[lohjxMARCUS]

Hi i was given this question and worked it out, i've attached images below. But i just cant figure out why the Signal at 1.55ppm is a septet.

According to the complex spin spin coupling laws  H2 and H4 are different non equivalent protons, thus it splits into a triplets of quartet. If H2 and H4 were equivalent then i would understand it would be a septet. But why is the diagram a septet? Can anyone enlighten me please??

Question:



My Solution:



Mod edit: img tags added. Please use img tags like this: [img]http://image uri[/img] or upload images as attachments (click the "Additional Options..." tab below the edit field in the reply window) or use SMILES code - please do not link to external image hosting websites. For more information on formatting posts correctly, click here. Dan

[discodermolide]

5 neighbours = 6 lines which is what you have.
The protons are equivalent as there is free rotation about the bonds.

[lohjxMARCUS]

5 neighbours = 6 lines which is what you have.
The protons are equivalent as there is free rotation about the bonds.

Ok, i understood that however but i have another question; Hd is split by He and Hc to give doublets of triplet, and Hc is split by Hd and Hb to give triplets of quintets.

In this question there are no pi bonds so why are Hd and Hc paired like that?

(correct picture)


Sorry i uploaded the wrong picture, its correct now.

Mod edit: img tags added. Please use img tags like this: [img]http://image uri[/img] or upload images as attachments (click the "Additional Options..." tab below the edit field in the reply window) or use SMILES code - please do not link to external image hosting websites. For more information on formatting posts correctly, click here. Dan

[lohjxMARCUS]

I uploaded the wrong picture in the post above, i edited it and its correct now. sorry 

[Arkcon]

You can also attach images to your posts here.  Its under Additional Options:

[discodermolide]

These are the theoretical splitting patterns for the individual protons, you will only observe that if the spectrum is first order. and the J values are much larger.