a
Table 3 Product ion studies using collisional activation (CA) and charge reversal (CR) spectra
Spectrum
[
CA: m/z(loss or formation)abundance]
Parent (m/z)
Product (m/z)
Mode
[CR: m/z(abundance)]
ؒ
ؒ
1
2
3
(115)
(115)
(115)
ϪH O (97)
CA
CR
96(H )100, 95(H )26, 82(CH )11, 79(H O)59, 67(CH O)68.
2
2
3
2
2
97(70), 96(100), 95(78), 81(56), 79(54), 77(34), 69(22), 67(78), 66(44), 65(50), 63(16), 57(4),
5(14), 53(33), 52(34), 51(38), 50(33), 43(8), 41(45), 39(53), 31(6), 29(14), 27(21), 26(16).
5
ؒ
ؒ
ϪH O (97)
CA
CR
96(H )100, 95(H )22, 82(CH )13, 79(H O)66, 67(CH O)70.
2
2 3 2 2
97(67), 96(100), 95(75), 81(49), 79(52), 77(38), 69(24), 67(84), 66(47), 65(54), 63(19), 57(4),
5(12), 53(29), 52(30), 51(29), 50(30), 43(6), 41(35), 39(46), 31(3), 29(12), 27(20), 26(15).
5
Ϫ
ϪH O (97)
CA
CR
95(H )24, 79(H O)100, 67(CH O)1, 41(C H )2.
2
2 2 2 3 5
97(21), 96(76), 95(100), 94(8), 81(52), 79(77), 77(45), 69(18), 67(45), 66(32), 65(28), 63(12),
7(4), 55(8), 53(12), 51(14), 41(21), 39(34), 31(4), 29(8), 27(15), 26(4).
5
ؒ
ؒ
CA
CR
96(H )100, 95(H )28, 82(CH )5, 79(H O)65, 67(CH O)52.
2 3 2 2
O–
O–
97(68), 96(100), 95(72), 81(52), 79(58), 77(39), 69(21), 67(83), 66(50), 65(55), 63(21), 57(4),
5(12), 53(31), 52(39), 51(32), 50(30), 43(6), 41(37), 39(46), 31(6), 29(12), 27(19), 26(12).
5
(
97)b
Ϫ
CA
CR
95(H )24, 79(H O)100, 67(CH O)1, 41(C H )1.
2
2
2
3
5
97(19), 96(70), 95(100), 94(8), 81(53), 79(66), 77(46), 69(18), 67(39), 66(29), 65(25), 63(11),
57(4), 55(8), 53(13), 51(15), 41(22), 39(37), 31(4), 29(6), 27(11), 26(4).
97)b
(
c
1
2
(115)
ϪCH O (85)
CA
CR
83(H )<20, 67(H O)60, 55(CH O)100.
2
2
2
2
85(4), 84(22), 83(12), 82(5), 81(2), 68(9), 67(60), 66(35), 65(36), 56(28), 55(85), 53(32),
1(26), 50(21), 43(6), 41(42), 39(100), 29(62), 28(16), 27(45), 26(20).
5
c
(115)
ϪCH O (85)
CA
CR
83(H )<20, 67(H O)68, 55(CH O)100.
2
2 2 2
85(6), 84(21), 83(13), 82(8), 81(4), 68(14), 67(62), 66(34), 65(38), 56(32), 55(87), 53(33),
1(28), 50(18), 43(8), 41(45), 39(100), 29(65), 28(18), 27(51), 26(20).
83(H )6, 67(H O)38, 55(CH O)100.
85(3), 84(9), 83(12), 82(6), 81(4), 70(5), 69(5), 67(7), 66(6), 65(5), 56(36), 55(100), 54(48),
53(46), 51(22), 50(22), 43(3), 41(24), 39(77), 29(52), 28(28), 27(42), 26(16).
5
OH
OH
CA
CR
2
2
2
–
85)d
(
CA
CR
67(H O)100, 55(CH O)1.
85(3), 84(83), 83(97), 82(5), 81(2), 70(1), 69(2), 68(15), 67(17), 66(10), 65(10), 57(2), 56(8),
55(29), 53(12), 51(9), 50(10), 43(6), 41(43), 39(100), 29(76), 28(26), 27(64), 26(18).
