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Mass spectroscopic fragmentation pathways of 1,8‐nonadiyne
Author(s) -
Robbins Ronny Charles,
Foster Norman George
Publication year - 1985
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210200304
Subject(s) - fragmentation (computing) , triple bond , cleavage (geology) , chemistry , carbon chain , mass spectrum , bond cleavage , molecule , ionization , carbon fibers , crystallography , stereochemistry , mass spectrometry , ion , materials science , double bond , organic chemistry , catalysis , chromatography , fracture (geology) , composite number , computer science , operating system , composite material
Cleavage α to triple bonds in straight‐chain hydrocabons with only one triple bond is a very minor process. The mass spectrum of 1,8‐nonadiyne (mol. wt 120) shows strong peaks at around m / z 91, which points to a major fragmentation pathway of cleavage α to triple bonds in straight‐chain diynes. This study attempts to explain this paradox. Through‐space interaction was indicated through the use of carbon‐13 labelling of the terminal carbon atoms in 1,8‐nonadiyne, 1,2,8,9‐ 13 C‐1,8‐Nonadiyne and 3,7‐ 13 C‐1,8‐nonadiyne were prepared to determine which carbon atoms were lost in the process of [M] + ˙ and [M1] + going to m / z 91. These two molecules were chosen for ease of synthesis. Low‐resolution mass spectra and low‐voltage studies determined that a major portion of carbon atoms being lost were from the middle of the carbon chain. This points to a fragmentation pathway that results from through‐space interaction of the two terminal triple bonds. It is likely that ionization enhances this through‐space interaction of the two triple bonds.