Proton transfer via strained transition states in the elimination of alcohols from MH+ ions of stereoisomeric diethers and hydroxy esters upon chemical ionization and collision-induced dissociation

2001 ◽  
Vol 36 (4) ◽  
pp. 422-429 ◽  
Author(s):  
Chagit Denekamp ◽  
Asher Mandelbaum
Keyword(s):  
Proton Transfer ◽  
Chemical Ionization ◽  
Transition States ◽  
Collision Induced Dissociation ◽  
Hydroxy Esters

Structure and fragmentation of C5H11O+ ions formed by chemical ionization

1985 ◽  
Vol 63 (3) ◽  
pp. 609-618 ◽  
Author(s):  
John V. Headley ◽  
Alex. G. Harrison
Keyword(s):  
Proton Transfer ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Collision Induced Dissociation ◽  
Ionization Mass ◽  
Fragmentation Reaction ◽  
Isotopic Labelling ◽  
Precursor Structure ◽  
Reaction Channels

The proton transfer chemical ionization mass spectra of eleven C5H10O isomers have been obtained using H3+, N2H+, HCO+, and D3+ as reagent ions. The chemical ionization mass spectra in combination with isotopic labelling and metastable ion studies have made it possible to elucidate the major fragmentation reaction channels of the C5H11O+ ions formed and their dependence on precursor structure. From collision induced dissociation studies nine stable distinct C5H11O+ ion structures have been identified; protonated 3-methylbutanone and protonated 2,2-dimethylpropanal readily interconvert by a pinacolic – retro-pinacolic rearrangement.

scholarly journals Using collision-induced dissociation to constrain sensitivity of ammonia chemical ionization mass spectrometry (NH<sub>4</sub><sup>+</sup> CIMS) to oxygenated volatile organic compounds

2019 ◽  
Vol 12 (3) ◽  
pp. 1861-1870 ◽  
Author(s):  
Alexander Zaytsev ◽  
Martin Breitenlechner ◽  
Abigail R. Koss ◽  
Christopher Y. Lim ◽  
James C. Rowe ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Chemical Ionization Mass Spectrometry ◽  
Collision Induced Dissociation ◽  
Ionization Mass ◽  
Oxygenated Volatile Organic Compounds ◽  
Volatile Organic

Abstract. Chemical ionization mass spectrometry (CIMS) instruments routinely detect hundreds of oxidized organic compounds in the atmosphere. A major limitation of these instruments is the uncertainty in their sensitivity to many of the detected ions. We describe the development of a new high-resolution time-of-flight chemical ionization mass spectrometer that operates in one of two ionization modes: using either ammonium ion ligand-switching reactions such as for NH4+ CIMS or proton transfer reactions such as for proton-transfer-reaction mass spectrometer (PTR-MS). Switching between the modes can be done within 2 min. The NH4+ CIMS mode of the new instrument has sensitivities of up to 67 000 dcps ppbv−1 (duty-cycle-corrected ion counts per second per part per billion by volume) and detection limits between 1 and 60 pptv at 2σ for a 1 s integration time for numerous oxygenated volatile organic compounds. We present a mass spectrometric voltage scanning procedure based on collision-induced dissociation that allows us to determine the stability of ammonium-organic ions detected by the NH4+ CIMS instrument. Using this procedure, we can effectively constrain the sensitivity of the ammonia chemical ionization mass spectrometer to a wide range of detected oxidized volatile organic compounds for which no calibration standards exist. We demonstrate the application of this procedure by quantifying the composition of secondary organic aerosols in a series of laboratory experiments.

scholarly journals An Organic Chemist’s Guide to Electrospray Mass Spectrometric Structure Elucidation

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 611 ◽  
Author(s):  
Arnold Steckel ◽  
Gitta Schlosser
Keyword(s):  
Atmospheric Pressure ◽  
Structure Elucidation ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Atmospheric Pressure Chemical Ionization ◽  
Collision Induced Dissociation ◽  
Tandem Mass ◽  
Tandem Mass Spectra ◽  
Pressure Chemical Ionization ◽  
Pressure Chemical

Tandem mass spectrometry is an important tool for structure elucidation of natural and synthetic organic products. Fragmentation of odd electron ions (OE+) generated by electron ionization (EI) was extensively studied in the last few decades, however there are only a few systematic reviews available concerning the fragmentation of even-electron ions (EE+/EE−) produced by the currently most common ionization techniques, electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI). This review summarizes the most important features of tandem mass spectra generated by collision-induced dissociation fragmentation and presents didactic examples for the unexperienced users.

Understanding difficulties of irregular number-membered ring transition states for intramolecular proton transfer in excited state

Tetrahedron ◽  
2017 ◽  
Vol 73 (4) ◽  
pp. 403-410 ◽  
Author(s):  
Xiaozhuan Qin ◽  
Ge Ding ◽  
Zhenqiang Wang ◽  
Yulong Gong ◽  
Fang Gao ◽  
...  
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Transition States ◽  
Intramolecular Proton Transfer ◽  
Membered Ring
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