In your experiment the product is characterized using IR spectroscopy, because t
ID: 480269 • Letter: I
Question
In your experiment the product is characterized using IR spectroscopy, because that is easy for you to do in the lab. However, NMR spectroscopy is usually much better for characterizing organic structures. Describe IN WORDS, how you would distinguish the product bromide form the starting material alcohol using proton NMR spectroscopy. You can use the provided structures in your explanation, Do not attempt to distinguish them based on absolute values of chemical shifts (i.e., don't make statements such as "the chemical shift of protons X should be 3.86 in the bromide and 3.65 in the alcohol"), there is another much simpler way of distinguishing the structures.
Explanation / Answer
In the NMR spectrum of alcohol, there will be a broad peak for OH group. We can take advantage of rapid OH exchange with the deuterium of heavy water to assign hydroxyl proton resonance signals which removes the hydroxyl proton from the sample and its resonance signal in the nmr spectrum disappears. Experimentally, one simply adds a drop of heavy water to a chloroform-d solution of the compound and runs the spectrum again.
The peak corresponding to OH group will disappear in the nmr spectrum of product bromide.