NMR Spectroscopy Two
Vložit
- čas přidán 2. 08. 2024
- This video builds on NMR Spectroscopy Visualized and discusses in greater depth several concepts which will help you to make the connection between molecular structure and the resulting NMR spectrum. Spin-spin coupling (J-coupling) is explored in depth with several examples provided. We will explain the difference between vicinal and geminal coupling and show examples of diastereotopic protons. We will also explain magnetic anisotropy and how it is responsible for the characteristic chemical shifts of aromatic protons. Another important tool for the interpretation of NMR spectra is integration, and we will look at a couple examples of using integration of peaks in NMR.
Suggestions for further reading.
NMR theory (general):
chem.libretexts.org/Bookshelv...
Spin-spin coupling (J coupling) and the N+1 rule:
www.chemistrysteps.com/splitt...
Diastereotopic protons:
www.masterorganicchemistry.co...
Diamagnetic anisotropy:
www.khanacademy.org/science/o... - Věda a technologie
Perfect explanation. Please make more videos on spectroscopy !
Pl recommend me a full video on CZcams to understand to elucidate any chemical compound by nmr
Lectures that cover all things.
This has to be the best H-NMR video on CZcams! Very well done.
Great video! I have trouble explaining these concepts to others and this video and your first NMR video really helped me learn how to explain in a simple straightforward way
Thank you very much, Peter. Glad to hear that the video was helpful.
Pl recommend me a full video on CZcams to understand to elucidate any chemical compound by nmr
Lectures that cover all things.
Really helpful video, thank you so much.
Thanks! Glad to hear that it was helpful.
In part one, you forgot to mark the concrete value of ppm (frequency) which may confuse us to understand (4:20). Hope you add the relation between ppm and frequency. An excellent video. Thank you for your sharing.
Thanks 👍
well explained . very good video and really helpful. thank you!
Pl recommend me a full video on CZcams to understand to elucidate any chemical compound by nmr
Lectures that cover all things.
thank you so much!!
Great video!
Thanks!
Thanks
thx
it was really helpful video and your presentation was very effective. could you explain about 2D nmr and x ray crystallography by this type of presentation? it would be helpful.
Pl recommend me a full video on CZcams to understand to elucidate any chemical compound by nmr
Lectures that cover all things.
I learned clearly from animation than textbook . thanks
Pl recommend me a full video on CZcams to understand to elucidate any chemical compound by nmr
Lectures that cover all things.
Great video :) Quick question: If shielded protons generally align slower to the magnetic field after being pulsed, why is it that they appear to have a higher frequency?? I mean, they align slower, therefore spin slower into the aligned state and should have a lower frequency, no? Or is the reciprocal axis inverted?
You have it correct. The high frequency is to the left and the low frequency is to the right. The X-axis is in ppm where ppm = ((frequency of the peak - frequency TMS)/spectrometer frequency) X 10e6. Notice that the left hand side of the axis is large positive numbers and the right hand side is small positive numbers. So it's like the X-axis is flipped. For more on this topic please see
chem.libretexts.org/Bookshelves/Organic_Chemistry/Map%3A_Organic_Chemistry_(McMurry)/13%3A_Structure_Determination_-_Nuclear_Magnetic_Resonance_Spectroscopy/13.02%3A_The_Chemical_Shift
@@ScienceSketch Perfect, I asked before I saw the ppm axis. Thanks for your answer! :)
All of my doubts are cleared now regarding NMR data interpretation. please make more videos on spectroscopy 🙏
Pl recommend me a full video on CZcams to understand to elucidate any chemical compound by nmr
Lectures that cover all things.
Sir pl suggest how yo learn structure elucidation
Another excellent video. Even better than the previous one because you talk a bit slower in this one.
Thanks for your kind words, babayaga. I have tried hard to make improvements to the narration and audio quality...and there's still room for improvement! I would hope that anybody who has trouble understanding would take advantage of the closed captions (CC).
Pl recommend me a full video on CZcams to understand to elucidate any chemical compound by nmr
Lectures that cover all things.
that may called prototype non other which makes a continuous combustion of the element.
Why is it again that shielded nuclei have larger peaks?
how do you create the animations ? please help me.
Pl recommend me a full video on CZcams to understand to elucidate any chemical compound by nmr
Lectures that cover all things.
You make the point that neighbor protons don't split each other if they are in identical location environments in the molecule. This presumably is because both electrons resonate at the same frequency and in effect flip together and always remain in the same relative orientation to each other. Can there be the case where some molecules in the sample are not all in the ground state in which case one would see a split. For instance if there are two Ha protons in a molecule they could be anti-aligned in the ground state of the molecule, can there then be an excited state where they are instead aligned and thus feel a different field do to their neighboring Ha? Or, does such an excited state not exist because the molecule would fall apart with this different alignment.
Hi Howard, nuclei in identical environments do couple to each other, however no splitting is observed in the spectrum. When two equivalent nuclei couple, transitions between energy levels do not change because the interactions between the nuclear moments are the same.
Please see the NOTE section here:
chem.libretexts.org/Courses/Pacific_Union_College/Quantum_Chemistry/14%3A_Nuclear_Magnetic_Resonance_Spectroscopy/14.07%3A_Spin-Spin_Coupling_Between_Chemically_Equivalent_Protons_is_Not_Observed#:~:text=Spin%20coupling%20comes%20from%20a,levels%20of%20allowed%20spin%20states.&text=Spin%20A%20(shown%20in%20red,both%20of%20which%20are%20equivalent.
The protons are either aligned with or aligned against the magnetic field, and the NMR spectrum is picking up the energy change when protons flip from one to the other. I don't know about the situation where a molecule is in an excited state and how that would change the nuclear moments. The following presents spin-spin coupling in more detail:
chem.libretexts.org/Bookshelves/Analytical_Chemistry/Supplemental_Modules_(Analytical_Chemistry)/Analytical_Sciences_Digital_Library/Active_Learning/In_Class_Activities/Nuclear_Magnetic_Resonance_Spectroscopy/03_Text/04_Nuclear_Coupling
Pl recommend me a full video on CZcams to understand to elucidate any chemical compound by nmr
Lectures that cover all things.