N
X
C
Hal
O
N
S
P Si
Natural
Products
Solvents
C
C
C
C C
C
8.10 Sulfur Compounds
413
Cyclic Sulfides
Fragmentation: Primary cleavage of the C–C bond next to S, followed by
rearrangements and elimination of CH 3
· (base peak for tetrahydrothiapyrane) and
C 2 H 5
· . In tetrahydrothiophene, [M-1] + is also significant. HS · , H 2 S, and C 2 H 4
elimination from M +· .
Ion series: Sulfur-containing aliphatic fragments with one degree of unsaturation,
C n H 2n-1 S (m/z 45, 59, 73, 87, 101, …), m/z 87 being of special dominance.
Intensities: Overall distribution of peaks maximizing in the low mass range due to
S-containing fragments, C n H 2n-1 S (m/z 45, 59, 73, 87, …).
Molecular ion: Very strong. Characteristic 34 S isotope peak at [M+2] +· and [frag+2]
for S-containing fragments (4.5% per S atom).
Aromatic Sulfides [2]
Fragmentation: Loss of CS (Δm 44) and of HS · (Δm 33) from M +· .
Ion series: HCS + (m/z 45) is characteristic besides the aromatic fragments, C n H n
and C n H n±1 (m/z 39, 51–53, 63–65, 75–77, …).
Intensities: Intensive peaks mainly in the higher mass range.
Molecular ion: Strong. Characteristic 34 S isotope peak at [M+2] +· (4.5% relative to
M +· per S atom) and [frag+2] for S-containing fragments.
Disulfides
Fragmentation: Loss of RSS · , leading to alkyl cations and alkene elimination to
give RSSH +· . Cleavage of the S–S bond with or without H rearrangements, leading
to RS + , [RS - H] +· , and [RS - 2H] + . Loss of one or two S with or without H atoms is a
common process in cyclic, unsaturated, and aromatic disulfides.
Ion series: In saturated aliphatic disulfides, H 2 S 2 and its alkyl homologues are
characteristic (m/z 66, 80, 94, …).
Intensities: Variable.
Molecular ion: Usually strong. Characteristic 34 S isotope peak at [M+2] +· and
[frag+2] for S-containing fragments (4.5% per S atom).