Carbon nmr

[sam0001]

How many carbon environments in heptane?

[sam0001]

And in methyl benzene?

[thushan]

4 and 5.

[sam0001]

So does that mean methyl benzene should produce 5 peaks?

Cause the spectum shows two.

[sam0001]

In hnmr that is

[thushan]

So does that mean methyl benzene should produce 5 peaks?

Cause the spectum shows two.

Yeah, with aromatic compounds (containing benzene) - yes methylbenzene should have 4 peaks, but three of the peaks merge into each other as they are all H atoms bonded to benzene. Something weird happens between H atoms bonded to benzene and you have a massive blob at around 7-8 ppm which is those three peaks merged into each other.

[sam0001]

Ah okay, thanks! Do we need to know much about NMR and benzene? Or canwe just apply the normal rules and assume there's 5 peaks?

[thushan]

Ah okay, thanks! Do we need to know much about NMR and benzene? Or canwe just apply the normal rules and assume there's 5 peaks?

Nah. There are 4 H peaks, its just that three of them are so close to one another that they 'merge.'

[Mao]

Ah okay, thanks! Do we need to know much about NMR and benzene? Or canwe just apply the normal rules and assume there's 5 peaks?

Nah. There are 4 H peaks, its just that three of them are so close to one another that they 'merge.'

And thus we have the first example of a 'multiplet'.

[jadams]

Do we have to worry about NMR environments or naming for benzene/benzene derivatives for VCE Chem?

[Mao]

Do we have to worry about NMR environments or naming for benzene/benzene derivatives for VCE Chem?

environments, yes.
naming, no.

[thushan]

Do we have to worry about NMR environments or naming for benzene/benzene derivatives for VCE Chem?

environments, yes.
naming, no.

If VCAA gives an NMR question on benzene and its derivatives...someone's f**ked.
*MUST TEACH STUDENTS BENZENE ANALYSIS*

[jadams]

If VCAA gives an NMR question on benzene and its derivatives...someone's f**ked.
*MUST TEACH STUDENTS BENZENE ANALYSIS*

*MUST TEACH SELF BENZENE ANALYSIS*

[Mao]

Here, have some aromatic practice.

I have somewhat systematically named the compounds, the answers are in the filenames, given as the number of aromatic carbons in each environment.

e.g. for monosubstituted benzene (such as phenol), the answer is given as 1-2-2-1.

See attached.

[Mao]

If you want super challenge:



The answer is 6 carbon environments, ratio is 2 (methyl), 2 (quaternary carbon caps attached to methyl), 1 (secondary carbon R-C-R bridge in between the q-carbon caps), 4 (s-carbon R-C-R bridge) 2 (the other two tert-carbon caps), 1 (s-carbon R-C-R bridge at the other end)

If you are feeling even more adventurous, try getting the environments here:

http://upload.wikimedia.org/wikipedia/commons/0/0b/Addition_of_O_atom_into_C60_Scheme.png
fuck that.