NMR Coupling Constants in Organic Chemistry

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[@missmegan9208]

why cant my university explain concepts simply like this... great video

[@alimohammedzaki1830]

Same question 🤔 in my head 😆 LOL

[@himanshig5672]

Point to point details. Thank you sir

[@Shwetabatra24]

Hello sir All ur videos are top class ... Just wants to request to please a video on nuclear overhauser enhancement n it's origin...pls I m not getting that concept...pls help

[@villagetv3897]

Fluorine influence Will be there in splitting

[@plamenpenchev262]

Yes! Fluorine splits both doublest in both compounds. We will have in each compound dd and dd. I am surprised by this error of the lecturer! If F is Cl the reasoning will be correct. Even in Plovdiv Uni (Bulgaria, not so developed country) I teach my students of heteronuclear Js.

[@scorpianguitar]

I see that the J value is larger for trans than it is for cis alkenes, and I've seen that the karplus equation predicts this result: that J is larger for a dihedral angle of 180° than it is for one of 0°, but this equation and other variants have empirical constants and are good approximations of J for specific dihedral angles and electronegativities to match what is observed. However, I still do not understand what is physically occurring to make this happen. I don't believe it's an anisotropic effect because in both cases, the protons are equidistant from the double bond ring current. I don't believe it's a through-bond interaction (exclusively fermi contact, Pauli exclusion principle and hund's rule) because the bond length is the same. I am left to believe that it is simply spatial- that cis protons have a larger effect on one another than trans. But my intuition following this is that a larger effective Bo from vinylic protons would result in a larger energy difference between the parallel and antiparallel nuclear spins observed (a larger difference in energy and so a larger J) Any help with understanding of the physical mechanism would be greatly appreciated. By me as well as others asking similar questions here, I'm sure. Thank you

[@origamigek]

I also do not understand this at all, which is why I watched the video in the first place. Might have to ask an NMR expert because I've asked around and people cannot explain it to me in a satisfactory way. As of now I am stuck with: the larger the E diff between the protons and the larger the interaction, the bigger the Jc. Perhaps the cis protons are closer and have a stronger interaction through space but it is offset by a smaller E diff, giving the trans protons a larger Jc still. Or there really also is a stronger interaction through the pi bond in a trans manner, stronger than the cis arrangement. It does feel like that would make sense as the trans protons and the pi bond are roughly on a straight line whereas the cis arrangement is bend. But I have no idea really.

[@origamigek]

Looks like my intuition was somewhat correct! kzbin.info/www/bejne/jYaXeol9q9ada7c

[@PrabjotGhumman84]

Thank you so much for your descriptive explanation. sir may i know why the coupling constant for trans is higher than cis isomer.

[@Shwetabatra24]

Prabjot Ghumman same ques I have...have u got the answer ? If then pls xplain

[@rajamanokharatturperiatham6978]

I believe in this case, the B effective magnetic field on a&b in Trans is less, so the J value is high for Trans and the vice-versa for Cis.

[@naseemkaniyath4720]

Informative From Qatar..

[@user-kt2xo4yp2j]

Thanks i got inc grade and this helps

[@cheemosalik9129]

Thank you sooo much sir for a brilliant explanation

[@charliezhu163]

Brilliant explanation!

[@ataradhussain3943]

Nice vedio clear lot off concept

[@victoriaahmadi577]

But what about those cases when geminal H-atoms have different shifts but are attached to the same carbon? Will the J-coupling constant be the same for these two? If it will, how can we tell that two signals with different chemical shifts are signals for H-atoms that are adjacent to each other and not bonded on the same carbon?

[@goutamdebnath1427]

সেরা সেরা। thanks

[@nicolekofman2745]

you're amazing

[@Alchemist_171]

Thank you.

[@901chimera]

So to do this, i would need to know the distance in ppm?

[@atelier.d_atom.]

thanks a lot !

[@parmodsharma3507]

How do we find the value of resultant nuclear spin??

[@parmodsharma3507]

For example it's value for boron is 3/2,for oxygen it's value is 5/2 ???

[@alessandradichio991]

thank you!

[@shadowknight743]

You're welcome!

[@samirabougataia3148]

Supertop

[@shivalidhingra1911]

thanku sir

[@MikeEnergy_]

Nice

[@aliyajamal3757]

Thanks

[@LJY619]

tq very much

[@monikamonika3225]

Spectroscopy ma different hota h ya same organic type

[@wordswilllive1273]

same question: why trans coupling constant is higher than cis coupling constant

[@teyrasiridae4704]

shivangi verma you’ll want to look up the Karplus relationship, which shows that if the dihedral angle is close to 0 or 180 degrees, coupling is the strongest. If the dihedral angle is 90 degrees, coupling is almost 0 Hz

[@destinylife467]

sir non first order spectra

[@user-rp6gl4vb7p]

thanks