Problem #5: The molecular formula for an unknown compound is C8H10O2. 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 #5: C8H10O2

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 Problem #5: C8H10O2

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 Problem #5: C8H10O2
13C NMR: quartet: 56.0 ppm triplet: 71.0 ppm two doublets: 114.3, 128.3 ppm; two singlets: 133.2, 160.9 ppm

Problem #5: C8H10O2

  • The molecule contains two oxygens, and from the analysis, contains four double bonds, carbonyls or rings. The large number of degrees of unsaturation strongly suggests an aromatic compound (DU = 4).
  • The mass spectrum displays a molecular ion, which is the base peak, an m-1 and an m-17, all of which are consistent with a simple alcohol.
  • The 13C spectrum contains six peaks, indicating that the molecule has some elements of symmetry. The quartet at d 56 and the triplet at d 71 represent a CH3 and a CH2 group which are deshielded by electronegative atoms (most likely oxygen); the peaks at d 161 - 128 are in the aromatic region; the fact that two doublets and two singlets are observed strongly suggests 1,4-disubstitution.
  • The proton NMR also shows evidence for aromatic 1,4-disubstitution and suggests that the methyl and methylene are isolated and adjacent to electronegative groups. A peak consistent with an alcoholic OH can also be seen.
  • The IR is consistent with an aromatic alcohol containing no carbonyl group, suggesting that the second oxygen is involved in an ether linkage.
  • The simplest structure which is consistent with all of these data would be an aromatic compound containing an alcohol group and a methyl ether, situated 1,4 relative to each other.