2
2
–
–
H
(
85)e
1
2
(115)
(115)
Ϫ(H O ϩ CH O) (67)
CR
CR
CR
67(100), 66(48), 65(34), 64(3), 63(6), 62(3), 61(2), 53(1), 52(4), 51(6), 50(5), 49(2), 41(7),
2
2
4
0(3), 39(10), 38(2), 37(1), 27(2), 26(1).
67(100), 66(50), 65(35), 64(2), 63(7), 62(3), 61(2), 53(1), 52(4), 51(6), 50(5), 49(2), 41(7),
0(2), 39(8), 38(2), 37(1), 27(2), 26(1).
Ϫ(H O ϩ CH O) (67)
2
2
4
67(100), 66(54), 65(36), 64(2), 63(7), 62(3), 61(2), 53(1), 52(4), 51(4), 50(3), 49(1), 41(6),
40(2), 39(7), 38(2), 37(1), 27(2), 26(1).
–
(
67)f
CR
67(100), 66(51), 65(39), 64(2), 63(7), 62(2), 61(1), 53(1), 52(5), 51(8), 50(7), 49(2), 41(22),
4
0(10), 39(39), 38(7), 37(4), 27(8), 26(3).
–
67)
g
(
3
(115)
ϪC H (59)
CR
CR
59(8), 58(29), 57(6), 56(8), 45(2), 44(4), 42(13), 41(15), 31(34), 30(48), 29(100), 28(32).
59(10), 58(28), 57(4), 56(12), 45(2), 44(6), 42(18), 41(19), 31(29), 30(43), 29(100), 28(34).
4
8
Ϫ
h
OCH CHO (59)
2
a
The abundances in both collisional activation and charge reversal spectra are dependent on both source conditions and the collision gas pressure.
b
As a general guide when comparing spectra, the abundance of an individual peak should be correct to ±10%. Formed by deprotonation of the
Ϫ
c
appropriate alcohol with HO . Weak spectrum: difficult to measure the abundance of the peak formed by loss of H because of baseline noise.
2
d
Ϫ
e
Ϫ
f
Formed by decarboxylation of HOCH CH CH᎐CHCH CO
. Formed by deprotonation of MeCH CH᎐CHCH OH with HO . Formed by
2 2
᎐
Ϫ h
2
2
᎐
2
2
Ϫ
g
deprotonation of penta-1,3-diene with HO . Formed by deprotonation of cyclopentene with HO . Reported by spectrum, see ref. 3.
The data considered to date show that 1 and 2 have iden-
tical fragmentations but do not indicate whether 1 cyclises to
We have not carried out labelling studies on the 3-oxepanol
anion 3: our primary interest in 3 was to determine whether its
fragmentations are different from those of 1 and 2. Even so,
the formation of m/z 59 (Scheme 2) is straightforward, while
the structure of m/z 97 is consistent with the fragmentation
pathway shown in Scheme 4.
2
before fragmentation occurs. This problem is resolved from
18
a consideration of the spectra (Table 4) of O labelled deriv-
atives (of 1 and 2). These spectra demonstrate the equilibration
of the two oxygens of 1 (and 2) prior to fragmentation: in the
case of 1, such equilibration requires rearrangement of 1 to 2
prior to fragmentation. The fragmentations of 2 have been
considered previously: it has been proposed that the oxygen
equilibration occurs by the proton transfer/ring opening equi-
Conclusions to Part A. 1. Ab initio and Arrhenius factor cal-
culations indicate that 1 should cyclise to both 2 and 3. The
barriers to transition states A and B are modest (computed as
14
Ϫ1
libria summarised in Scheme 3. Fragmentation of the ring
opened structures, particularly 4/5 and 6/7, account for both
the oxygen equilibration and the structures of the product
35.0 and 39.7 kJ mol respectively), and the Arrhenius factor
is larger for the formation of 2 than for 3. Thus 2 is predicted
to be the favoured product.
ions (Scheme 2) formed by the respective losses of H O and
2. Experimentally, 1 cyclises to give only 2 in the gas phase:
product 3 is not detected. It is proposed that the larger
2
CH O.
2
4
60
J. Chem. Soc., Perkin Trans. 2, 1999, 457–464