N
X
C
Hal
O
N
S
P Si
Natural
Products
Solvents
C
C
C
C C
C
8.9 Nitrogen Compounds
403
Piperidines
Fragmentation:
N
H
– H
.
N
+
N
H
+
N
H
+
H
N
H
+
– H
.
– C 2 H 4
N
H
CH 3
+
N CH 2 H 2 C N CH 3
+
H 3 C N
H
CH 2
H 2 N CH 2
+
+
– CH 3
– C 3 H 6
m/z 70 (14% )
m/z 43 (34% )
m/z 44 (43% )
m/z 30 (52% )
– C 2 H 4
m/z 85 (43% )
m/z 84 (100% )
+ .
+ .
.
.
.
.
ESI-MS/MS: Elimination of NH 3 (Δm 17), CH 3 NH 2 (Δm 31), and CH 3 CH 2 NH 2
(Δm 45) from [M+H] + .
Ion series: Even-mass fragments of the type C n H 2n N (m/z 42, 56, 70, 84, …) and
C n H 2n+2 N (m/z 30, 44, 58, …) as well as odd-mass fragments of the type C n H 2n+1 N
(m/z 43, 57, 71, 85, …).
Intensities: Intensive local maxima evenly distributed over the whole mass range if
no substituent is bonded to the C atom next to N. Otherwise, dominating maxima
by loss of such substituents.
Molecular ion: Significant or strong if no substituent is bonded to the C atom next
to N; otherwise, weak. Tendency to form [M-H] + .
Piperazines
Fragmentation: As for cyclic amines, enhanced primary ring cleavage at C–C
bonds next to the N atom.
ESI-MS/MS: Elimination of CH 2 =NH (Δm 29) and CH 3 CH=NH (Δm 43) from
[M+H] + .
Ion series: Even-mass fragments of the type C n H 2n N (m/z 42, 56, 70, 84, …) and
C n H 2n+2 N (m/z 30, 44, 58, …) as well as odd-mass series of the type C n H 2n+1 N
(m/z 43, 57, 71, 85, …).
Intensities: Intensive local maxima evenly distributed over the whole mass range if
no substituent is bonded to the C atom next to N. Otherwise, dominating maxima
by loss of such substituents.
Molecular ion: Significant or strong if no substituent is bonded to the C atom next
to N; otherwise, weak. Tendency to form [M-H] + .