Proton NMR practice 1 | Spectroscopy | Organic chemistry | Khan Academy
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- Опубликовано: 30 сен 2024
- Practice determining the structure of a molecule from the molecular formula, hydrogen deficiency index, and proton NMR spectrum. Uses example of ethylbenzene. Created by Jay.
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When the 12 minute Khan video make makes a 2 hour lecture finally click ✌🏼🎉
ikr!!
Yes I agree. We go through powerpoint slides in class and it doesn't make sense to me. I watch this video and it becomes clearer on what to do. I took a quiz and looked at it as if I was in another country.
The 'Carbon next door' sounds like a horrible chemistry romance xD fantastic video though, really helpful!! Please keep doing these!!
the carbon next door, he said he just wanted to come over and chill, next thing you know, we're "bonding"
@@therealestg9 but then you decide to break things off with him, you just didn't have any chemistry
I found your step-by-step way of approaching these problems to be extremely helpful in explaining the methodology required in interpreting H-NMR data. In particular, the visual circling of protons on the chemical structures helps to reinforce your explanation regarding what each peak on the spectra shows us as we try to interpret. In explaining even the most minute details of your thought process, this video would serve as an excellent resource to students who feel as though they are behind, as well as advanced students who are simply seeking reinforcement. Excellent work.
Very helpful video. However, the volume is rather low that I'm straining to hear and have to back up and repeat to catch what you said. Looking forward to more with louder volume.
P.S. I'm viewing your video on a 2015 PacBook Pro using Chrome as my web browser if that helps.
could you please explain how do I obtain the integration value if not given by the examiner, our professor provide only the the compound the peaks is there a way to figure the integration values thanks
ahmed altaee if you find the answer of this question please share because i have a same problem doing this
@@iqrasyed7556 I think that in general you can reason that the peak is somewhat proportional to the number of protons, so a bigger peak should mean more protons. Maybe just with reasoning like that you can find out which peak belongs to which hyrogens? :)
What if you don't know the chemical formula? What if all you have is the Spectra data and some random info (i.e., you know that the unknown compound is insoluble in water, aq. HCl, aq. NaHCO3, and aq. NaOH and it's exact mass is 148.1 g/mol)
Thank you for making a 3 hour lecture that my professor gave us into a much more understandable
Videos are always good but I don't understand why the volume is always so low on all the videos.
I had the opportunity to use my knowledge of pNMR decades after learning when a Philadelphia-based Pharmaceutical Company had us characterize their API. It had an aromatic ring and an NMR profile that I reviewed in my capacity as GMP QA Specialist prior to releasing our CoA and data package to the Pharma Co. We had outsourced the NMR work to a subcontracting lab. They reported that NMR data was consistent with the structure of the API. Our Project Manager approved this before handing the package over to me. I clearly determined that the proposed structure was NOT supported by NMR. The ring substitutions were misplaced. I informed Management, they informed the Pharma Co. and they revised the structure of their drug. My request that we inform the subcontracting lab of their error fell on deaf ears.
My textbook rushed through this topic, especially the HDI. Didn’t show us how to calculate it but now I know :) very helpful
some people on khan academy deserve a medal! Jay is definitely one of them
these videos really helped in understanding NMR... thanks for uploading such educational videos.. keep up the good work !
At 9:17, he says the H's are in different environments but puts the under one signal. Can anyone tell me why these are considered equivalent when they are in different environments?
Give me an NMR after this! Im ready! Thank you!
This bullshit doesn't always work out.
You explained this exceptionally well. Thanks!
Awesome understanding. By keeping the Silverstein book and this video anyone can interpret the 1H-NMR spectrum. Thank you for the best video.
i didnt get these numbers 40 42 28.4 and 27
Those numbers are calculated by the computer and refer to the area underneath the graph of each peak. They are proportional to each other, so an integral two times as big as another one represents two times the amount of protons.
