Concept explainers
In the mass spectrum of the following compounds, which is the tallest—the peak at m/z =57 or the peak at m/z = 71?
- a. 3·methylpentane
- b. 2·methylpentnne
Interpretation
The tallest peak should be identified.
Explanation of Solution
Mass fragmentation of 3-methyl pentane: In this molecule will be more adopted to lose an ethyl radical forming a secondary carbocation and a primary radical than a methyl radical forming secondary carbocation and methyl radical. In addition, 3-methylpentane ha undergoes for two path ways to lose an ethyl radical,
Therefore, the peak at
Mass fragmentation of 2-methyl pentane: The 2-methylpentane has undergoes for pathways to lose a methyl radical in each pathway and it cannot form a secondary carbocation by losing an ethyl radical. Loss of an ethyl radical would form a primary carbocation and a primary radical. Therefore, it will be more adopt to lose a methyl radical than an ethyl radical, the corresponding peak at
The 3-methyl pentane molecular peak at the m/e=71 has more intense then the peak at
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Chapter 14 Solutions
Organic Chemistry, Books A La Carte Edition (7th Edition)