Analytical Chemistry and Spectroscopy
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
The electron impact mass spectra of methyl esters of chloro-, bromo-, dichloro-, bromochloro- and dibromo-2-butenoic acids (13 esters at all) have been investigated. Generally, the peaks due to the following fragments are abundant: M+·, [M — OCH3]+, [M — CH3OH]+·, [M — X]+, [M — OCH3 — CO]+ or [M — COOCH3]+, [M — X — CH3OH]+ or [M — OCH3 — HX]+, [M — OCH3 — CO — HX]+, [M — OCH3 — X — X]+ and [M — OCH3 — CO — X — X]+. Characteristic for the 2- and 4-halo isomers are the primary losses of a methyl radical and methanol, and for the 3-halo isomers the loss of X· from M+·. Disparities between the spectra of the E and Z isomers are shown, the effect of position of halogen substitution being much more pronounced, as reported previously with the halogenated propenoic acid esters.
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