Final New Information

Question 1

Why are esters more stable than ketones and aldehydes?

Answer 1

Esters have a conjugated system

Question 2

Why does oxidation of an ester require 2 equivalents of organometallic?

Answer 2

the -OCH3 leaving group will depart and a ketone will form

the ketone is more reactive than an ester, so the reaciton will happen again

Question 3

What is the least electrophilic carbonyl in oxidation?

Answer 3

amide

Question 4

Why is an amide the least electrophilic carbonyl in oxidation?

Answer 4

It has the most basic pair of electrons

These electrons contribute to competing resonance the most and “go into” the pi-system

This reduces the electrophilicity of the carbonyl

Question 5

What is the most reactive carbonyl in nucleophilic acyl substitution?

Answer 5

Amide> acid anhydride> amide

Have good leaving group so reactive for nucleophilic acyl substitution because a leaving group will leave

Question 6

When are metal hydrides used?

Answer 6

Metal hydrides are used to reduce a carbon

Question 7

Examples of metal hydrides

Answer 7

NaBH4

LiAlH4

Question 8

Why is LiAlH4 a stronger reducing agent?

Answer 8

LiAlH4 is a stronger reducing agent because of it higher HOMO since Al is less electronegative than B

Also Al is bigger so it able to better take extra electrons

Question 9

Do reducing agents act as nucleophiles or electrophiles?

Answer 9

Reducing agents act as nucleophiles

Question 10

What happens when carbon is oxidized?

Answer 10

When carbons are oxidized they lose electrons

Ex: Alcohol to ketone (+1 to +2 = losing electrons)

Question 11

What metal hydride do we need to use to reduce an ester?

Answer 11

We need to use LiAlH4 to reduce an ester

Since esters are conjugated they require a stronger metal hydride in order to be reduced

Question 12

What metal hydride do we need to use to reduce an ester?

Answer 12

We need to use LiAlH4 to reduce an ester

Since esters are conjugated they require a stronger metal hydride in order to be reduced

Question 13

What molecule is used to oxidize an organic molecule?

Answer 13

Use CrO3

Remember: oxidation is loss (going from alcohol to ketone)

Question 14

What does chromate oxidation of a 1º alcohol produce?

Answer 14

a carboxylic acid

Question 15

How does chromate oxidation of a 1º alcohol produce a carboxlyic acid?

Answer 15

through a hydrate intermediate

Question 16

Ozone molecule structure

Answer 16

a 1,3-dipole through resonance

one end of the molecule has a positive charge and one end has a negative charge

Question 17

What is the pi-system of ozone?

Answer 17

3 psi orbitals

HOMO: psi-2 (non-bonding node in the middle)
LUMO: psi-3

Question 18

What are the interacting orbitals in ozonolysis?

Answer 18

Either O3 LUMO and piCC

Or O3 HOMO and pi*CC

(both homo lumo sets occur)

Question 19

Why is the primary ozonide less stable than secondary ozonide?

Answer 19

the primary ozonide has 2 unstable o-o bonds

the secondary ozonide only has 1 unstable o-o bond

Question 20

When does workup matter?

Answer 20

Workup matters in ozonlysis

Question 21

Oxidative workup

Answer 21

H2O2

Will turn aldehydes into carboxylic acid

Question 22

Reductive workup

Answer 22

Me2S

Aldehydes will remain aldehyde

Question 23

Hydrogenation

Answer 23

Turns alkene into alkane

Question 24

Reactants of hydrogenation

Answer 24

1) Alkene
2) H2
3) Metal (Pd or Pt)

Question 25

Stereoselectivity of hydrogenation

Answer 25

H2 will attack syn

Question 26

Why is a metal needed for hydrogenation?

Answer 26

Homo/lumo of H2 can line up with the metal’s d-orbital

Question 27

What is the energy required to go from an butene to an butane with H2?

Answer 27

28.6 kcal/mol

Question 28

What is the energy required to go from 1,3-butadiene to two alkanes?

Answer 28

55.4 kcal/mol

not just two times 28.6 kcal/mol since the system is conjugated

Question 29

hemiacetal

Answer 29

two -OH groups on same alcohol

unstable intermediate

Question 30

What does CrO3 allow for?

Answer 30

Oxidation of alcohol (alcohol to ketone)

Question 31

What is the BDE of H2?

Answer 31

104 kcal/mol

Question 32

Is Aluminum/Transition metals more or less electronegative than hydrogen?

Answer 32

Less electronegative than hydrogen!

Carbon and hydrogen have very similar electronegativities!

Question 33

What does NaH, CH3-I indicate?

Answer 33

Something will get deprotonated by H- and then -CH3 will attack where the -H was taken from

Question 34

Do you need to write +enantiomer when doing the products of H2, Pd of alkene?

Answer 34

No

Just make sure groups are SYN

Question 35

Is NaSCH3 a strong or weak base?

Answer 35

A weak base

Question 36

What orbitals mix to make pi- molecular orbitals?

Answer 36

p-orbitals!!

Question 37

Where do Csp and C2p fall on MO diagram?

Answer 37

Above the baseline for Csp3

Question 38

What does the reactant NaCN indicate on a 2º alykl halide?

Answer 38

SN2 reaction

Question 39

What type of solvents indicate an SN1/E1 reaction on a 2º alykl halide?

Answer 39

protic weak bases

H2O, ROH, CO2H

Question 40

What does a strong base indicate on a 2º alykl halide?

Answer 40

E2 reaction

Question 41

What does pentadienyl look like?

Answer 41

Not cyclic! Doesn’t say cyclopentadiene!

Straight line of five carbons with a positive charge on the middle carbon

Conjugated system

Question 42

Which nucleophiles are weak bases, but good nucleophiles? And what do they indicate?

Answer 42

CN-, SCH3-, X-

indicate SN2 reaction at 2º and primary carbons

indicate E2 reaction at 3º carbons