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Mass spectra of chlorinated esters: 2—Methyl mono‐ and dichlorobutanoates
Author(s) -
Korhonen Ilpo O. O.
Publication year - 1982
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.1210171105
Subject(s) - mass spectrum , chemistry , fragmentation (computing) , polyatomic ion , spectral line , ion , stereochemistry , metastability , medicinal chemistry , organic chemistry , physics , astronomy , computer science , operating system
The mass spectral fragmentations of methyl mono‐ and dichlorobutanates have been studied. Deutrium labelling and metastable ion analysis were used to elucidate the fragmentation mechanisms. The molecular ion peaks of the esters are weak and show only in the spectra of the monochloro isomers. A McLafferty rearrangement gives the base peaks in the spectra of methyl 2‐chloro‐, 4‐chloro‐ and 4,4‐dichlorobutanoate; α‐cleavage, [COOCH 3 ] + , in methyl 2,2‐ and 2,4‐dichlorobutanoate; [MCl] + , in methyl 3‐chlorobutanoate; [MClHCl] + , in methyl 3,4‐dichlorobutanoate; [MClCH 2 CO] + , in methyl 3,3‐dichlorobutanoate and [MClCOOCH 3 ] +˙ , in methyl erythro ‐ and threo ‐2,3‐dichlorobutanoate. The mass spectra of the stereoisomers are nearly identical, the loss of a chlorine atom and the McLafferty rearrangement giving the higher peaks in the spectrum of the threo form.