OChem- Improving NMR

[Pinkswan]

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I've gotten more comfortable with NMR since the last test in that I can solve beginner level problems. Now I need to master more intermediate level problems before our next test. While we get partial credit for attempting and figuring certain NMR fragments, I feel that getting the NMR completely right would easily have gotten me 20 more points on my test. Anyone have suggestions fir mastery of NMR?

 

[RinShanKaiHo]

The greater extent electrons are pulled away from the tested atom(H for H NMR, C for C NMR, etc) by functional groups such as an alcohol, aldehyde, etc. (You need to remember or deduce from the electronegativity) , the more "delocalised" the electrons are, and the higher the chemical shift is.

Basically orgo is about where electrons want to reside. If you understand this fully, orgo is super easy.

 

[rg2o3]

I did very well in Orgo 1 and 2, but I HATED NMR. I am not sure why, it just didn't sit well with me. With that being said, I had to practice A LOT. I mainly just searched google for practice NMR problems and did a few every day in the couple weeks leading up to the exam that had NMR on it. Good luck!

 

[DelayedGratification]

Do you get IR in addition to NMR?
You just need to be able to identify functional groups, as well as understand shielding and how it relates to chemical shifts. NMR just takes practice

 

[Robin-jay]

Memorize common bondings and their chemical shifts.

Then practice, practice, practice.

Sincerely, someone with a masters degree where these were relevant.

 

[rg2o3]

Memorize common bondings and their chemical shifts.

Then practice, practice, practice.

Sincerely, someone with a masters degree where these were relevant.

God bless you. If I had to take one more Chemistry, I would have not made it lol. I did very well in my courses, but it hurt every second, lol. I needed one more Chemistry to get a minor in it and just couldn't get myself to do it.

 

[Pinkswan]

I did very well in Orgo 1 and 2, but I HATED NMR. I am not sure why, it just didn't sit well with me. With that being said, I had to practice A LOT. I mainly just searched google for practice NMR problems and did a few every day in the couple weeks leading up to the exam that had NMR on it. Good luck!

Do you get IR in addition to NMR?
You just need to be able to identify functional groups, as well as understand shielding and how it relates to chemical shifts. NMR just takes practice

On the site I practice on, some problems have IR while some don't. But we are expected to use IR as well on the actual test, and frankly using the IR makes the problem a bit easier. Having a C NMR kinda suffices when there isn't a IR to identify groups like carbonyls, ethers, or alkynes. And yea ik most of the major signals. I think some of the toughest parts is splitting when it comes to benzenes or other electronegative atoms, as the splitting shows up as this weird mix, making it tough for me to predict a fragment's location. (I hope I'm making sense lol)

 

[Robin-jay]

On the site I practice on, some problems have IR while some don't. But we are expected to use IR as well on the actual test, and frankly using the IR makes the problem a bit easier. Having a C NMR kinda suffices when there isn't a IR to identify groups like carbonyls, ethers, or alkynes. And yea ik most of the major signals. I think some of the toughest parts is splitting when it comes to benzenes or other electronegative atoms, as the splitting shows up as this weird mix, making it tough for me to predict a fragment's location. (I hope I'm making sense lol)

You can look up how para, ortho, meta positions influence chemical shift. Aromatic shifts aren't so bad, most are 7-8 ppm.

When I taught organic chemistry lab courses, it was generally pretty hard to explain chemical shifts to students.

The way to do it is to practice until you get stuck, then ask someone more skilled in the subject where you're stuck at.

 

[Pinkswan]

You can look up how para, ortho, meta positions influence chemical shift. Aromatic shifts aren't so bad, most are 7-8 ppm.

When I taught organic chemistry lab courses, it was generally pretty hard to explain chemical shifts to students.

The way to do it is to practice until you get stuck, then ask someone more skilled in the subject where you're stuck at.

Oh yea ik to expect protons on an aromatic in 6.5-8 ppm range. I mean like the way the splitting of the signal works, especially when an electronegative atom like Br is present. The splitting sometimes forms this unclear mix that makes it hard to tell how many neighboring protons are really present. But thanks! I'll just continue practicing and look back at the ones I missed to maybe figure some more strategies.

 

[Yhorm the Giant]

NMR and IR was hands down my favorite part of ochem. Don't know why. I loved it. The book ochem as a second language was helpful, and honestly I just one day watched like 7 straight hours of YouTube videos on it from several different teaching sites and after seeing such a variety of examples it just completely clicked into place. Of course I was pausing videos in trying to figure stuff out before I got the answers were shown to actively learn instead of passive learning, but really it was just practice and then it clicks. Before that it just seems really abstract and you just got to get over that hump

 

[Thor123422]

NMR is pretty straightforward.

Just know...

that chemically equivilant hydrogens (just look at symmetry / rotations) will be the same peak.

The N+1 rule

The area under a specific peak gives you the number of hydrogens involved.

And that less electrons around an atom gives a greater downfield shift (greater ppm).

Maybe also memorize the tables of NMR functional groups depending on what your professor is like. Mine (now my current research adviser) told us that there's no scenario you won't have a chart to reference, and the charts are just a ball park to look at regardless, so he gave us a table.

 

[Robin-jay]

Honestly, I would watch Khan academy videos regarding H-NMR, then do as many practice problems as you can.

Whenever you get stuck, write down what you don't understand. Go to professor for help.

When you go to professor for help, get a feel for what he's going to expect on exams.

This is how many students earn A's.

 

[Magus5454]

I honestly felt NMR IR etc was the easiest part of organic. It just made sense to me.

 

[workaholic181]

My professor gave us this site and it helped me immeasurably when I was in orgo 2. https://www3.nd.edu/~smithgrp/structure/workbook.html

 

[Medic741]

Thank god orgo is over!! Will feel so good when you can look back on this from med school 😉

 

[Robin-jay]

Thank god orgo is over!! Will feel so good when you can look back on this from med school 😉

You guys are crazy.

Orgo >>>>>>> all other pre-reqs.

 

[Pinkswan]

You guys are crazy.

Orgo >>>>>>> all other pre-reqs.

I'll admit orgo may be harder than other prereqs yet it's more interesting as well

 

[Pinkswan]

My professor gave us this site and it helped me immeasurably when I was in orgo 2. https://www3.nd.edu/~smithgrp/structure/workbook.html

Am definitely looking for more challenging problems as I get the easier ones right! Thank you so much for this!

 

[Robin-jay]

I'll admit orgo may be harder than other prereqs yet it's more interesting as well

I thought it was the easiest, and most "fun".