Problem #2: The molecular formula for an unknown compound is C6H12. 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 #2: C6H12

*
 Problem #2: C6H12

*
 Problem #2: C6H12
13C NMR: quartet: 30.6 ppm singlet: 45.2 ppm triplet: 108.5 ppm doublet: 149.3 ppm

Problem #2: C6H12

  • The molecule contains no heteroatoms, and from the analysis, contains one double bond or ring.
  • The mass spectrum displays a molecular ion and the base peak is formed from loss of a methyl group.
  • The 13C spectrum contains 4 peaks, requiring that the molecule have some symmetry. The splitting indicates the presence of a methyl group in the "simple" region, and a quaternary carbon, deshielded slightly by an electronegative group. The doublet and triplet are consistent with a terminal alkene.
  • The proton NMR shows three equivalent methyl groups, consistent with a tert-butyl group. The multiplets in the region 5 - 6 ppm are consistent with the complex ABC splitting pattern observed in terminal alkenes.
  • The IR is consistent with a simple unsaturated hydrocarbon.
  • The simplest structure which is consistent with all of these data would be a simple alkene bonded to a tert-butyl group.