Regio- and Stereoselectivity in CE-CI

Example In epimeric 4-methylcyclohexanols the methyl and the hydroxyl group can either both reside in axial position (cis) or one is equatorial and the other axial (trans). In the trans isomer, stereospecific 1,4-H20 elimination should proceed easily (Chap. 6.10.3), while H2O loss from the cis isomer is more demanding. CE-CI using CgFe reactant ions clearly reveals the difference between these stereoisomers from the according lvr /[M-H20] ratio determined as trans cis = 0.09 2.0 = 23) [69]. 

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