NMR Takes the Field

Applications of the newly discovered property of nuclear magnetic resonance (NMR, see chapter 5) came very quickly. The Physics Department 

The accompanying figure also depicts a moderate resolution spectrum of pure ethanol with a trace of tetramethylsilane [TMS, Si(CH3)4] added to adjust chemical shift to a scale where the 12 equivalent hydrogen nuclei in TMS are set to zero ppm (this is called the 8-scale). The H-NMR spectrum of ethanol exhibits the following features  

1) Three discrete peaks downfield from TMS for the three distinct types of hydrogen in ethanol methyl, methylene and hydroxyl. 

2) The chemical shifts reflect the environment H attached to electronegative oxygen is most deshielded (8 4.8 ppm) the methyl group (8 1.1 ppm) is furthest from oxygen and least deshielded methylene is centered at 8 3.6 ppm. 

3) The methyl peak is split into a characteristic triplet (three peaks of 1 2 1 relative intensities) because it has two equivalent neighboring CH2 hydrogens. 

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