LOW-ENERGY, LOW-TEMPERATURE MASS-SPECTRA .13. THE ALKYNES

The low energy, low temperature mass spectra of a number of linear alk-1-ynes (ethyne to octyne) are reported and discussed, where possible, in terms of ion thermochemistry. The spectra of hex-3-yne and hept-3-yne, together with those of the four linear octynes, are also discussed. The concept of fractional fragmentation is employed to distinguish between the four linear octynes. Branched alkynes are represented by 3,3-dimethylbut-1-yne and 2,2,5,5-tetramethylhex-3-yne, together with its isomer 2,3,4,5-tetramethylhexa-2,4-diene. Major ions in all spectra are [m-alkyl]+ and [M-olefin]+ and it is suggested that these are cyclic.