Question

which occurs at a larger wavenumber: a. the c-o stretch of phenol or the c-o stretch of cyclohexanol? b. the c=o stretch of a ketone or the c=o stretch of an amide? c. the c-n stretch of cyclohexylamine or the c-n stretch of aniline?

Answer 1

Electron delocalization causes the of the phenol to have partial double bond character, whereas the of the cyclohexanol is a pure single bond. Again, we know as the bond order or bond strength increases the absorption occurs at larger wave number. So, the stretch of the phenol occurs at larger wave number.