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Erschienen in:
2012 | OriginalPaper | Buchkapitel
6. Tables
verfasst von : Manfred Reichenbächer, Jürgen Popp
Erschienen in: Challenges in Molecular Structure Determination
Verlag: Springer Berlin Heidelberg
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Excerpt
Table 6.1
Table of natural isotopes of the important elements of organic compounds
|
X
|
X + 1
|
X + 2
|
||||
|---|---|---|---|---|---|---|
|
Element
|
m
|
%
|
m
|
%
|
m
|
%
|
|
H
|
1
|
100
|
2
|
0.015
|
||
|
C
|
12
|
100
|
13
|
1.1
|
||
|
N
|
14
|
100
|
15
|
0.37
|
||
|
O
|
16
|
100
|
17
|
0.04
|
18
|
0.20
|
|
F
|
19
|
100
|
||||
|
Si
|
28
|
100
|
29
|
5.1
|
30
|
3.35
|
|
P
|
31
|
100
|
||||
|
S
|
34
|
100
|
32
|
0.79
|
34
|
4.44
|
|
Cl
|
35
|
100
|
37
|
32.40
|
||
|
Br
|
79
|
100
|
81
|
97.94
|
||
Table 6.2
Normalized relative abundance of ions with chlorine and bromine atoms
|
X
|
X + 2
|
X + 4
|
X + 6
|
X + 8
|
X
|
X + 2
|
X + 4
|
X + 6
|
||
|---|---|---|---|---|---|---|---|---|---|---|
|
Cl
|
100
|
32
|
ClBr
|
77
|
100
|
25
|
||||
|
Cl2
|
100
|
64
|
10
|
Cl2Br
|
61
|
100
|
45
|
7
|
||
|
Cl3
|
100
|
96
|
31
|
3
|
ClBr2
|
44
|
1ßß
|
70
|
14
|
|
|
Cl4
|
78
|
100
|
48
|
10
|
0.8
|
|||||
|
Br
|
100
|
98
|
||||||||
|
Br2
|
51
|
100
|
49
|
|||||||
|
Br3
|
34
|
100
|
98
|
32
|
||||||
|
Br4
|
17
|
68
|
100
|
65
|
16
|
Table 6.3
Common fragments lost; [M-X] peaks
|
Mass X
|
Neutral molecules/radicals
|
Hints to
|
|---|---|---|
|
1
|
H
|
Unspecific; intense at Aryl–CHO
|
|
15
|
CH3
|
Intense if favorable for fragmentation
|
|
16
|
O
|
Aryl–NO2, N-oxide, Sulfoxide
|
|
NH2
|
Aryl–SO2NH2, R–CONH2
|
|
|
17
|
OH
|
O indicator, aryl–COOH
|
|
18
|
H2O
|
Alcohols, aldehyde, ketone
|
|
19
|
F
|
Fluorine compound
|
|
20
|
HF
|
Fluorine compound
|
|
26
|
C2H2
|
Aromatic hydrocarbons
|
|
27
|
HCN
|
Nitrile, N-heteroaromatic compounds
|
|
28
|
CO
|
Quinones, arylketones
|
|
C2H4
|
Arylethylether, -ester-, n-propylketones
|
|
|
29
|
CHO
|
Phenoles
|
|
C2H5
|
Ethylketones, n-propylketones
|
|
|
30
|
CH2O
|
Arylmethylethers
|
|
NO
|
Aryl–NO2
|
|
|
31
|
OCH3
|
Methylesters
|
|
32
|
HOCH3
|
o-Substituted arylmethylesters
|
|
32
|
S
|
S containing compounds
|
|
34
|
H2S
|
Thiols
|
|
36
|
HCl
|
Alkylchlorides
|
|
41
|
C3H5
|
Propylesters
|
|
42
|
CH2CO
|
Arylacetates, aryl–NHCOCH3, R–C(O)CH3
|
|
C3H6
|
Butylketones, aryl–O–propyl, aryl–n–butyl
|
|
|
43
|
C3H7
|
Propylketones, aryl–n–propyl compounds
|
|
CH3CO
|
Methylketones
|
|
|
44
|
CO2
|
Lactones, anhydrides, esters
|
|
45
|
COOH
|
Carboxylic acids
|
|
OC2H5
|
Ethylesters
|
|
|
46
|
HOC2H5
|
Ethylesters
|
|
46
|
NO2
|
Aryl–NO2
|
|
48
|
SO
|
Aryl–S=O
|
|
55
|
C4H7
|
Butylesters
|
|
56
|
C4H8
|
Arylpentyl, aryl–O–butyl, pentylketones
|
|
57
|
C4H9
|
Butylketones
|
|
C2H5CO
|
Ethylketone
|
|
|
60
|
CH3COOH
|
Acetates
|
|
61
|
CH3CH2S
|
Thiols, thioethers
|
|
64
|
SO2
|
Sulfonic acids and derivatives
|
Table 6.4
Common fragment ions
|
