Problem #1: The molecular formula for an unknown compound is C3H8O. 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 #1: C3H8O 





















 
 Problem #1: C3H8O

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 Problem #1: C3H8O

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13C NMR:

quartet: 26.3 ppm

doublet:  64.9 ppm








     Problem #1:  C3H8O

 
     


     























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  • The molecule contains one oxygen, but from the analysis, contains no double bonds, rings, or carbonyls.

  • The mass spectrum displays no molecular ion, but does have an (m-1) peak, suggesting a labile hydrogen (-OH, -CHO, etc.).  The base peak is formed from loss of a methyl group.


  • The 13C spectrum contains 2 peaks, requiring that the molecule have some symmetry.  The splitting indicates the presence of a methyl group in the "simple" region, and a CH deshielded by an electronegative atom, such as an oxygen.


  • The proton NMR shows a septet and a doublet highly indicative of an isopropyl group.  The chemical shift of the isopropyl CH suggests it is adjacent to an electronegative atom.

  • The IR is consistent with a simple saturated alcohol.

  • The simplest structure which is consistent with all of these data would be a simple saturated alcohol having an isopropyl group.