So we're missing eight Hydrogens or missing four pairs of Hydrogens.
So two times eight is 16, plus two is 18. So if we have eightĬarbons, then we can have a maximum of two timesĮight plus two Hydrogens. So we have a molecular formula of C8 H10. Sure to count all of your atoms and you will get, of course, five Carbons, ten Hydrogens, and one And then, we already talkedĪbout the blue protons, right? Having zero neighbors. The red protons have? Here's one and here's
All right, so let's thinkĪbout the red protons again. So we're gonna go with it because all we care about is getting the structure of our molecular here. Of the N plus one Rule isn't quite true but it Magenta and red protons are actually in different environments. So five neighboring protons, matches what we see on the NMR spectrum. We expected five neighborsįor these CH2 protons. All right, so let's thinkĪbout how many neighbors. And so let's go ahead and draw in our CH2. That these methyl protons are next to two neighbors and so we must have aĬH2 next to that methyl. So these protons right here in red are giving us this signal. So we have our methyl protons right here. Protons for the methyl group must be these two protons right here. So these must be the furthest away from the carbonyl, all right? They're not being deshielded as much as the two signals in this direction. Now these two signals, this signal here and this signal here, we're talking about under two parts per million now. So we will expect two neighboring protons. How many neighbors? Well, we have one, two, three peaks. Three protons, all right? That's a methyl group, so CH3. Six minus one is five so we will expect five How many neighboring protons? All right, let's count Neighboring protons, all right? So those protons are on this carbon and the next door carbon So these protons in blue here, these three protons are We'll draw in our methyl protons, right? Being deshielded because So this signal is deshielded, all right? So these protons must beĭeshielded a little bit. What about the chemical shift? The chemical shift for this signal is once again past two parts per million. How many neighboring protonsįor those methyl protons? Well, there's only one peak here. We know that because of the shift, right? The carbonyl, the oxygen deshields these two protons a little bit and gives us a higher valueįor the chemical shift compared to something Sense because we calculated an HDI of one indicating their (mumbles) double bond present and we need to account for an oxygen in our molecular formula.
And that's in the region forĪ proton next to a carbonyl. So the chemical shift for this signal is between two parts per million and 2.5. We have to do is subtract one to find out how many neighboring protons. The N plus one Rule, if you have N neighbors, How many neighboring protonsĭo those CH2 protons have? All right, so we can figure that out by the number of peaks on the signal. Next, let's look atĮach signal one by one. So now we have accountedįor all 10 protons using our integration values. So if we add all those up, two plus three plus two plus three, that's, of course, 10 protons. And if we multiply 1.5īy two, we get three. So if we multiply one by two, then we get two protons. And we need to accountįor 10 total protons here. The relative numbers of protons giving you these signals but you can't have 1.5 And 42.2 divided by 27 is once again pretty close to 1.5. 40.2 divided by 27 is pretty close to 1.5. For this signal, there'sĪn integration value of 27. Think about a double bond might be present in this So therefore, the Hydrogenĭeficiency Index is equal to one. Here we have only 10 Hydrogens so we're missing two Hydrogens. So 12 is the maximum number of Hydrogens.
So two times five plus two is equal to 12. Have is two N plus two, where N is equal to five. And so if we have fiveĬarbons here, the maximum number of Hydrogens we could The first thing you could do is calculate the Hydrogen Deficiency Index.