Mass Spectrometric Behaviour of (Z)-2-Chloro-3(Dichloromethyl)-4-Oxobutenoic Acid and (Z)-2-Chloro-3(Chloromethyl)-4-Oxobutenoic Acid (Open Forms of MX and CMCF Respectively) Molecular Ions

2002 ◽  
Vol 8 (4) ◽  
pp. 299-303 ◽  
Author(s):  
Rafał Frański ◽  
Przemysław Andrzejewski ◽  
Jacek Nawrocki
Keyword(s):  
High Resolution ◽  
Chlorine Atom ◽  
Molecular Ions ◽  
Mass Spectrometric ◽  
Open Form ◽  
Chloromethyl Group ◽  
High Resolution Data ◽  
Fragmentation Pathways ◽  
Metastable Ions ◽  
Resolution Data

Fragmentation pathways of ( Z)-2-chloro-3(dichloromethyl)-4-oxobutenoic acid (MX open form) and ( Z)-2-chloro- 3(chloromethyl)-4-oxobutenoic acid (CMCF open form) are discussed on the basis of recorded metastable ions and high-resolution data. It was found that the presence of the additional chlorine atom in the chloromethyl group affects the fragmentation pathways of MX. The elimination of the dichloromethyl radical was observed for the MX+• ion but elimination of the chloromethyl radical does not occur for the CMCF+• ion. For the latter compound, elimination of a CO molecule was registered. The elimination of an HCl molecule occurs for both ions.

scholarly journals Zur McLafferty-Umlagerung bei Radikalkationen von Phenylpyridylalkanonen/ On the McLafferty Rearrangement of Ionized Phenyl Pyridyl Alkanones

1981 ◽  
Vol 36 (7) ◽  
pp. 865-877 ◽  
Author(s):  
Bernd Richter ◽  
Helmut Schwarz
Keyword(s):  
High Resolution ◽  
Hydrogen Transfer ◽  
Decisive Role ◽  
Molecular Ions ◽  
High Resolution Data ◽  
Mclafferty Rearrangement ◽  
Fragment Ions ◽  
Product Ions ◽  
Isomerization Processes ◽  
Resolution Data

Abstract A detailed investigation concerning the genesis of McLafferty rearrangement products from molecular ions of phenyl pyridyl alkanones reveals the following features: 1) The various products are not formed by competitive dissociations of the molecular ion. Most of the relevant fragment ions are generated from the primary McLafferty product of a hydrogen transfer to the ionized carbonyl group (M+·→m/z 163, ion k). The ion k plays a decisive role for the generation of the abundant product ions at m/z 93 (ion g) and m/z 106 (ion s) both of which are formed by further dissociation of k. Details of the mechanisms for the decomposition of k are obtained by investigating [D]-labelled isotopomers, the analysis of low and high resolution data, the application of MIKE and CA spectra. The problem of keto/enol tautomerism between some ions, relevant in this context, is discussed and it is shown that these isomerization processes are not involved. A detailed description is given for the syntheses of various [D]-labelled phenyl pyridyl alkanones.

The mass spectra of trifluoroacetyl-2,5-diketopiperazines. I. cyclo-(-Gly-X), cyclo-(-Ala-X) (X = Gly, Val, Leu, Ile), and cyclo-(-Ala-Ala)

1979 ◽  
Vol 57 (15) ◽  
pp. 2037-2051 ◽  
Author(s):  
George P. Slater ◽  
Lawrence R. Hogge
Keyword(s):  
Mass Spectrum ◽  
Mass Spectra ◽  
High Resolution Data ◽  
Fragmentation Pathways ◽  
Molecular Ion ◽  
Metastable Ions ◽  
Fragmentation Patterns ◽  
The Individual ◽  
Derivatives Of ◽  
Resolution Data

The trifluoroacetyl derivatives of the 2,5-diketopiperazines cyclo-(-Gly-X), cyclo-(-Ala-X) (X = Gly, Val, Leu, Ile), and cyclo-(-Ala-Ala) were examined by GC–MS. The molecular ion was readily detectable only for TFA-cyclo-(-Gly-Gly) (m/e 306, 9%). For those compounds containing a valyl or leucyl/isoleucyl residue the ion of highest mass in the spectrum was formed by elimination of C3H6 or C4H8, respectively, from the molecular ion. In the TFA-cyclo-(-Gly-X) series this ion corresponded to the molecular ion of TFA-cyclo-(Gly-Gly) (m/e 306), and in the TFA-cyclo-(-Ala-X) series, to the molecular ion of TFA-cyclo-(-Ala-Gly) (m/e 320). The fragmentation patterns proposed for these compounds are based on the further degradation of these parent ions so that each compound within a series has a similar mass spectrum. However, sufficient differences were detectable in the various spectra to permit identification of the individual DKP's.Many of the fragmentation pathways devised to explain the mass spectra were supported by high resolution data and appropriate metastable ions.

Using high resolution data to reveal depth-dependent mechanisms that drive land subsidence: The Venice coast, Italy

2009 ◽  
Vol 474 (1-2) ◽  
pp. 271-284 ◽  
Author(s):  
L. Tosi ◽  
P. Teatini ◽  
L. Carbognin ◽  
G. Brancolini
Keyword(s):  
High Resolution ◽  
Land Subsidence ◽  
High Resolution Data ◽  
Resolution Data

Estimating maize lethal necrosis (MLN) severity in Kenya using multispectral high-resolution data

2021 ◽  
Author(s):  
Kyalo Richard ◽  
Elfatih M. Abdel-Rahman ◽  
Sevgan Subramanian ◽  
Johnson O. Nyasani ◽  
Michael Thiel ◽  
...  
Keyword(s):  
High Resolution ◽  
High Resolution Data ◽  
Resolution Data

scholarly journals Separating Geophysical Signals Using GRACE and High‐Resolution Data: A Case Study in Antarctica

2018 ◽  
Vol 45 (22) ◽  
pp. 12,340-12,349 ◽  
Author(s):  
Olga Engels ◽  
Brian Gunter ◽  
Riccardo Riva ◽  
Roland Klees
Keyword(s):  
High Resolution ◽  
High Resolution Data ◽  
Resolution Data
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