Problem #3: The molecular formula for an unknown compound is C5H10O. Data for the 1H NMR, 13C NMR, infrared and mass spectra for this compound are available by clicking on the buttons below; use the "Return" button to return to this screen. Help with the interpretation of each spectrum is available and you can review background and selected correlation tables by clicking on the links in the MENU above. Using the spectral and analytical information provided, determine the structure for this compound.

 






















 

NMR Spectrum
Problem #3: C5H10O

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 Problem #3: C5H10O

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 Problem #3: C5H10O
13C NMR: quartet: 16.7 ppm quartet: 22.0 ppm doublet: 45.2 ppm singlet: 210.2 ppm

Problem #3: C5H10O

  • The molecule contains an oxygen, and from the analysis, contains one double bond, carbonyl or ring.
  • The mass spectrum displays a molecular ion and the base peak represents the formation of the acylium ion, indicating the presence of a methyl adjacent to a carbonyl.
  • The 13C spectrum contains 4 peaks, requiring that the molecule have some symmetry. The splitting indicates the presence of two types of methyl groups in the "simple" region, and a CH, deshielded slightly by an electronegative group. The singlet at d 210 is consistent with an aldehyde or ketone.
  • The proton NMR shows evidence for an isolated methyl group and an isopropyl group.
  • The IR is consistent with a simple saturated hydrocarbon containing a carbonyl (most likely a ketone since there is no evidence of the aldehyde CH stretch at 2800 cm-1).
  • The simplest structure which is consistent with all of these data would be a simple ketone bonded to a methyl and an isopropyl group.