ch 13

Question 1

The frequency at which a particular carbon atom appears in the ¹³C NMR spectrum is called the

Answer 1

chemical shift

Question 2

Answer 2

3

Question 3

Answer 3

5

Question 4

Answer 4

1

Question 5

An electronegative group attached to a carbon atom will ______ the electron density around the atom shifting the ¹³C NMR peak _______.

Answer 5

decrease; downfield

Question 6

Answer 6

III

Question 7

Answer 7

III

Question 8

An ethyl group (CH₃CH₂-) that is attached to a quaternary carbon has what splitting pattern in a NMR spectrum?

Answer 8

A triplet and a quartet with relative intensities of 3 and 2, respectively.

Question 9

Answer 9

IV

Question 10

Answer 10

IV

Question 11

“3 0” code

Answer 11

Question 12

“6 1” code

Answer 12

Question 13

“9 0” code

Answer 13

Question 14

3 2 or 2 3 cross

Answer 14

Question 15

Determine if hydrogens are homotopic, diastereotopic, enantiotropic, or unrelated

Answer 15

Type 1: Hydrogens are coming off same carbon
- replace 1 hyd with dutarium and count chiral centers
1. homotopic if ZERO chiral centers
2. enantiotropic if ONE chiral center
3. diastereotopic if TWO or MORE chiral centers
Type 2: Hydrogens are coming off different carbons
- unrelated UNLESS…
1. if HYDROGENS are symmetrical to each other then run Type 1

Question 16

DEPT-90 tells us about

Answer 16

CH groups

Question 17

+ DEPT-135 tells us about

Answer 17

CH and CH3

Question 18

• Dept-135 tells us about

Answer 18

CH2

Question 19

C=O has a chemical shift of about

Answer 19

220 - 160

Question 20

C=C has a chemical shift of about

Answer 20

150 - 110

Question 21

CH3 has a chemical shift of about

Answer 21

25 - 10

Question 22

CH2 has a chemical shift of about

Answer 22

50 - 25

Question 23

aromatics have a chemical shift of about

Answer 23

140 - 110