Observation of diazonium ion - crown ether molecular complexes in the gas phase by field desorption and fast atom bombardment mass spectrometry (original) (raw)
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The detailed molecular composition of laboratory generated limonene ozonolysis secondary organic aerosol (SOA) was studied using ultrahigh-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Approximately 1200 molecular formulas were identified in the SOA over the mass range of 140 to 850 Da. Four characteristic groups of high relative abundance species were observed; they indicate an array of accretion products that retain a large fraction of the limonene skeleton. The identified molecular formulas of each of the groups are related to one another by CH 2 , O and CH 2 O homologous series. The CH 2 and O homologous series of the low molecular weight (MW) SOA (m/z < 300) are explained with a combination of functionalization and fragmentation of radical intermediates and reactive uptake of gas-phase carbonyls. They include isomerization and elimination reactions of Criegee radicals, reactions between alkyl peroxy radicals, and scission of alkoxy radicals resulting from the Criegee radicals. The presence of compounds with 10-15 carbon atoms in the first group (e.g. C 11 H 18 O 6) provides evidence for SOA formation by the reactive uptake of gas-phase carbonyls during limonene ozonolysis. The high MW compounds (m/z > 300) were found to constitute a significant number fraction of the identified SOA components. The formation of high MW compounds was evaluated by molecular formula trends, fragmentation analysis of select high MW compounds and a comprehensive reaction matrix including the identified low MW SOA, hydroperoxides and Criegee radicals as building blocks. Although the formation of high MW SOA may occur via a variety of radical and non-radical reaction channels, the combined approach indicates a greater importance of the non-condensation reactions over aldol and ester condensation reaction channels. Among these hemi-acetal reactions appear to be most dominant followed by hydroperoxide and Criegee reaction channels.
Journal of the American Chemical Society, 1992
Abtract: Nitrogen-and nitrous oxide-separated carbocationarboxylate ion pairs have been prepared by five different reactions: the rearrangement of N-nitroso amides, the reaction of acid chlorides with anti-diazoates, the reaction of acid chlorides with syn-diazoates, the reaction of acid chlorides with anions of N-nitroamines, and the decomposition of N-nitroso-0-acylhydroxylamines. Comparative stereochemical, I 8 0 scrambling, and product analyses have been made where common alkyl
Formation and stability of secondary ozonides from monoterpenes studied by mass spectrometry
Chemosphere, 2009
The secondary ozonide (SOZ) of limonene is a potential indoor pollutant from the gas-phase limonene/ ozone-reaction. A screening in the liquid phase was performed to investigate the yield and stability of SOZs from ten cyclic monoterpenes. They were cryo-ozonolyzed in pentane, and the reaction mixtures were analyzed with GC-MS with negative and positive chemical ionization and electron ionization. The investigated terpenes were: limonene, 4-carene, 3-carene, 2-carene, terpinolene, (+)-a-pinene, (À)b-pinene, isolimonene, sabinene and camphene. The only identified endo-SOZs were from: limonene, 3-carene, 4-carene and possibly isolimonene. Collision induced dissociation (CID) of the quasi-molecular-ions as a proxy measure of the stability of the pristine SOZs was investigated. LimoneneSOZ and 3-careneSOZ were found to be more stable than 4-careneSOZ and isolimoneneSOZ, which corresponded well to their relative yields. 3-careneSOZ was found to be a major product from the gas-phase ozonolysis.
Mass spectrometry of crown ethers
Journal of Inclusion Phenomena and Molecular Recognition in Chemistry, 1996
The mass spectra of benzo-15-crown-5 and benzo-l 8-crown-6 were investigated by mass spectrometry with different inlet systems, such as direct introduction, gas chromatography and liquid chromatography inlets. Different ionisation methods such as electron impact, chemical ionisation, electron capture or negative ion chemical ionisation were also studied. The results and the specific problems encountered for this group of substances are discussed based on the spectra obtained.
Mass spectrometry of diazo compounds
Mass Spectrometry Reviews, 1991
Since the publication of the first paper on the mass spectrometry of diazomethane in 1954, more than 50 publications dealing with diazoketones, diazoalkanes, diazonium salts, diazoesters, quinondiazides, diazoamides, diazoimines, diazosulfones, and organometallic diazo compounds have appeared. These compounds were studied by EI, CI, FAB, and other mass spectral techniques. Similarities between fragmentations in an ion source and thermolysis, photolysis, and acidcatalyzed reactions in solution have been reported. These observations have permitted results obtained from mass spectrometry to be used to predict the behavior of diazo compounds in solution. Diazo compounds have been used as models to aid the investigations of a range of reduction processes in an ion source using different ionization modes.
Pre-ionization effects in the mass spectrometry of some azoxybenzenes
Organic Mass Spectrometry, 1988
The mass spectrometry of azoxybenzene, and of several of its substituted variants, has been investigated under both electron ionization (EI) and chemical ionization (CI) conditions. The EI spectra largely confirm earlier mechanistic conclusions of Bowie et ui. (J. C k m . SOC. B, 621 (1%7)), but extend this work to consideration of the mechanism of formation of the [M -01'' ion. This unexpected ion has been shown, using techniques of tandem mass spectrometry, to arise from pre-ionization reduction to the corresponding azobenzene probably at the ion source surfaces. These pre-ionization effects cause the observed spectra to vary markedly with the conditions, including partial pressure of the sample, within the EI source. Under CI conditions (both methane and isobutane reagent gases) the pre-ionization reduction process is even more marked, and can involve reductive cleavage to the appropriate substituted anilines. Addition of water vapour favours the latter process over formation of [M -0 + HI+.