Drug Metabolism in Drug Design and Development Basic Concepts and Practice

TABLE 12.3 (

Continued

)

Chemical shifts

Coupling constants

Integration

Relaxation times

>

d=(

nsample

nref

)/

nref

10

6

For a spectrometer

Heter-nuclear coupling 1 H



13

C

(^1) ,
H

15
N
,
1 H

19
F
(^13) ,
C
19
F
T^2
relaxation
d=
Dn
/spectrometer
frequency
10
6
Magnitude of
coupling constants
Integration is often used to
quantitate impurities orestimate the percentage ofresidual solvents
The scale goes from
0 ppm on left to higherppm on the right
1 H

1 H
, 1, 2, and 3
bonds

1Hzto20Hz
1 H
range 0 ppm to20 ppm
1 H

13
C
bond

140 Hz
Integral is not commonly
measured for carbons
Spin–lattice relaxation
13
C
range 0 ppm to
220 ppm
1 H

15
N
bond

90 Hz
T^2
relaxation times dependon the media of the molecule.
The magnitude of a
coupling-constantbetween two residuesin a particular moleculedoes not change withfield strength
Ratio of integral values
between residues in aparticular moleculedoes not change withfield strength
Solvent, viscosity, temperature
affects the line width.
The chemical shift value
of a residue in a particularmolecule does notchange at differentfield strengths
Short
T^2
value results in broader
peaks and Long
T^2
results in
narrower peaks
376