Alkynes chemical ionization

Diphenylthiirene 1-oxide and several thiirene 1,1-dioxides show very weak molecular ions by electron impact mass spectrometry, but the molecular ions are much more abundant in chemical ionization mass spectrometry (75JHC21). The major fragmentation pathway is loss of sulfur monoxide or sulfur dioxide to give the alkynic ion. High resolution mass measurements identified minor fragment ions from 2,3-diphenylthiirene 1-oxide at mje 105 and 121 as PhCO" and PhCS, which are probably derived via rearrangement of the thiirene sulfoxide to monothiobenzil (Scheme 2). 

Mixtures of alkenes and alkynes can be analysed with detection limits in the nanogram range, by means of Fe(I) chemical ionization using tandem sector MS or GC-FTMS. The... 

A. Chemical Ionization of Alkynes with Metal Ions... 

An elegant method for locating the position of a triple bond of an alkyne is in situ derivatization in a chemical ionization source, followed by MS/MS of the adduct. The most successful approach has involved reaction of the alkyne with Fe(CO)x [from... 

The chemical ionization mass spectra of a number of alkenes and alkynes have been investigated using methane as reactant. The compounds studied comprised straight-chain 1-mono-olefins, branched and internal mono-olefins, and a number of compounds of diverse types (di- and tri-olefins, monocyclic and bicyclic mono-olefins, cyclic di-olefins, and acetylenes). 

Busker, E. Budzikiewicz, H. Studies in Chemical Ionization Mass Spectrometry. 2. Isobutane and Nitric Oxide Spectra of Alkynes. Org. Mass Spectrom. 1979,14, 222-226. 

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