strong nucleophile, weak base

Answer 35

Sn2

Question 36

Weak nucleophile, weak base

Answer 36

Sn1 or Sn1/E1

Question 37

Strong nucleophile, strong base

Answer 37

Sn2 or E2

Question 38

Weak nucleophile, strong base

Answer 38

Sn2 or E2

Question 39

How many possible stereoisomers does a molecule have?

Answer 39

2^n, where n = the number of chiral centers This is the max amount, there may be fewer