Exam 5

Question 1

Diene

Answer 1

two Alkenes in close proximity

Question 2

Cumulated Diene

Answer 2

the double bonds are linked

Question 3

Conjugated Diene

Answer 3

the double bonds are separated by a single bond
- has both sp2 and sp3 character
- can form resonance

Question 4

Diene Stability

Answer 4

• Trans conformation is more stable
• Cis conformation (half a ring) is less stable
• More substituted double bond is chosen

Question 5

1,2- Addition

Answer 5

• Concerted
• Kinetic product

Question 6

1,4- Addition

Answer 6

• Requires an addition of heat
• Thermodynamic product
• Reaction must be reversible

Question 7

H-X, -80ºC

Answer 7

1,2- kinetic product

Question 8

H-X, 40ºC

Answer 8

1,4- thermodynamic product
- Resonance

Question 9

Diels-Alder

Answer 9

• Cis Diene and a dienophile make a ring
• Must match the partial negative and partial positive
• Must be 1,2 or 1,4 product for the EDG/EWG

Stereochemistry:
- Reacts to form the endo product, EWG is under the diene when it reacts
- Anything pointing to the right is up

Question 10

Diene

Answer 10

• can be a chain or an open ring
• Must be able to adapt
• Electron donating group (EDG) makes a partial negative
• when flipping the chain into the ring the substituents rotate on the single bond

Question 11

Dienophile

Answer 11

• a double bond with substituents
• Electron withdrawing group (EWG) makes a partial positive

Question 12

Synthesis of Alcohol: Substitution

Answer 12

SN2: NaOH -> -OH
SN1: H2O

Question 13

Synthesis of Alcohol: Alkenes

Answer 13

Mark Addition
A. H2SO4, H2O
B. 1. Hg(AOC)2, H2O
2. NaBH4
Anti-mark Addition (Syn)
C. 1. BH3, THF
2. H2O2, NaOH

Question 14

Synthesis of Alcohol: Alkene -> Diols (two OH groups)

Answer 14

Syn:
A. 1. KMnO4 (Cold)
2. H2O
B. OsO4, H2O2
Trans:
C. 1. mCPBA
2. H2SO4. H2O

Question 15

:H- Nucleophile

Answer 15

• NaBH4
• LiAlH4
• Reacts with an acid

Question 16

NaBH4

Answer 16

• Weaker
• Reacts with only ketones and aldehydes

Question 17

LiAlH4

Answer 17

• Stronger
• Reacts with all carbonyl functional groups

Question 18

Reduction of Esters with :H- and an acid

Answer 18

adds two :H-
1. :H- reduces the double bonded O
2. Resonance reforms the double bond and pushes off the O group
3. a second :H- attacks

Question 19

Carbon Nucleophiles

Answer 19

R-MgBr
R-Li
R2-CuLi
- Reacts with an acid
-Adds the carbon chain to reduce the ketone/aldehyde to an alcohol
- Adds the carbon chain twice to reduce the ester to an alcohol

Question 20

R-MgBr

Answer 20

• Grignard Reagent
• can react with alkyl halide to make a longer carbon chain and MgBr2

Question 21

Synthesis of ethers: General

Answer 21

• NaO-R -> -:O-R
• R-OH

Question 22

Synthesis of ethers: Williamson Ether (SN2)

Answer 22

1. NaH
2. R-Br

Question 23

Synthesis of ethers: Acid Catalyzed

Answer 23

H2SO4, CH3OH

Question 24

Synthesis of ethers: Oxymercuration

Answer 24

1. Hg(OAC)2, R-OH
2. NaBH3

Question 25

Reactions of Ethers

Answer 25

- Strong Acid (H-X) 1º/2º: 1. O lone pair attacks the H 2. -:X attacks less substituted carbon and gives the electrons to the positive oxygen 3º: 1. O lone pair attacks the H 2. tertiary carbon willingly gives the positive oxygen the electrons in the bond 3. -:X attacks the tertiary carbocation

Question 26

Epoxide Opening to an Ether w/ Acid

Answer 26

H2SO4, R-OH 1. Acid gives the epoxide a hydrogen 2. the R-OH uses its lone pair to attack the more substituted side and opens the epoxide ring

Question 27

Epoxide Opening to an Ether w/ Base

Answer 27

-:O-R, R-OH 1. -:O-R attacks the less substituted side of the epoxide ring opening it 2. a lone pair on the -:O from the newly open epoxide ring takes an H from the R-OH in solution

Question 28

Epoxide Opening to an Ether w/ a carbon nucleophile

Answer 28

Carbon Nucleophile + Acid - attacks less substituted side of the epoxide ring

Question 29

Thiol

Answer 29

CH3-S-H - More acidic than alcohol

Question 30

Thioether

Answer 30

CH3-S-CH3 - Better nucleophile than Ether