m/z
|
Possible ion
|
Hint to
|
|---|---|---|
|
19
|
F+
|
Fluorine compounds
|
|
29
|
CHO+
|
Aldehydes
|
|
C2H 5 +
|
Ethyl compounds
|
|
|
30
|
NO+
|
Nitro compounds
|
|
CH2 = NH 2 +
|
Amines
|
|
|
31
|
CH2 = OH+
|
Alcohols
|
|
33
|
HS+
|
Thiols
|
|
CH2F+
|
Fluorine compounds
|
|
|
39
|
C3H 3 +
|
Aromatic compounds
|
|
43
|
C3H 7 +
|
Alkyl groups
|
|
CH3CO+
|
Acetyl compounds
|
|
|
44
|
CO 2 +
|
Carboxylic acids
|
|
CH2CH–OH+
|
Aldehydes (McLafferty rearrangement)
|
|
|
C2H6N+
|
Amines
|
|
|
NH2C = O+
|
Amides
|
|
|
45
|
CHS+
|
Thiols, thioethers
|
|
COOH+
|
Carboxylic acids
|
|
|
CH3CHOH+
|
Alcohols
|
|
|
CH3–O = CH 2 +
|
Methylethers
|
|
|
46
|
NO 2 +
|
Nitro compounds
|
|
CH2S+
|
Thiols, thioethers
|
|
|
47
|
CH2SH+
|
Thiols, thioether
|
|
49/51
|
CH2Cl+
|
Alkylchloride
|
|
51
|
CHF 2 +
|
Fluorine compounds
|
|
C4H 3 +
|
Aromatic compounds
|
|
|
53
|
C4H 5 +
|
Aromatic compounds
|
|
55
|
C4H 7 +
|
Aromatic compounds
|
|
CH2 = CH–C ≡ O+
|
Cycloalkanones
|
|
|
57
|
C4H 9 +
|
Alkyl groups
|
|
C2H5C = O+
|
Ethylketones, Propionic acid esters
|
|
|
CH2 = CH–CH = OH+
|
Cycloalkanoles
|
|
|
58
|
CH2 = C(OH)CH 3 +
|
Alkanones
|
|
(CH3)2 N = CH 2 + ,
|
||
|
C2H5NH = CH 2 +
|
Amines
|
|
|
59
|
CH2 = C(OH)NH 2 +
|
Amides
|
|
CH3COO+
|
Methylesters
|
|
|
CH3C(CH3) = OH+
|
Alcohols, esters
|
|
|
60
|
CH2COOH+
|
Carboxylic acid with a γ-H
|
|
61
|
C2H5S+, CH3SCH 2 +
|
Thiols
|
|
65
|
C5H 5 +
|
Aromatic compounds (benzylic compounds)
|
|
66
|
H2S 2 +
|
RS–SR
|
|
69
|
CF 3 +
|
Trifluormethyl compounds
|
|
C5H 9 +
|
Alkenes, cycloalkanes
|
|
|
70
|
C5H 10 +
|
Alkenes
|
|
71
|
C5H 11 +
|
Alkyl groups
|
|
C3H7C = O+
|
Butyric acid esters, propylketones
|
|
|
72
|
C3H7CHNH 2 +
|
Amines
|
|
C2H5C(OH) = CH 2 +
|
Ethylketones
|
|
|
73
|
(CH3)3Si+
|
Trimethylsilyl compounds
|
|
74
|
CH2–C(OH)OCH 3 +
|
Methylesters
|
|
77
|
C6H 5 +
|
Aromatic compounds
|
|
79/81
|
Br+
|
Bromine compounds
|
|
80
|
C5H6N+
|
Pyrrol compounds
|
|
80/82
|
HBr+
|
Bromine compounds
|
|
81
|
C5H5O+
|
|
|
83
|
C4H3S+
|
|
|
85
|
C6H 13 +
|
Alkyl groups
|
|
C4H9C = O+
|
Butylketones
|
|
|
C5H9O+
|
Tetrahydropyranes
|
|
|
91
|
C7H 7 +
|
Benzyl compounds
|
|
91/93
|
C4H8Cl+
|
Alkylchlorides
|
|
92
|
C6H6N+
|
Alkylpyridines
|
|
93
|
C6H5O+
|
Phenolethers
|
|
93/95
|
CH2Br+
|
Alkylbromides
|
|
94
|
C6H5O+ + H
|
Phenol derivates
|
|
95
|
C5H3O 2 +
|
|
|
97
|
C5H5S+
|
|
|
99
|
C7H 15 +
|
Alkyl compounds
|
|
C5H8O 2 +
|
Ketales
|
|
|
105
|
C6H5C = O+
|
Benzoyl compounds
|
|
C6H5–CH2CH 2 +
|
Alkylbenzenes
|
|
|
106
|
C6H5NHCH 2 +
|
Alkylanilines
|
|
107
|
C7H7O+
|
Alkylphenoles
|
|
121
|
C8H 9 +
|
Alkylphenoles
|
|
149
|
C8H5O 3 +
|
Phthalic acid esters
|
Table 6.6
Important information from mass spectra of organic classes of compounds
|
Compound class
|
Information
|
|---|---|
|
Hydrocarbons
|
|
|
Saturated
|
M•+: mean intensity, but very weak at branched chain
|
|
Ion series: CnH2n+1; weaker: CnH2n and CnH2n−1
|
|
|
