Interpretation:
The reason for the statement “The mass spectrum of 3-methylpentane has a peak of very low relative abundance at
Concept introduction:
Mass spectrometry involves formation of ions in a mass spectrometer followed by separation and detection of the ions according to mass and charge.
The mass spectrum is a graph with mass (
One of the highest value m/z may or may not represent the molecular ion, that is, the ion with the formula weight of the original compound. When present, the molecular ion is usually not the base peak because the ions from the original compound molecule tend to fragment, thereby resulting in the other m/z peaks in the spectrum.
Small peaks having m/z values 1 or 2 higher than the formula weight of the compound are because of 13C and other isotopes.
Molecular ions formed by EI mass spectrometry are high-energy species and these are called radical cations because it contains both an unshared electron and a positive charge. Fragmentation of molecular ion means that a complex molecule is broken into smaller molecules and these fragments can undergo more breaking and so on.
Cleavage of a single bond produces a cation and a radical. The cation can be detected using positive ion mass spectrometry and because the radical is not charged, it will be undetected.
Chain branching or cleavage of a single bond at branch points will occur such that the carbocation formed is more stable. In simple words, the stability of carbocation determines the fragmentation pattern.
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Organic Chemistry
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- Organic Chemistry: A Guided InquiryChemistryISBN:9780618974122Author:Andrei StraumanisPublisher:Cengage LearningOrganic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning