[kazeAaqib]

(OH)CH2C(CH3)2CH2CH

the question is deduce the structured formula of a molecule with a triplet, quartet, singlet, singlet and singlet that showed relative intensities of 2:3:6:2:1 respectively on a proton nmr spectrum. I figured that this is the only molecule it could be.

I have pretty much identified the peaks but am not sure. The dimethyl, c(ch3)(ch3) is obviously the singlet with intensity 6 because it is the only environmental with 6 protons however how is it a singlet, I thought it would have been a quartet because it's neighbouring environment has 3 Hydrogens.

Also how do the peaks arise can both the environments either side influence the spin and the peak on a nmr spectrum and how do you know which protons will influence particular environments.

[Schrödinger]

(OH)CH2C(CH3)2CH2CH

the question is deduce the structured formula of a molecule with a triplet, quartet, singlet, singlet and singlet that showed relative intensities of 2:3:6:2:1 respectively on a proton nmr spectrum. I figured that this is the only molecule it could be.

2,2-dimethylbutan-2-ol fits the bill perfectly.
Were you given prior data regarding the double bond equivalent, molecular mass or functional groups present?

I have pretty much identified the peaks but am not sure. The dimethyl, c(ch3)(ch3) is obviously the singlet with intensity 6 because it is the only environmental with 6 protons however how is it a singlet, I thought it would have been a quartet because it's neighbouring environment has 3 Hydrogens.

Also how do the peaks arise can both the environments either side influence the spin and the peak on a nmr spectrum and how do you know which protons will influence particular environments.

I was told that when it comes down to H-NMR, we can expect a proton to affect another if the distance between them is less than 3 bonds.

example : H-C-C-H. The distance between the hydrogens is 3 bonds
Something to do with coupling constants, I presume...

[kazeAaqib]

Hi
thanks and no we were onlY given the nmr data that I've given.

2,2-dimethylbutan-2-ol then the OH group would be bonded on one of the methyl groups, that would fit however would that make two peaks on the second carbon and create that environment to have 5 hydrogens CH3CH2 and another with OH but there are only 2:3:6:2:1 peaks available.

[Schrödinger]

Sorry... That was a typo 
I meant 2,2-dimethylbutan-1-ol. 
Sorry once again

[kazeAaqib]

thats fine

could briefly explain how the three singlet arise from this molecule

[Schrödinger]

The H attached to O produces a singlet. This is always the case with OH, because it is treated to be in a completely different environment of it's own. And since there is only one such proton, the intensity is, let's say, k.

The 2 methyl groups on the 2nd Carbon atom also produce a singlet, because they are attached to a quaternary carbon (i.e., C2 is quaternary). Since there are 6 such Hydrogens, the intensity is 6k.

The hydrogens attached to C1 also produce a singlet, because, on one side C1 is attached to O-H which can be neglected due to it's completely different electronic environment, and on the other side it is attached to a quaternary Carbon (C2) and the intensity is 2k, since there are 2 such hydrogens

The rest should be easy, use the 2n + 1 rule. (ofcourse, n = 1/2 here)

Please feel free to ask more questions if you are not comfortable with my explanation.

[kazeAaqib]

why is there a triplet and quartet having 2H and 3H respectively when their carbon atoms their next to them have 2H and 3H using the n+1 rule. It doesnt make any sense CH2CH3.

[Schrödinger]

For 2,2-dimethylbutan-1-ol, it is :

triplet, quartet, singlet, singlet, singlet in the ratio 3:2:6:2:1

[kazeAaqib]

Thanks