Maximum intensity at C3/C4, decreasing in a smooth curve
|
|
|
Branched chains show “unsteadiness” of the intensity curve
|
|
|
Alkenes
|
M•+: mean intensity
|
|
Ion series: CnH2n−1; weaker CnH2n and CnH2n+1
|
|
|
No recognition of the position of the double bond because of its migration
|
|
|
Cyclic alkenes: RDA fragmentations
|
|
|
Aromatic compounds
|
M•+: (very) intense
|
|
Characteristic ions: m/z = 39, 51, 65, 78, 79, 91
|
|
|
Monosubstitution: m/z = 77
|
|
|
Typical ion series: CnH n±1 +
|
|
|
Acetylides
|
M•+: frequently weak, [M-1] is more intense
|
|
Hydroxy compounds
|
|
|
Alcohols
|
M•+: weak at primary, very weak at secondary, not visible at tertiary alcohols; intense [M-1] peak
|
|
Primary alcohols: intense [M-2] and [M-3] peaks are also visible
|
|
|
α cleavage: intense m/z = 31 peak
|
|
|
Lost of H2O + CnH2n gives rise to ions [M-46], [M-74], etc.
|
|
|
Mass spectra of long-chain alcohols are similar to that of alkenes
|
|
|
Secondary, tertiary alcohols: m/z = 45, 59, etc.
|
|
|
α cleavage: m/z = 45, 59 etc.; m/z = 31 is only weak
|
|
|
M•+: weak, but always present
|
|
|
Alicyclic alcohols
|
Fragmentations: primary ring cleavage at the OH-bearing carbon atom, loss of H• gives rise to CnH2n−1O+ ions
|
|
Ion series: CnH 2n−1 + and CnH 2n−3 +
|
|
|
Phenoles
|
M•+: high intensity; [M-1] peak is also visible
|
|
Loss of CO (m/z = 28) and CHO (m/z = 29) after rearrangement
|
|
|
Ethers
|
|
|
Aliphatic
|
M•+: weak
|
|
Fragmentations:
|
|
|
1. α cleavage, followed by a McLafferty rearrangement
|
|
|
2. Cleavage of the C–O bond followed by charge-induced cleavage to alkylcations CnH 2n+1 +
|
|
|
Aromatic
|
M•+: intense
|
|
Fragmentations: primary cleavage of the ArO–R bond followed by CO elimination to arylcations
|
|
|
Loss of alkenes by McLafferty rearrangement (alkyl-C ≥ 2)
|
|
|
Diarylethers: [M-H], [M-CO], [M-CHO]
|
|
|
Aldehydes
|
|
|
Aliphatic
|
M•+: present
|
|
Fragmentations: [M-1] peak; m/z = 29 (CHO+ or C2H 5 + ) in long chain (>C4); in long chains CnH 2n+1 + peaks dominate
|
|
|
McLafferty rearrangement for ≥ C4 compounds
|
|
|
Unbranched: [M-18], [M-28], [M-43], [M-44]
|
|
|
Aromatic
|
M•+: very intense
|
|
α cleavage: [M-1] peak followed by CO elimination and C2H2 lost from the arylcations
|
|
|
Ketones
|
|
|
Aliphatic
|
M•+: mean intensity
|
|
Fragmentations: α cleavage followed by CO loss
|
|
|
McLafferty rearrangement: elimination of alkenes
|
|
|
Alkylcations dominate at long-chain ketones
|
|
|
Cyclic: intense molecular peak
|
|
|
Fragmentation: α cleavage after ring opening, loss of CO and alkyl radicals to stable ions
|
|
|
Aromatic
|
M•+: high intensity
|
|
Fragmentation: Aryl-C ≡ O+ by α cleavage
|
|
|
Carboxylic acids
|
|
|
Aliphatic
|
M•+: unbranched mono-carboxylic: weak; also [M + H]+
|
|
Fragmentation: short chain: α cleavage; [M-17], [M-45]
|
|
|
Long chain: ion series: CnH2n−1O 2 + , CnH 2n±1 +
|
|
|
McLafferty rearrangement (n C ≥ 4): m/z = 60 (base peak!)
