PART 10: PROTON NMR SPECTRUM OF ETHANOL (PROTON EXCHANGE)
Автор: TETRAHEDRON CHEMISTRY CLASSES
Загружено: 2020-01-26
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Note: At time 4:48 "Rapid Chemical exchange decouples spin interactions, and the NMR spectrometer records only the average environmentit senses for the exchanging proton. Thus in average environment "H" is present on "O" atom of alcohol and give its peak as singlet but will not couple with methylene hydrogens.
In this lecture, I have explained the difference between the NMR spectrum of impure ethanol and ultra-pure ethanol. If alcohol contains traces of water, acid or base then spectrum is simple and no spin spin Coupling occurs between methylene hydrogens and hydroxyl hydrogen. Thus spectrum shows 3 peaks, singlet for OH proton (bx in reversible and fast proton exchange between water and alcohol, NMR sees average presence of hydrogen on OH group of alcohol), methylene gives quatrat and methyl gives triplet. On the other hand in ultrapure sample, no exchange of proton occurs thus methylene protons first couple with methyl to give quatrat and then this quatrat couples with OH proton to give overlapping pair of quatrat.
#Ethanol #ProtonNMR #Couplingconstant #Protonexchange
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