1H NMR

#Chemistry 

Integration

• The area under the curve for a signal corresponds proportionally to the number of hydrogens that emit that signal

Peaks vs Signals

• Each group of equivalent hydrogens produce exactly one signal
• These signals can be composed of 1, 2, 3, 4, or multiple peaks. We then may say a signal is split into/has a multiplicity of a singlet, doublet, triplet, quartet, or multiplet

Chemical Shifting

• A greater chemical shift in NMR means a lower $\nu$ relative to that of TMS
• Downfield (deshielded or more polar) molecules have greater chemical shift
• Upfield (shielded or more nonpolar) molecules have less chemical shift
  
  
  

Signal Splitting

• $(n+1)$ rule
  • ${}_{}^{}{}_{}^1\mathrm{H}$ NMR signal is split into $n+1$ peaks, where $n$ is the number of non-equivalent hydrogen neighbors
  • Only applicable if the hydrogen neighbors are the same or similar in coupling to each other
• Coupling Constant $(J)$
  • Describes the separation between two peaks in a signal
• Vicinal Splitting
  • Caused by hydrogens vicinal to each other
  • Follows Karplus Equation
• Geminal Splitting
  • Caused by hydrogens geminal to each other
  • Splitting is much smaller than that caused by vicinal splitting
• Benzene Protons
  • Can couple only with each other to produce multiplets
• $-\mathrm{OH}$ and $-\mathrm{NH}$ show up only as singlets
• Complex Splitting
  • Honestly, just check out Notability notes in CHEM 30B