Concept explainers
Interpretation:
The formula of the ion responsible for the base peak is to be determined.
Concept introduction:
In a mass spectrometer, the molecules of the compound are bombarded with high energy electrons. This generally results in one electron from the molecule being knocked out. The resulting ion is a radical ion with an odd number of electrons, called the molecular ion. Since the mass of an electron is negligible, the mass of the molecule and the molecular ion are essentially the same.
The molecular ion is a high energy species and breaks up into a number of fragments, one of which carries the charge. Another source of fragmentation is the bombarding electrons themselves. These electrons often have energies sufficient to not just knock out an electron but also enough to break bonds.
The only species detected in the mass spectrometer are the charged species and their separation is based on the
The mass spectrum shows the distribution of the relative abundance of various ion fragments as a function of their
This means the
The most abundant ion, however, is not the molecular ion. In most cases, it is of a lower mass. The peak for this ion is called the base peak. The spectrum is scaled so that the base peak is 100% relative abundance.
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Organic Chemistry: Principles and Mechanisms (Second Edition)
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- Based on the spectra you located, does your molecule have a carbonyl? If so, what functional group is it a part of (carboxylic acid, ketone, aldehyde, ester, amide) and what is the frequency (in wavenumbers) of the absorption peak? If not, what is the approximate frequency range for a carbonyl? Does your molecule have either an –O-H or –N-H bond? If so, what functional group is it a part of (carboxylic acid, alcohol, amine, amide) and what is the frequency (in wavenumbers) of the absorption peak? If not, what are the approximate frequency ranges for an –O-H and an –N-H bond? Does your molecule have either an alkyne or nitrile functional group? If so, which functional group is it and what is the frequency (in wavenumbers) of the absorption peak? If not, what is the approximate frequency range for a triple bond?arrow_forwardMatch the compound to spectrum by drawing the structure next to correct spectrum. Then explain by describing the total number of signals each structure should have and which carbon would be farthest downfield.arrow_forwardOrder the following protons from lowest to highest chemical shift value.arrow_forward
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- Organic Chemistry: A Guided InquiryChemistryISBN:9780618974122Author:Andrei StraumanisPublisher:Cengage Learning