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The effect of molecular geometry on the fragmentation of methyl esters of cyclobut‐3‐ene‐1,2‐dicarboxylic acids
Author(s) -
Weinstein S.,
GilAv E.,
Leftin J. H.,
Levy E. C.,
Mandelbaum A.
Publication year - 1974
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.1210090806
Subject(s) - chemistry , ene reaction , ion , cyclobutene , stereochemistry , deuterium , fragmentation (computing) , organic chemistry , medicinal chemistry , ring (chemistry) , physics , quantum mechanics , computer science , operating system
Elimination of CH 3 OH from the molecular ions of the methyl esters of cyclobut‐3‐ene‐1, 2‐dicarboxylic acids under electron‐impact occurs to a much greater extent in stereoisomers having a trans configuration than in the cis analogues. Deuterium labelling shows that this process takes place via different mechanisms in the stereoisomeric esters. The abundance ratio [M CH 3 OH] ˙+ /[M CH 3 O]+ is suggested as the most sensitive criterion for the deduction of configuration in this system. Determination of the geometry of the cyclobutene esters by n.m.r. spectroscopy as well as by pyrolysis to corresponding isomeric muconates is also discussed.