DUUUDE!!! GOD effing bless you. My Professor is cool, but she didn't explain this and we have a test on it. You are the MVP
I am overwhelmed. I have an exam to write in about five hours and this video is a great one. Straight to the point. Perfect!!!
After almost a whole term in grade 10 not understanding a thing about NMR spectroscopyI finally understand it after watching this 12 minute video. I finally get the relationship between molecules and their NMR spectrum. Thank you so much!!!
Can you turn the audio up in future videos please. I hardly watch Khan Academy videos because despite having my device's audio all the way up, the video is still hardly audible. I enjoy the videos though.
+Joshua Johnson change ur shit device or get hearing aid
stop hating
+zannatul Zan Wow, great input. Now let's find you something better to do with your time than providing hateful replies to other people's requests. Grammar courses for example. It would help me out also because then I wouldn't have to waste my time replying to morons like you.
It was a polite request, and it wouldn't have been asked had I not tried it on numerous devices. That's common sense. Now for the sake of not filling the comments up with junk writings, let's not comment unless we have something constructive to add. Thanks.
+Joshua Johnson +Joshua Johnson "Grammer courses for example" isn't a complete sentence. I won't mention the handful of other minor (punctuation and grammatical) mistakes you've made. Don't use grammar as your weapon if it's going to come back and stab you...
+Christian Rose says the guy who used, "you're" in, "Don't use grammar as you're weapon".
Brandon Barton I'm actually lmao at that. I can promise autocorrect was the culprit, but nonetheless I stand a perfect example of my own comment. At least I wasn't being a douche, though. Also, the period goes before the quotes.
how do you know how many protons each signal represents?
for the first problem, you look at the bottom numbers and divide each by the lowest number shown (27). For any half numbers you get (1.5) you multiply everything by 2. the number in total should match the amount of protons you have in your formula
so very helpful. I cant believe how fast I got this after being tortured by this for several lectures, understanding nothing. Thank you so, so much.
Learned it so many times but always need to come back to refresh lol
This is a really tricky topic for me to understand and going through examples is super helpful. Thank you!!
what if you don't have the integration value ???
then the test is curved
usually in Alevels we dont get integration values bcos sometimes the no. of H2 atoms on peaks are given, others u have to use the other techniques so its hard
around 8:50 how did you come up with the integration numbers?
Makes sense thanks! Got a chem exam Monday lol
Hey I have a doubt that can I draw the NMR spectra without leaving any gap in the baseline ?
Hdi=4 but benzene ring only fulfills hdi=3 ... Why another double bond didn't come?
hello, please how do you know the number of neighbouring protons when you have a multiplet peak?
this was so helpful i totally understand nmr now. Thank you so much :)
why the fuck would you jsut randomly multiple one by two and then not explain why you did so
How do you know that you have a carbonyl? I don't understand that part
But why did you make the ppm with big numbers
pplz speak loudly
even in handfrees voice is not clear
How to find integral value of peak.
Considering Knothe equation for determining conversion of methyl ester.in that equation there we need integral value of peak of methoxy protons that is 3.762
And value of peak of Alfa methelene protons is 2.31.But after getting this peak value how to find integral value of the same.??
Thw
God bless Khan Academy
Amazing explanation got perfect on my test, thanks!
why did you multiply it by 2 ?
because you obviously can't have 1.5 Hydrogens and the sum of the integration ratio needs to equal the amount of hydrogens in the molecule.
Toki Liam So, in the absence of full numbers I multiply by the arbitrary number: 2?
It mostly is 2 but it could technically be any even number bigger than 2. In this case, he used 2 because, he knew there were 10 hydrogens in total in this molecule. If you add up the integration value it must equal the amount of hydrogens in the molecule. Apart from the fact, that half a hydrogen atom cannot exist, the values before multiplying would have been: 1 + 1.5 + 1 + 1.5 = 5. Since we have to account for 10 hydrogens, you multiply the values by 2. If he had 20 hydrogens in the molecule, he would have multiplied the values by 4.
