Proton NMR, not on adjacent carbons dont split? plz help

[smiley00]

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So, I was under the impression that protons upto 3 bonds away can split each other, unless they are equivalent.

"Interaction between two nuclei occurs through chemical bonds, and can typically be seen up to three bonds away." (got this exactly from wikipedia)

But I just got a question wrong from one of my practice problems. The question is about splitting of propyne. The answer states there will be 2 singlets, bc the diff protons are not adjacent carbons. 😕

Although, this is true, they are still on the next carbon over? I thought it would be a doublet and a quartet.

Now, I m thinking it would be singlets bc the propyne has 3 bonds + 1 bond so really its 4 bonds away? Is that right? or is this question incorrect?

Thank you!! 🙂

 

[lutopie0730]

"Interaction between two nuclei occurs through chemical bonds, and can typically be seen up to three bonds away." (got this exactly from wikipedia)

I think this is talking about chemical shifts, not splitting.

For example, for -O-CH2-CH3, the proton at the end will be deshielded slightly because of oxygen which is three bonds away.

 

[yappers2009]

The reason why it is not a doublet and quartet is because there are no adjacent carbons containing hydrogens for both carbons that do have hydrogens. Therefore it would be 2 singlets because they are different types of carbons. If there were 2 double bonds, then there would be 1 peak that is doubled in intensity because they are the same. (n+1 rule; there will be n+1 peaks for each adjacent hydrogen)

Chemical shift can be for 3 away, but splitting must be adjacent.

 

[smiley00]

Ohhh Got it! Thank you to both of you! 🙂