H NMR Spectroscopy Review - Examples & Multiple Choice Practice Problems
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- เผยแพร่เมื่อ 7 ม.ค. 2025
- This organic chemistry video provides a review of H NMR spectroscopy. It provides plenty of examples and multiple choice practice problems that you might encounter on your next test or exam. It discusses chemical shifts for common functional groups such as aldehydes, carboxylic acids, ethers, alkyl halides, and aromatic benzene rings. It provides a review of the H NMR signals and the spin spin splitting pattern of the n+1 rule that you need to know. It also shows you how to determine the number of signals in an h nmr spectrum and discusses the terms upfield and downfield so you can understand it.
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Here is a list of topics:
1. Common Chemical Shifts / H NMR Table Values
2. How To Find The Number of Signals
3. N + 1 rule - Spin Spin Splitting
4. How To Identify Identical Hydrogen Atoms
5. How To Draw a HMR Signals /Spectrum
6. Upfield vs Downfield
7. H-NMR Analysis and Integration
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Might as well be giving you my tuition money… doing a better job then my teacher. Thanks for this!
same here
Than
Patreon it is then
at 5:38 - a simplified version of the n+1 rule was applied to get a quintet (5) for signal B. Even though most spectrums will show a signal that appears to be a quintet for this type of situation - it does not give the most accurate description of what is happening. The quintet signal is really an overlap of other signals. Proton A (3H) splits proton B into a quartet and Proton C splits proton B into a doublet giving us either a doublet of quartets (2 x 4) or a quartet of doublets (4 x 2) which gives us a total of 8 signals. Some spectrums won't show 8 signals but may show 5 due to an overlap of signals. Nevertheless, the simplified N+1 rule can still be used to help you get the right answer in some situations but it does not reflect what is truly happening in the molecule. A similar situation applies when protons B and D split the signal corresponding to protons C.
5 years after this video and you're still saving lives. My professor explained the doublet, triplet, etc as, "You look like like your neighbor on NMR. So does a Russian and an Italian look the same? No. But when they are neighbors on the NMR they look like each other." No idea what the hell he was talking about. Thank you for the simple explanation.
that's kinda racist ngl
Super helpful on H-NMR, the night before the EXAM... I appreciate videos likes these.
hope ur exam went well :)
As an O chem tutor there is nothing nicer than your videos to refresh my memory on the material I purposely forgot.
Bro, I was following you and understanding your lecture. Thank you.
What I love from u is that, despite oof how much I dont like this topic, you make me enjoy it. Thanks man!
The fact that your voice is also so soothing makes this 10x better. Thank you.
Just wanted to say thank you for posting such great videos. Because of your reviews (and some work on this end internalizing your lessons), I did really well on the ochem portion of the DAT. And, now that I have to take ochem II, this video is about to save me the embarrassment of having forgotten literally everything I knew about NMR. Ha! So, yeah, thank you for taking the time to do such a great job. It's having a real, measurable impact on my life.
Hi Nicole, I'm glad those videos prove very helpful to you. Thanks for posting this comment. I really appreciate it.
Hi Nicole
Our teacher is literally giving us nmr (proton and carbon), mass spec, and ir and telling us to come up with a structure
Same here. I´m afraid lol
It's fun trust me😂
Just google the molecular formula and add the functional group u obtained from ur ir then google should be smart enough to do ur work for u
@@Hehexddddd This won't help on the ACS
Same here mate...just that the mass spec is missing..we have the molecular formula instead..
You really are the chemistry god LOL. Thank you so much for creating these videos. I've been watching them since Gen chm I and now im in Orgo II. Sooooo helpful.
"spin spin splittin" love how you say that, haha thanks for your help.. This channel gets me through life
you are a lifesaver. I go to lecture and it is all just a blur by the time I walk out & reread my notes. the text is useless. we have guided prctice on campus but we dont get through much in each session. in other words, I don't know what I would do without you!!
aced my spec test could not have done it without your help thanks so much again and again and again!!!!!!
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OChem midterm in 5min and what do I watch? Thank god for this guy.
This helped me understand spin splitting way more than my class did. Thank you
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i had been learning this for weeks and didn't understand it until right before my spec exam, only missed 1! thank you !!!
Splitting patterns which you explained was really good;understood the exact concept and also after solving some problems..
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Thank you for this, you have saved my ass multiple times
I have a question about the second multiple choice practice problem. I believe option "D" should have just 4 signals and not 5. 20:00, B and C should appear simultaneously. As soon as you can get back. Thank you!
Thanks Mr, you people your really helping us a lot, like i can learn things even when iam still in the holiday
be blessed Mr i was following you are lesson actually i got new concept
You save my life. Thank you very much ❤
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not like my teacher in class 🙄😑
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How is E 15:04 different than the Ds. The hydtogens are both attached to a carbon whose adjacent carbons are both secondary.
Yes, I need clarification with this question as well
YES PLEASE i understand how this is years later and clarification still hasn't been issued but here's to hoping someone knows the answer :/
thnx a lot sir ..it help me a lot in Mphil
Much more love, much more respect bro.