Oh, I see, thank you very much!
in our letures examples we do have these numbers 27.0 40.2 28.4 that we use to find the number of protons in each signal...is there other tecnic i can use
Hello everyone!
I have a problem with interpretation of nmr spectrum. I think I use coupling constant incorrectly. How indicate organic structure coresponding by using nmr spectrum?
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As far as I know the hydrogens on the Ring in the second problem are NOT chemically identical and would give different peaks. Perhaps they are so close that in practice the signal overlaps?
74379 Horacio Cliff
NMR made EASY!!!
I dont understand how you know the number of protons at each of the peaks. eg at 9.28s, if it wasnt given to you (5,2,3) how would you be able to tell?
@2minutes in, why do you multiply by 2 specifically? Any reason or just because it is a whole number greater than 1?
From Tanzania I appreciate the video .. I really understand NMR now
how to improve sound system in this nmr video on my j2 mobile. Regards. Dr. Bharath B. Regards.
this guy is so annoying how he tries to talk in the same way as sal
thank God for this video, I couldn't figure out how to do these problems. Now I have an idea :) Thank you soo much!
The ‘N-1’ law doesn’t apply to the green proton in the first spectroscopy, because the next door protons are not equal. It is a bit more complicated than that.
i apologize if im being stupid but why should we introduce H atoms on the benzene where as in the first question we draw another carbon next to carbonyl and add the hydrogen atoms there
what i infer from this is that we can't accommodate neighboring protons when it comes to benzene but still why has it got to be different
You said aromatic for 6.5-8 isn't it aryl? The structure was fine but the name wrong.
thanks man
great video
At 2:09 why you have Multiplied with 2 ? Is this optional to multiply with the no that gives exact no of protons
591 Horacio Valley
why multiply by 2? because of the formula (2N) for the chemical formula?
what happens when the spectrum doesnt have any values like you have? Just has the spectral data which is 0-12?
why are we concerned about the number of neighbors for the 2 peaks on the right side, but not the peak one the far left?
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Where we can see this integration value
386 Oswald Parkway
Shoutout to this video for teaching me better than my ZOOM ochem meetings
Very nice explanation!
It shows how beautifully elegant NMR spectroscopy is!
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thank you so much for explanation, very clear!
literally saved my life
this account is going to be my savior for my ochem exam on friday
What do you do if the values don't match and you have too many singles in your proton nmr?
THANKKK YOUUUU!!!!!
your explanation is much better than my prof.
Why is HDI 1 not 2?
bc 2/2 = 1 (use formula to find double bond equivalents)
what is the hight of the peaks represent, I don't get that
why is it multiply by 2?
why cant professors just teach like this?
some people on khan academy deserve a medal! Jay is definitely one of them
When you say you're accounting for the protons, are you specifically talking about hydrogen? And not the protons in the nuclei of any other atoms/elements?
yes
The video that finally clears up all the confusion! Thanks so much.
A question I have is at around 8:50 in the video we have the proton numbers (5,2,3) given. How did you arrive at that?
Briggs Hightower given in the qn
This video is very helpful. Thanks so much.
If I could five you 10000 likes I would!
THE BEST!!!!
where do this speaking guy live i wanna Thank you in person
ghonchi monchi
Thankyou
thanks
Nice presentation, its useful for me, noise in audio. "je vous remercie"
Thanks you so much!
Thank you so much :)
explained it really well, thank you !
why did you multiply everything by 2?
To get a whole number amount of protons. You can't have half a proton. The ratio remains the same
Makes complete sense. Nice.
What s your name
Didnt you miss a double bond in the second example ??
+Otman Shouli No he is right. The reason why you think that is because you forgot to take the hydrogen atom away from the carbon atom in the ring ( which gave it fourth electron the delocalised ring) that is bonded to the ch2ch3 group.
+nightman890 oh yeah totally missed that. Thanks for the answer :)