Spectroscopy of Alcohols and Phenols

Alcohols have a strong C—O stretching absorption near 1050 cm and a characteristic O—I I stretching absorption at 5300 to 3600 cm h The exact position of the O—H stretch depends on the extent of hydrogen bonding in the molecule. 

Unassociated alcohols show a fairly sharp ahsorption near 3600 whereas 

Problem 17.18 Assume that you need to prepare 5-cholesten-3-one from cholesterol. How could 

Carbon atoms bonded to electron-witlidrawing —OH groups are deshiclded and absorb at a lower field in rhe XMR spectrum than do typical alkane carbons. Most alcohol carbon absorptions fall m Lire range 50 to 80 5, as the following data illustrate for cyclohexanol  

Phenols, like all aromatic compounds, show H N 4R absorptions near 7 to 8 5, the expected position for aromatic-ring protons (Section 15.8). In addition, phenol O-H protons absorb at 3 to 8 5. In neither case are these 

Problem 17.18 Assume that you need to prepare 5-cholesten-3-one from cholesterol. How could you use IR spectroscopy to tell whether the reaction was successful What differences would you look for in the IR spectra of starting material and product  

When the H NMR spectrum of an alcohol is run in dimethyl sulfoxide (DMSO) solvent rather than in chloroform, exchange of the 0-H proton is slow and spin-spin splitting is seen between the O-H proton and C-H protons on the adjacent carbon. What spin multiplicities would you expect for the hydroxyl protons in the following alcohols  

Most alcohol carbon absorptions fall in the range 50 to 80 8, as the following data illustrate for cyclohexanol  

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