How Would You Use 1h Nmr Spectroscopy to Distinguish Between the Following Two Compounds
Video Transcript
Okay, So this problem covers looking at different ways that we can distinguish a proton NMR spectrum. Um The main keys that we've learned so far are shielding and the shielding effects. And in this specific section we learned about the number of signals. So the first thing that we look at here is the number of signals will be able to look at the number of signals and distinguish all three of these from each other in an NMR spectrum. So when we look at the first molecule, so I have it in the standard form that you have in the book, and I also have it in just bottom line for him off to the right here. Um I like bond line form because it's very easy to see symmetry symmetry is going to dictate that basically everything on the left side, it's gonna be the same as everything on the right. So, you know, to hydrogen is here, Right. And we have three hydrogen. Yeah, on this carbon. Okay. Um obviously we know looking at this compound that these two sets of hydrogen are very different. Um if there's really any way that you want to look at these to tell them apart is being different. Is easy enough. The easiest one is probably just the fact that this is the CH two and this is the CH three. That's enough difference to be a difference. Yeah. Um when we think about numbers of positions, obviously this is one too right. And because everything on the left is the same as everything on the right, that means that this is Essentialments position one again and position to again. Yeah. Okay. So this molecule has two signals in a proton and a mark. Mhm. That compound very similarly has symmetry through this oxygen. Okay. Yeah. Again, we take this carbon can't have many hydrogen is we have attached to it. All right. And we look across this reflection, we see ourselves. Right. We can think of this little little dotted line as a mirror. So, if on this side That's position # one. This is also position # one. So, this molecule would only give one signal in a proton NMR. Okay. Remember a proton NMR. What are we actually going to get a signal from protons? Right. So unless you are a hydrogen, you are not producing the signal in a proton NMR. Mhm. This last one has a little bit different look. Um I've drawn it specifically in this form for bond line because it's very easy to see in terms of the symmetry. Okay, we have a nice little line of symmetry going down the center here. We can look at all the different positions in this molecule, starting from an end. All right, So this is a CH three. Sitting out here. This is a CH two. Okay, so that alone is a difference. Therefore those two positions are different. This is a carbon with no hydrogen. So we don't have anything to worry about here. And finally this is a carbon with three hydrogen. Okay, so now we have to distinguish is this carbon with three hydrogen different than this? Carbon with three hydrogen? Okay, so This carbon is one bond from an oxygen. This carbon is three. That's a difference. And that's enough to make those two positions different. When we count up the number of different positions with hydrogen. We have one, two and three. And again because it's like looking in a mirror, all of these positions have a duplicate. Okay. And therefore this compound would have three signals in a proton NMR. Mhm. Okay good. Yeah.
How Would You Use 1h Nmr Spectroscopy to Distinguish Between the Following Two Compounds
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