scholarly journals Primary Amine Catalyzed Activation of Carbonyl Compounds: A Study on Reaction Pathways and Reactive Intermediates by Mass Spectrometry

Antonia Iazzetti ◽  
Giulia Mazzoccanti ◽  
Giorgio Bencivenni ◽  
Paolo Righi ◽  
Andrea Calcaterra ◽  
2012 ◽  
Vol 12 (1) ◽  
pp. 2167-2197
S. Kundu ◽  
R. Fisseha ◽  
A. L. Putman ◽  
T. A. Rahn ◽  
L. R. Mazzoleni

Abstract. The detailed molecular composition of secondary organic aerosols (SOA) from limonene ozonolysis was studied using ultrahigh-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. High molecular weight (MW) compounds (m/z > 300) were found to constitute a significant number fraction of the identified SOA components. Double bond equivalents (DBE = the number of rings plus the number of double bonds) increased with MW. The O:C ratios and relative abundances of compounds decreased with increasing MW. The mass spectra of limonene contain 4 distinct clusters of negative ions: Group I (140 < m/z < 300), Group II (300 < m/z < 500), Group III (500 < m/z < 700) and Group IV (700 < m/z < 850). A number of CH2 and O homologous series of low MW SOA (Group 1) with carbon number 7–15 and oxygen number 3–9 were observed. Their occurrence can be explained with isomerization and elimination reactions of Criegee radicals, reactions between alkyl peroxy radicals, and scission of alkoxy radicals resulting from the Criegee radicals. Additionally, fragmentation analysis and observations of formaldehyde homologous series provide evidence for aerosol growth by the reactive uptake of generated gas-phase carbonyls in limonene ozonolysis. The decreasing O:C ratios between group of compounds indicated the importance of condensation (aldol and esterification) reaction pathways for high MW compound formation. However, the prominent DBE changes of 2 between the groups of compounds and selected fragmentation (MS/MS) analysis of Group II and Group III ions indicated a predominance of non-condensation (hydroperoxide, Criegee and hemi-acetal) reaction pathways. A reaction matrix created with the combination of low MW SOA, hydroperoxides, and Criegee radicals indicated higher frequencies for the hemi-acetal and condensation reaction pathways. Overall, the combined approach confirms the importance of non-condensation reaction pathways over condensation reaction pathways. Among the non-condensation reaction pathways, hemi-acetal reactions appear to be most dominant followed by hydroperoxide and Criegee reactions.

2020 ◽  
pp. 174751982092308
Yanqin Wang ◽  
Biao Hu ◽  
Qiaohe Zhang ◽  
Siyun Zhao ◽  
Yuxuan Zhao ◽  

A fast and efficient Selectfluor-triggered fluorination/cyclization reaction of o-hydroxyarylenaminones has been successfully developed. The reaction successfully provides an expedient method for the synthesis of 3-fluoro-chromones promoted by potassium carbonate, which shows readily available starting materials and is easy to operate. In addition, a plausible mechanism of this tandem cyclization reaction was proposed where 4 H-chromen-4-one, 2-(dimethylamino)-3,3-difluorochroman-4-one, and 3,3-difluoro-2-hydroxychroman-4-one were not found to be the reactive intermediates. Moreover, these novel compounds have been obtained in moderate to good yields, and their structures have been confirmed by 1H NMR, 13C NMR, and high-resolution mass spectrometry.

Synthesis ◽  
2020 ◽  
Vol 52 (14) ◽  
pp. 2106-2110
Nicolas Philippe ◽  
Serge Pérard ◽  
Franck Le Strat ◽  
Jörg Blankenstein ◽  
Sébastien Roy

With a view to make conveniently labeled mass spectrometry standards available, a set of deuterated sphingomyelins were prepared by a new expedient, flexible, robust, scalable, and high-yielding synthetic scheme starting from 2-azido-3-O-benzoylsphingosine as the key intermediate. Unlike previously published procedures, this work emphasizes the benefit arising from the choice of the azido function as a masking group for the reactive primary amine during the troublesome, though crucial, phosphorylation step.

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