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Ch. 14 - Structural Identification 1: Infrared Spectroscopy and Mass Spectrometry
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Non è quello che usi tu?Cambia libro di testo
Capitolo 13, Problema 41

The base peak in Figure 14.51 has m/z 45. Suggest a molecular formula and a structure for this fragment.
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Understand that the base peak in a mass spectrum represents the most abundant ion, and its m/z value is crucial for deducing the structure of the fragment.
The m/z value of 45 suggests a fragment with a molecular weight of 45. Consider common organic fragments that could have this mass.
Calculate possible molecular formulas that sum to a molecular weight of 45. For example, consider C3H9N (molecular weight: 3*12 + 9*1 + 14 = 45) or C2H5O (molecular weight: 2*12 + 5*1 + 16 = 45).
Evaluate the chemical plausibility of each formula by considering typical fragmentation patterns in mass spectrometry. For instance, C2H5O could represent an ethoxy group, which is a common fragment.
Propose a structure for the fragment based on the plausible molecular formula. For example, if C2H5O is considered, the structure could be an ethoxy group (CH3CH2O).

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Mass Spectrometry

Mass spectrometry is an analytical technique used to measure the mass-to-charge ratio (m/z) of ions. It helps identify the composition of a sample by analyzing the mass of its fragments. The base peak represents the most abundant ion, providing clues about the structure of the molecule.
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Fragmentation Patterns

Fragmentation patterns in mass spectrometry refer to the way molecules break apart into smaller ions. Understanding these patterns is crucial for deducing the structure of the original molecule. The m/z value of a fragment can suggest possible molecular formulas and structural components.
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Common Splitting Patterns

Molecular Formula Determination

Determining a molecular formula involves calculating the possible combinations of atoms that match the observed m/z value. This requires knowledge of atomic masses and common molecular fragments. For m/z 45, potential fragments could include C3H9N or C2H5O, guiding the identification of the structure.
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