NMR coupling pattern for hydrocarbon

[![enter image description here](https://i.stack.imgur.com/91sXA.jpg)](https://i.stack.imgur.com/91sXA.jpg)


What does the 1H NMR spectroscopy coupling pattern look like for the hydrogen attached to the carbon that the blue arrow is pointing to? There is a $\ce{CH2}$ attached to ether side of the carbon, but each of those carbons is in a different chemical environment from the other. Does that mean that it is a doublet of doublets? Or just a doublet?




The two $\ce{CH2}$ groups are, as you mentioned, in chemically different environments. Thus, each one will couple separately. But within each of the two groups, there are *two* protons. So you will not get a doublet of doublets, but a *triplet* of *triplets.*


Note that for each $\ce{CH2}$ group the hydrogens are *chemically* equivalent but not *magnetically.* Therefore, if you include a chiral environment, the pattern will further complexify itself into a higher-order signal that cannot easily be analysed. But since you’re probably measuring in chloroform you need not worry — there is no chiral information present and the couplings will be degenerate.


If I had to label a spin system here, I would probably choose $\ce{A3BB'CC'MM'X3}$.


By the way, it can be assumed that both coupling constants to the two different $\ce{CH2}$ groups be reasonably similar that the overall pattern *looks like* a quintet without actually being one.


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