Deck 14: Nmr Spectroscopy

Question 1

How many ¹H NMR signals are expected for the following compound?

A) 3
B) 4
C) 5
D) 6
E) 8

Answer 1

5

Question 2

List the ¹H signals in order from highest to lowest chemical shift (frequency).

A) v, iv, iii, ii, i
B) i, ii, v, iv, iii
C) v, i, ii, iv, iii
D) v, ii, i, iii, iv
E) iv, iii, ii, i, v

Answer 2

v, i, ii, iv, iii

Question 3

Which of the following protons gives the highest frequency ¹H NMR signal?

A) 1
B) 2
C) 3
D) 4
E) 5

Answer 3

4

Question 4

Predict the splitting pattern for protons a, b, and c, giving that for
"a" first.
in order of protons a, b, c

A) doublet, doublet, singlet
B) multiplet, triplet, singlet
C) triplet, multiplet, triplet
D) triplet, triplet, singlet
E) all singlets

Question 5

Which of the following compounds will give the ¹H NMR spectrum shown below?

A) Br-CH₂CH₃
B) Cl-CH₂CH₂-Br
C) Br-CH(CH₃)₂
D) Cl₂CHCH₂-Br
E) HO-CH₂CH₃

Question 6

Predict the splitting pattern for protons a, b, and c, giving that for "a" first.

In order of protons a, b, c

A) singlet, doublet, singlet
B) doublet, triplet, doublet
C) triplet, multiplet, triplet
D) triplet, doublet of doublets, triplet
E) triplet, triplet, triplet

Question 7

Which of the following compounds best fits the ¹H NMR spectrum?

A)
B)
C)
D)
E)

Question 8

Which set of hydrogens are enantiotopic?
A

A) a and b
B) c and d
C) (a,b) and (c,c)
D) (a,c) and (b,d)
E) none of the above
B

C d
The methyl hydrogens a and b are identical (homotopic), whereas hydrogens c and d are enantiotopic.

Question 9

Predict the approximate region for the ¹³C chemical shifts for the alkene carbons of acrylic acid.
CH₂ ? CH-CO₂H

A) 200-150 ppm
B) 150-100 ppm
C) 100-50 ppm
D) 75-25 ppm
E) 50-0 ppm

Question 10

How many ¹³C signals are expected from this compound?

A) 5
B) 7
C) 8
D) 10
E) 11

Question 11

A DEPT ¹³C NMR spectrum is most useful for assigning signals to____________ groups.

A) CH₃
B) CH₂
C) CH
D) C
E) all of the above

Question 12

What type of NMR spectroscopy provides information about ¹H-¹H coupling?

A) COSY is ¹H-¹H shift-COrrelated SpectroscopY.
B) DEPT is used to distinguish between CH₃, CH₂, and CH groups.
C) HETCOR is used to reveal ¹³C-¹H shift correlations.
D) INADEQUATE is used to reveal ¹³C-¹³C shift correlations.
E) NOSEY locates protons that are close together in space.