Isopropylbenzene, mass spectrum

The formation of a substituted tropylium ion is typical for alkyl-substituted benzenes. In the mass spectrum of isopropylbenzene (Fig. 8.19), a strong peak appears at m/e - 105. This peak corresponds to loss of a methyl group to form a methyl-substituted tropylium ion. 

The formation of a substituted tropylium ion is typical for alkyl-substituted benzenes, hi the mass spectrum of isopropylbenzene (Fig. 4.24), a strong peak appears at miz = 105. This peak corresponds to loss of a methyl group to form a methyl-substituted tropyhum ion. The tropylium ion has characteristic fragmentations of its own. The tropylium ion can fragment to form the aromatic cyclopentadienyl cation (m/z = 65) plus ethyne (acetylene). The cyclopentadienyl cation in turn can fragment to form another equivalent of ethyne and the aromatic cyclopropenyl cation (m/z = 39) (Fig. 4.25). 

Mass spectrometry in this case is useless in specifying the relative positions of the two alkyl functions on the ring ortho, meta, or para). Isopropylbenzene gives a similar spectrum (see Equation 2.41). 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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