NMR spectrum??????

[busdent]

---

Members don't see this ad.

can somebody help me explain some basics of NMR spectrum..i have read it so many times and I don't understand it.

 

[Manyak222]

just know that each peak represents either a single proton or a group of equivalent protons

the areas under each peak shows the ratio of non equivalent hydrogen groups in a molecule.

Since NMR measures NUCLEI, there is less interference when the electron density around a proton is withdrawn from an electronegative atom or group, and will show up downfield (to the left) of the spectrum. thus a H next to a Cl will show up downfield to a proton next to a methyl group.

I dont wanna go into splitting...

can somebody help me explain some basics of NMR spectrum..i have read it so many times and I don't understand it.

 

[alex1231]

How do you figure out if you have a proton with different chemical environment in the molecule?
If the molecule is symmetrical you have ptotons in the same chemical environment. Is that right?

 

[Decan]

Let's say you have propane...CH3CH2CH3. Because of symmetry, the two methyl groups are equivalent. To figure out splitting, focus on a carbon and follow the n+1 rule, where n is the number of neighboring hydrogens. For example, carbon 1 of methane is is adjacent to a carbon with 2 protons. That group will show a triplet (2+1=3 peaks). Carbon 2 is influenced by 6 protons (3 from each of the neighboring carbons) so it will produce a spetet (again n=6 so 6+1=7). The final methyl group will also produce a triplet (for the same reason as carbon 1) but since both the methyl groups are equivalent, they will simply overlap with each other. For this reason, your NMR should have a septet and a triplet.

This is a simple case...I recommend you do some practice problems from your text. Hope that helps!