Propose a structure for the following compound that fits the following 1 H NMR data: Formula:C 2 H 4 O 2 1 H NMR:2.1 δ (singlet, 1.2 cm) 11.5 δ (0.5 cm, D2O exchange)

Hey guys. Let's take a look at the following question dealing with structural determination. So here we say, Propose a structure for the following compound based on the proton NMR data that I give to you. The first thing we want to do is figure out the IHD. So 2C+N minus H, all in brackets, plus 2 divided by 2. We have 2 carbons, so 2 times 2 is 4. No nitrogens but 4 hydrogens. That becomes 0 +2 which is 2 divided by 2, so we have an HD of 1. Now, what we do next is we take a look. We have these integration values. But in this question, we really don't need them because here what we need to realize is we have a signal which is unique. Only one type of proton will give us a signal between 11 13. That means that this is a carboxylic acid. Now, here I also include in this question D2O exchange. Now, D2O is deuterated water. Now remember, deuterium is an isotope of hydrogen. Now, when they're saying D2O exchange, that indicates that we have an Oh group present because what does this do? If we have an Oh group present and we use D2O on it, what it does is it actually replaces that signal is deuterium is NMR inactive. So that signal will disappear. So if we have an unknown and they say, they use D2O on it and the signal disappears, that's an indication that we have an Oh group present either from an alcohol or from a carboxylic acid. Anyway, since our signal is 11 point 5, we know we have a carboxylic acid, so we know we have at least this portion of our molecule. Then the question becomes easier because here our formula is C2H4O2. The carboxylic acid that we know we have has what in it? It has a carbon in it. It has 1 hydrogen in it. It has both oxygens in it. So what do we have left? A CH3 that's not being used, which would mean that this compound here is connected to a CH3. Here we have acetic acid or ethanoic acid. This would be the identity of our unknown compound. Remember, once you figure out the IHD, what we typically do is we go to the integration values to figure out what types of hydrogens groups are present. But if you have a unique signal such as carboxylic acid, then you focus on that and we know we have that portion. From there, we can deduce what the rest of the molecule would look like.