If there is an oxygen on one side of the methylene, all three neighbouring hydrogens must be on a carbon on the other side.Īlternatively, look at the spectrum the other way around. Mutliplicity usually only works with hydrogens on neighbouring carbons.
However, the shift of 3.5 ppm means that this carbon is attached to an oxygen. Otherwise, all three hydrogens could be on one neighbouring carbon. There could be two hydrogens on one neighbouring carbon and one on another. The carbon bearing these two hydrogens can have two other bonds. The integral of 2H means that this group is a methylene, so it has two hydrogens. Source: Modified from SDBSWeb : / (National Institute of Advanced Industrial Science and Technology of Japan, 15 August 2008) A quartet means that these hydrogens have three neighbouring hydrogens on adjacent carbons.įigure NMR20. This pattern is called a multiplet, and specifically a quartet.This peak is split into four smaller peaks, evenly spaced, with taller peaks in the middle and shorter on the outside.The peak near 3.5 ppm is the methylene group with an integral of 2H. The 1H spectrum of ethanol shows this relationship through the shape of the peaks.
In ethanol, CH 3CH 2OH, the methyl group is attached to a methylene group. That information helps to put an entire structure together piece by piece. Coupling is useful because it reveals how many hydrogens are on the next carbon in the structure. Another type of additional data available from 1H NMR spectroscopy is called multiplicity or coupling.