Mass Spectroscopy, Example #4

Analysis: C11H12O 3 MW = 192.21 Help with Analysis
Mass Spectrum

Mass Spectrum

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C11H12O 3 MW = 192.21

From the molecular formula, the compound has "6 degrees of unsaturation" (six double bonds, carbonyls, rings, or any combination thereof). The large number of degrees of unsaturation strongly suggests the presence of an aormatic ring.

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The spectrum shows a small molecular ion peak, and a peak at m-45, suggesting the presence of an ethoxy group (-O-CH2CH3). The very minor peaks at 91 and 43 suggest that the molecule does not contain a benzyl unit or a methyl ketone. The base peak occurs at m/e = 105, and results from loss of a unit of m/e = 73, which is also observed. The molecular ion at 105 is characteristic of a carbonyl bonded directly to an aromatic ring.

Fragmentation of Common Functional Groups
Common Ions and Fragments

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Structure: structure

IUPAC Name: ethyl 3-oxy-3-phenylpropanoate (ethyl benzoylacetate)

MS Fragments:
fragments

The spectrum shows a small molecular ion peak, and a peak at m-45, suggesting the presence of an ethoxy group (-O-CH2CH3). The very minor peaks at 91 and 43 suggest that the molecule does not contain a benzyl unit or a methyl ketone. The base peak occurs at m/e = 105, and results from loss of a unit of m/e = 73, which is also observed. The molecular ion at 105 is characteristic of a carbonyl bonded directly to an aromatic ring.

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Copyright 1996, Paul R. Young, University of Illinois at Chicago, All Rights Reserved