2-Ethyl-2-methyl-1,3-dioxolane, mass

Acetals and ketals behave very similarly to ethers. However, fragmentation is even more favorable in acetals and ketals than in ethers, so the molecular ion peak of an acetal or ketal may be either extranely weak or totally absent. For example, in the mass spectrum of 2-ethyl-2-methyl-l,3-dioxolane (the ethylene ketal of methyl ethyl ketone), the molecular ion is not visible (Fig. 4.38). The highest mass peak is at miz = 101 from loss of a methyl radical via a-cleavage, and an alternative a-cleavage produces the large peak at miz = 87 formed by loss of an ethyl radical. The base peak in the spectrum is found at miz = 43, typical of 2-methyl-l,3-dioxolanes. 

The impurity present in the drug landiolol, an ultra-short-acting p-blocker, has been established by Stujber et al by the extensive use of NMR and mass spectroscopy as being [(45 )-2,2-dimethyl-l,3-dioxolan-4-yl]methyl 3- 4-[(25 )-2-hydro>y-3-(3- 4-[(25 )-2-hydroxy-3-[(2- [(morpholin-4-yl)carbonyl]amino ethyl)amino]propoxy]phenyl -JV-(2- [(morpholin-4-yl)-carbonyl]amino ethyl)propanamido)propoxy]phenyl propanoate. The authors have found that the compound exists in two rotameric forms at room temperature for both of them and C NMR data have been reported including proton-proton couplings across two and three bonds. 

The highest mass peak is at mh = 101 from loss of a methyl radical via a-cleavage, and an alternative a-cleavage produces the large peak at ndz = 87 formed by loss of an ethyl radical. The base peak in the spectrum is found at miz = 43, typical of 2-methyl-l,3-dioxolanes. 

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