N
X
C
O
N
S
Hal
Solvents
Natural
Products
P Si
C
C
C C
C
C
416
8 Mass Spectrometry
Cyclic Sulfones [4]
Fragmentation: Dominant elimination of SO 2 (Δm 64, followed by loss of CH 3
· ),
HSO 2
· (Δm 65, followed by loss of C 2 H 4 ), or CH 2 SO 2 (Δm 78). Weak signal at
[M-17] + due to OH · elimination.
Ion series: Mainly unsaturated hydrocarbon fragments, C n H 2n-1 (m/z 27, 41, 55, …).
Intensities: Intensive peaks in the lower mass range.
Molecular ion: Moderate. Characteristic 34 S isotope peak at [M+2] +· and [frag+2]
for S-containing fragments (4.5% per S atom).
Alkyl Aryl Sulfones [4]
Fragmentation: Isomerization of M +· to ar–OS(=O)alk and formation of the
phenoxy ion or the phenol radical cation with H rearrangement. The migration
of the aryl group depends on the type of substituents. It is facilitated by electron
donators and hindered by acceptors. Mainly in substituted or unsaturated alkyl
derivatives also isomerization to ar–S(=O)O–alk(ene) and formation of ar–S=O +
(m/z 125 if ar is phenyl). Single and double H rearrangements to give ar–S(=O)
OH +· and ar–S(OH) 2
+ . The probability of the double H rearrangement increases
with increasing chain length. In some derivatives, SO 2 elimination from M +·
dominates. Substituents X of the alkyl group may migrate to the aryl group to yield
X–ar–S=O + ions.
Ion series: Aromatic hydrocarbon fragments, C n H n and C n H n±1 (m/z 39, 51–53,
63–65, 75–77, ...), as well as S- and O-containing aromatic fragments at higher
masses.
Intensities: Intensive peaks mainly in the higher mass range.
Molecular ion: Strong. Characteristic 34 S isotope peak at [M+2] +· and [frag+2] for
S-containing fragments (4.5% per S atom).
Diaryl Sulfones [4,5]
Fragmentation: Predominant aromatic fragments of the type ar–O + and ar–SO +
(m/z 125 if ar is phenyl), formed after migration of one of the aryl groups. The
ar–SO 2
+ ion is unimportant; ar + is intensive. Small signals due to SO 2 , SO 2 H · , and
SO 2 H 2 eliminations (Δm 64, 65, and 66, respectively). With alkyl substituents in
ortho position, [M - OH] + and [M - H 2 O] +· are formed, upon which SO elimination
follows.
Ion series: Aromatic fragments, C n H n and C n H n±1 (m/z 39, 51–53, 63–65, 75–
77, …) and the S- and O-containing aromatic fragments at higher masses. Usually,
ar–SO + (m/z 125 if ar is phenyl) is very strong.
Intensities: Intensive peaks mainly in the higher mass range.
Molecular ion: Strong. Characteristic 34 S isotope peak at [M+2] +· and [frag+2] for
S-containing fragments (4.5% per S atom).
X
C
O
N
S
Hal
Solvents
Natural
Products
P Si
C
C
C C
C
C
416
8 Mass Spectrometry
Cyclic Sulfones [4]
Fragmentation: Dominant elimination of SO 2 (Δm 64, followed by loss of CH 3
· ),
HSO 2
· (Δm 65, followed by loss of C 2 H 4 ), or CH 2 SO 2 (Δm 78). Weak signal at
[M-17] + due to OH · elimination.
Ion series: Mainly unsaturated hydrocarbon fragments, C n H 2n-1 (m/z 27, 41, 55, …).
Intensities: Intensive peaks in the lower mass range.
Molecular ion: Moderate. Characteristic 34 S isotope peak at [M+2] +· and [frag+2]
for S-containing fragments (4.5% per S atom).
Alkyl Aryl Sulfones [4]
Fragmentation: Isomerization of M +· to ar–OS(=O)alk and formation of the
phenoxy ion or the phenol radical cation with H rearrangement. The migration
of the aryl group depends on the type of substituents. It is facilitated by electron
donators and hindered by acceptors. Mainly in substituted or unsaturated alkyl
derivatives also isomerization to ar–S(=O)O–alk(ene) and formation of ar–S=O +
(m/z 125 if ar is phenyl). Single and double H rearrangements to give ar–S(=O)
OH +· and ar–S(OH) 2
+ . The probability of the double H rearrangement increases
with increasing chain length. In some derivatives, SO 2 elimination from M +·
dominates. Substituents X of the alkyl group may migrate to the aryl group to yield
X–ar–S=O + ions.
Ion series: Aromatic hydrocarbon fragments, C n H n and C n H n±1 (m/z 39, 51–53,
63–65, 75–77, ...), as well as S- and O-containing aromatic fragments at higher
masses.
Intensities: Intensive peaks mainly in the higher mass range.
Molecular ion: Strong. Characteristic 34 S isotope peak at [M+2] +· and [frag+2] for
S-containing fragments (4.5% per S atom).
Diaryl Sulfones [4,5]
Fragmentation: Predominant aromatic fragments of the type ar–O + and ar–SO +
(m/z 125 if ar is phenyl), formed after migration of one of the aryl groups. The
ar–SO 2
+ ion is unimportant; ar + is intensive. Small signals due to SO 2 , SO 2 H · , and
SO 2 H 2 eliminations (Δm 64, 65, and 66, respectively). With alkyl substituents in
ortho position, [M - OH] + and [M - H 2 O] +· are formed, upon which SO elimination
follows.
Ion series: Aromatic fragments, C n H n and C n H n±1 (m/z 39, 51–53, 63–65, 75–
77, …) and the S- and O-containing aromatic fragments at higher masses. Usually,
ar–SO + (m/z 125 if ar is phenyl) is very strong.
Intensities: Intensive peaks mainly in the higher mass range.
Molecular ion: Strong. Characteristic 34 S isotope peak at [M+2] +· and [frag+2] for
S-containing fragments (4.5% per S atom).