Saved my life❤️
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Better Understanding👌
My Great teacher...
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You should make one on Carbon nmr
You are an angel, a lifesaver!!
Very useful video, thank you so much!
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Wouldn't the Hydrogens on the CH2 next to the chiral carbon in the first example produce two different signals? Or am I mistaken? That was a chiral carbon bonded to the bromine, correct?
Heather Begley ... Yep. Those hydrogen's are diastereotopic. He made a mistake
Why is that?
You are right
Why would the two hydrogens on the CH2 produce 2 different signals? They're in the exact same spot with the exact same effect. They are both 2 carbons away from bromine. So they should produce 1 signal
They're in the same chemical environment. They are attached to the same carbon atom so they would only show as one signal.
Why @ 15:00 is E it’s own signal? Does it not have an identical chemical environmental to D with two adjacent H’s?
I did not understand that one either. It's adjacent to secondary carbons as well ...
I think I just figured that one out lol. It's more distant from the oxygen, you could compare it to the example before and see why that one had carbons with the same environment.
Yes but it's a carbon further away from oxygen than D. You can't just look at the close neighboring atoms, you have to look at the whole molecule.
at 13:48 why would it only be 2 signals and not 3? if you draw the line of symmetry aren't there 2 more groups unaccounted for?
Bro you saved my life
Please make videos for C-NMR and Mass spectrometry. I am welling to pay for both videos. All I care about is to pass these two complicated topics
Shouldn't the protons on the B Carbon at 4:05 be a tad bit further downfield (say 1.2-1.3) due to being closer to a partially positive CH? Just like the CH3 is on the D Carbon.
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Thank you sm❤
awesome video, just wondering... 5:30 because the a and c protons are not equivalent shouldn't the N+1 rule be applied individually to each proton to find the signals for b? that would give a doublet of a quartet right?
Carlos Del Carmen thats what i thought. I thought the rule was if a hydrogen has two adjecent atoms with hydrogens of different signals. Then the rule is (n+1)(m+1)
@@kingkaigus3222 what's m?
no, they are too far apart. They have to be within 3 bonds of each other to split...within 4 bonds if there is a double or triple as one of the bonds
You da REAL MVP
I understood more in a 30 min video than i did in a whole month of class
you saved my degree!
I don't understand how the example at 15:00 has symmetry at where he put a dotted line. Can anyone help me out? I think he place a D and the E in the wrong place.
The pi electrons of the aromatic ring aren't localized as he draws it.
Also, at about 5:45, why are you not complex splitting the B and C hydrogens? You're doing the n+1 rule, even though the environments (the adjacent beta-hydrogens on each side of them) aren't equivalent? Why??
Nice bro . keep it up
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Please can you make a video on heterotopic, enantiotopic, diastereotopic, and homotopic hydrogens? It’s in the curriculum now.
Kindly, Turn on the Captions so that some people like me need not to run again the video to get your words ....
thank you!
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@5:17 Aren't the two protons on the CH2 different since they are diastereotopic?
you are a god amongst men
Why 5:32 hydrogens B are not doubled of quartet ?
Why doesn't the carbonyl carbon get a signal at 9:00?
Paige Campbell Only carbons that have hydrogens directly bonded to them will get signals
@17:36 why isn't the C=O a signal? Wouldn't that make the compound have 4 signals? (You only marked 3)
uR #Work is qreat
are we allowed to post videos too???
Thank you !!
In the first example (4.25), A and D carbons are primer. Why one of them is 0.9 other one is 1.0??? Thank you for your videos.
the one which has 1.0 is more nearer to the electronegative atom so more deshielding (for 1.0 one) and so more magnetic field(or resonant frequency) is required.I hope that solves your doubt.
pls make more videos o n this topic
Thank u mark wahlberg
What if you don't know the chemical formula? What if all you have is the molar mass, IR and C and H NMR data?
Rule of 13
Thank you 🙏🇧🇷
do you a review video on NMR in HD?
In the first question the ch2 has non equivalent hydrogen atoms next to it attached to ch3 and ch in different chemical environments so wouldn't complex spin spin coupling or signal splitting pattern occur so would the n+1 rule hold or can we just ignore it
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Love your videos! Quick question, my prof specifically said never to add neighboring hydrogens (for e.g. In the first problem when you added 1H + 3H for a CH2 carbon), and that it wouldn't turn into a quintet but into a doublet of quartets, so where you just simplifying the problem for this video purposes? Does that still stand for the same thing? And is it wrong?
I saw what you just said in another video and got confused as well
That's only when the magnetic ambience of the hydrogens differs, the n+1 rules fails in these cases.
What about OH and NH🤔🤔
why translation is not found in this video
u saved me
I guess you could. Those aren't really similar things, but I'll let it slide. :0
Sir,you did'nt tell about chiral centre...there should be 5 signals in 1st example. is'nt .?
That was the video that saved my ass
i need subtittles please 😊
so where can i mail you my degree?