Studies in organic mass spectrometry. VI [1]. Influence of alkylsubstituents on the fragmentation of 1,3‐dioxane

The mass spectra of 1,3‐dioxane and its 2,4,5‐ and 6‐alkyl substituted derivatives are discussed. Two main degradation patterns result respectively from initial elimination of a 2‐hydrogen atom or alkyl substituent and from the expulsion of a formaldehyde molecule. Subsequent fragmentations are highly influenced by the presence of substituents. 4,6‐Disubstituted 1,3‐dioxanes exhibit a distinct and typical fragmentation, starting with the expulsion of a substituent. Some of the mechanisms proposed are sustained by deuterium labeling.