Unit 1

Question 1

diastereotopic hydrogens

Answer 1

chemically nonequivalent and thus give different chemical shifts in NMR and typically occur in
1.) Chiral molecules (not considered in this course)
2.) Rings
3.) Double Bonds

Question 2

more electronegative atoms have a () frequency

Answer 2

higher

Question 3

aldehyde and carboxylic acid chemical shift

Answer 3

9-12 region

Question 4

aromatic hydrogens

Answer 4

6.5 - 8 region

Question 5

hydrogens on alkene

Answer 5

4.5 - 6.5 region

Question 6

how do pi electrons shield protons

Answer 6

magnetic field is going in different directions

Question 7

what percentage of hydrogens are in an alpha and beta state

Answer 7

50% alpha
50% beta

Question 8

the alpha state is aligned with () and () in energy

Answer 8

magnetic field, lower

Question 9

the beta state is aligned () and () in energy

Answer 9

against the magnetic field, higher

Question 10

splitting when equivalent

Answer 10

(N+N+1)

Question 11

splitting when nonequivalent

Answer 11

(N+1)(N+1)

Question 12

what splitting pattern does a doublet of doublet result in

Answer 12

1:1:1:1

Question 13

aryl

Answer 13

H’s on benzene

Question 14

axial and equatorial hydrogens are chemically different - why do we only see 1 signal (as a singlet) for cyclohexane

Answer 14

chair conformer innerconversion

Question 15

wet sample

Answer 15

the exchangeable H appears as a singlet and it no longer splits adjacent H signals

Question 16

how many resonance structures does benzene have

Answer 16

2 equivalent

Question 17

how many sp2 hybridized carbons does benzene have

Answer 17

6

Question 18

what are the criteria for aromaticity

Answer 18

1.) cyclic
2.) planar
3.) continuous ring of p orbitals
4.) (4n+2) pi electrons –> odd number of electron pairs

Question 19

anytime you see an Sp3, what can can you automatically classify the molecule as

Answer 19

nonaromatic –> not continuous loops of p orbitals

Question 20

what hybridization is C+

Answer 20

sp2

Question 21

what do you use to rank pKa

Answer 21

conjugate base of molecules

Question 22

after 7 carbons in a ring, what happens to the shape

Answer 22

the ring often buckles and are no longer planar

Question 23

non-aromatic compounds

Answer 23

do not fit the criteria for aromaticity

Question 24

antiaromatic compounds

Answer 24

fit all the criteria for aromaticity except they have an even number of electron pairs

Question 25

steps for ranking pKa

Answer 25

1.) draw conjugate base
(as pKa increases, acidity decreases)
2.) look at aromaticity to determine acidity
Most: aromatic
Least: antiaromatic

Question 26

going downhill to lower energy is more/less feasable

Answer 26

more

Question 27

Al, B, C+

Answer 27

all sp2

Question 28

diene

Answer 28

recieves bond

Question 29

dienophile

Answer 29

give bond

Question 30

dine and dienophile combine to form what

Answer 30

2 new c-c bonds and a cyclohexane ring

Question 31

molecular orbitals in diels alder

Answer 31

HOMO of diene overlaps with LUMO of dienophile

Question 32

order of reactivity of diene molecules in a diels alder rxn

Answer 32

locked cis>trans>cis&trans>locked trans

Question 33

1-substituted dienes produce what major product

Answer 33

ortho

Question 34

2-substituted dienes produce what major product

Answer 34

para

Question 35

diels alder stereochemistry

Answer 35

the stereochemical relationship of groups is retained from reactant to product
ex: groups that are cis on the dienophile are cis in the product

Question 36

substitution with () on diene speed up the rate of reaction

Answer 36

EDG

Question 37

substitution with () on dienophile speed up rate of rxn

Answer 37

EWG