NMR

Question 0

β (beta) spin

Answer 0

lines up “against the field” it is less stable and uses more energy

Question 1

α (alpha) spin

Answer 1

lines up “with the field” it is more stable and uses less energy

Question 2

What does the shielded/deshielded depend on?

Answer 2

The electronegativity of the element the H is attached to. Carbonyl’s (C=O are less electronegative than C-O).

Question 3

Number of signals

Answer 3

Shows how many different kinds of protons are present.

Question 4

Location of the signals

Answer 4

Shows how shielded or deshielded a proton is.

Question 5

Intensity of the signal

Answer 5

Shows the number of protons of that type.

Question 6

Signal splitting

Answer 6

Shows the number of protons on adjacent atoms.

Question 7

Chemical shift δ (ppm) =

Answer 7

Shift downfield from TMS (Hz) / spectrometer frequency (MHz)

Question 8

ΔE =

Answer 8

= hυ = γ(h/2π) Βο

Question 9

What causes the spin to flip from α to β?

Answer 9

When a proton interacts with a photon on the right energy.

Question 10

H (plank’s constant)

Answer 10

6.62x10^-34 J/sec

Question 11

Alkane (-CH3) shift

Answer 11

δ0.9

Question 12

Alkane (-CH2-) shift

Answer 12

δ1.3

Question 13

Alkane (-CH-) shift

Answer 13

δ1.4

Question 14

-C=O(CH3) shift

Answer 14

δ2.1

Question 15

-CΞC-H shift

Answer 15

δ2.5

Question 16

R-CH2-X (X=halogen or O) shift

Answer 16

δ3-δ4

Question 17

-C=C-H (vinyl) shift

Answer 17

δ5-δ6

Question 18

-C=C-CH3 (vinyl) shift

Answer 18

δ1.7

Question 19

Ph-H shift

Answer 19

δ7.2

Question 20

Ph-CH3 shift

Answer 20

δ2.3

Question 21

R-CHO shift

Answer 21

δ9-δ10

Question 22

R-COOH shift

Answer 22

δ10-δ12

Question 23

R-OH shift

Answer 23

δ2-δ5

Question 24

Ar-OH shift

Answer 24

δ4-δ7

Question 25

R-NH2 shift

Answer 25

δ1.5-δ4

Question 26

What causes the chemical shift to lower?

Answer 26

When the distance between the proton increases.

Question 27

More electronegative atoms…

Answer 27

Deshield more and give larger shift values

Question 28

Aromatic shift

Answer 28

δ7-δ8

Question 29

Vinyl shift

Answer 29

δ5-δ6

Question 30

Acetylenic shift

Answer 30

δ2.5

Question 31

Aldehyde shift

Answer 31

δ9-δ10

Question 32

N-H shift

Answer 32

δ3.5

Question 33

O-H shift

Answer 33

δ4.5

Question 34

Carboxylic acid shift

Answer 34

δ10+

Question 35

The are under each peak is…

Answer 35

Proportional to the number of protons

Question 36

Equivalent protons do NOT include…

Answer 36

Cis/trans isomers

Question 37

If a signal is spilt by N equivalent protons, then…

Answer 37

It is split into N+1 peaks

Question 38

Equivalent protons…

Answer 38

Do NOT split each other.

Question 39

Protons bonded to the same carbon will…

Answer 39

Split each other ONLY if they are NOT equivalent.

Question 40

In order to couple, protons must be separated by…

Answer 40

3 or less bonds!

Question 41

Peaks that split each other…

Answer 41

Point to each other.

Question 42

If you replace the protons on vinyl’s with a “Z”, and they form stereoisomers…

Answer 42

Then the protons are non-equivalent and WILL split each other.

Question 43

By adding H2O with deuterium to a compound that you suspect has an OH or NH group, you can determine that to be true by…

Answer 43

Deuterium has an even mass that won’t show up on NMR, but will when bonded to the groups.

Question 44

Off resonance decoupling

Answer 44

C nuclei is ONLY split by the protons attached. (N-1 protons= # of protons attached to the carbon)

Question 45

Proton spin decoupling

Answer 45

Adds noise to make protons go nuts to reveal a single unsplit signal.