|
|
|
Aromatic
|
M•+: intense
|
|
Fragmentation: α cleavage [M-17] (OH), [M-45] (CO2H)
|
|
|
Loss of CO2 (Δm = 44)
|
|
|
Ortho-effect: [M-H2O]
|
|
|
Carboxylic acid derivatives
|
|
|
Aliphatic esters
|
M•+: visible
|
|
R–C(O) –O–R′
|
Fragmentation: Recognition of the alcoholic and α substituent by McLafferty rearrangement
|
|
α cleavage: C(O)–OR′+, R–C(O)+
|
|
|
Intense R+ in short chain, but weak in long chain
|
|
|
Long-chain acid part: Ion series like carboxylic acids
|
|
|
Long-chain alcoholic part: Loss of CH3COOH and alkenes to R–C(OH) 2 + ions (m/z = 61, 75, etc.)
|
|
|
Benzyl-, phenyl-, heterocyclic acetates eliminate ketene ⇒ [M-42] peak
|
|
|
Aromatic esters
|
M•+: intense, but the intensity decreases with the chain length rapidly
|
|
Aryl–COOR
|
Fragmentation: α cleavage to [M-OR], [M-COOR]
|
|
R ≥ C2: McLafferty rearrangement with elimination of CH2 = CH2–R•′, ⇒ R+ ion series
|
|
|
Ortho-effect: Loss of ROH
|
|
|
Amides
|
M•+: present
|
|
R–CONH2
|
Fragmentation: McLafferty rearrangement (base peak!)
|
|
R–COONHR′
|
Primary: α cleavage: CONH 2 + (m/z = 44)
|
|
R–COONR′R″
|
Secondary, tertiary: McLafferty rearrangement if a γ-H is present
|
|
Aryl–COONRR′
|
Aryl–CONRR′: α cleavage dominates
|
|
N-compounds
|
|
|
Amines
|
M•+: very weak to invisible; [M-1] mostly present
|
|
Aliphatic
|
Fragmentations: α cleavage dominates
|
|
Secondary, tertiary: Loss of the largest α group
|
|
|
Primary: Ion series m/z = 30, 44, etc., CnH2n±1, CnH2n
|
|
|
Cycloalkylamines
|
M•+: present
|
|
Alkyl cleavage followed by primary ring opening at the N-containing carbon atom
|
|
|
Aromatic
|
Ion series: CnH2n
|
|
Aryl–NH2: Loss of N as HCN (m/z = 27)
|
|
|
Alkyl-C ≡ N
|
M•+: very weak or not present; [M-1] frequently strong
|
|
Fragmentations: McLafferty rearrangement: m/z = 41 (base peak!) ≥ C8 and higher: m/z = 97 (very intense)
|
|
|
Ion series: (CH2)nC ≡ N+ (m/z = 40, 54, etc.)
|
|
|
Aryl–NO2
|
M•+: very intense
|
|
Fragmentations: [M-46] (NO 2 • ), followed by loss of C2H2 ⇒ [M-72]
|
|
|
After rearrangement: [M-30] (NO), followed by loss of CO ⇒ M-58
|
|
|
NO+ ion (m/z = 30)
|
|
|
Halogen compounds
|
Intense [M + 2n]+ peaks: Cl and/or Br (see halogen patterns)
|
|
Unusual mass differences: Δm: 19(F); 20(HF); 127(I); 128(HI)
|
|
|
Aliphatic
|
M•+: Decreasing with increasing molecular mass, branching and number of halogen atoms
|
|
Fragmentations: Loss of halogen radicals
|
|
|
Cn with n > 6: Very intense C4H8X+ peak with X = Cl, Br
|
|
|
Aromatic
|
M•+: Mean intensity
|
|
Fragmentations: Lost of halogen radicals
|
|
|
S-compounds
|
[M + 2] peak: Recognition of S and determination of the S number
|
|
Thiols, thioethers
|
M•+: Mean intensity
|
|
Fragmentations: Loss of SH·(Δm = 33); H2S (Δm = 34)
|
|
|
Fragment ions: CH2SH+ (m/z = 47), CS•+ (m/z = 44), CHS+ (m/z = 45)
|
|
|
Sulfonic acids, esters
|
Loss of SO (Δm = 48), SO2 (Δm = 64)
|