HNMR

[Jazz_Blue]

1) How many Hydrogen environments are there in Propanol? Can someone explain to me please?

2) In high resolution proton NMR, how many splitting are there for propanol? how many will CH2 split? ( since there is a CH3 and also CH2 and OH next to it)

[pi]

Assuming 1-Propanol

1) 4 environments, basically, the each H attached to a different carbon is in it's own environment (so that's 3 environments) and then the H in the -OH is in it's own environment too, so 4 in total

2) There will be four environments: 3 peaks (-CH3), 6 peaks (the CH2 in the middle), 3 peaks (the CH2 connected with the OH) and 1 peak (the H from the OH)


I think that's right :S (my chem is very very rusty)

[thushan]

Depends on which propanol it is -

Propan-1-ol: 4 proton environments, a singlet (OH), a triplet (carbon-1), a triplet of a quartet (a 12-et) (carbon-2) [multiplicity rule, not sure whether you have to know it], and a triplet (carbon-3)

Propan-2-ol: 3 Proton environments, a singlet (OH), a doublet (carbons 1 and 3), and a septet (carbon 2).

[pi]

I gave the VCE response not taking into account multiplicity btw

[Ravit]

So according to the vce reponse would 6 peaks for the CH2 in the middle be correct for propan-1-ol?

[pi]

I don't think they'd ask you a question where multiplicity was an option (they rarely ask you to draw high res HNMRs anyway though I think). But if they did, when I was in VCE I would have drawn 6 peaks, because that's what's in the course (to my knowledge).

[thushan]

I gave the VCE response not taking into account multiplicity btw

Not sure what the VCE response is actually...because some schools actually do teach the multiplicity rule, my school and Pascoe Vale Girls' College (where I gave a talk last week).

[pi]

I gave the VCE response not taking into account multiplicity btw

Not sure what the VCE response is actually...because some schools actually do teach the multiplicity rule, my school and Pascoe Vale Girls' College (where I gave a talk last week).

I just assumed as MHS didn't teach it and Heinemann didn't mention it at all (and neither did A+ study notes or TSFX notes) that it wasn't on the course

As said before, I doubt VCAA would give an example like that to draw.

[thushan]

I gave the VCE response not taking into account multiplicity btw

Not sure what the VCE response is actually...because some schools actually do teach the multiplicity rule, my school and Pascoe Vale Girls' College (where I gave a talk last week).

I just assumed as MHS didn't teach it and Heinemann didn't mention it at all (and neither did A+ study notes or TSFX notes) that it wasn't on the course

As said before, I doubt VCAA would give an example like that to draw.

Yeah I doubt that too.

[Ravit]

Cheers guys thanks for clearing that up

[charmanderp]

According to the Access lecture, which was conducted by the chief examiner, you need to account for multiplets. It was about the only useful piece of information I gleaned that entire night.

[Teen]

Guys . It might sound stupid.seriously wat is multiples. Is it when u have a complex splitting .

[thushan]

According to the Access lecture, which was conducted by the chief examiner, you need to account for multiplets. It was about the only useful piece of information I gleaned that entire night.

Chris Dwyer mentioned that multiplicity rule is needed? FUQ. I stand corrected.
Are you sure? This is important because I made sure all my NMR qns in my book had no multiplicity issues.

[thushan]

Guys . It might sound stupid.seriously wat is multiples. Is it when u have a complex splitting .

yup! its when you have two neighbouring carbons that are in different environments.

[Teen]

Thanks thushan