H NMR questions..

[potbelly]

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Hi all,

In Destoryer OCHEM #185, since there's a symmetry, the splitting pattern for central proton is singlet ratehr than triplet.

Then here's my question.

If you look at propane, 1,2 dibromopropane, or butane, shouldn't central protons be all singlet? However, they are septet, quintet, or heptet respectively.
I think all these three compounds have symmetry somewhat.

Could someone explain this?

Thanks in advance.

 

[Jongho Yoon]

Hi all,

In Destoryer OCHEM #185, since there's a symmetry, the splitting pattern for central proton is singlet ratehr than triplet.

Then here's my question.

If you look at propane, 1,2 dibromopropane, or butane, shouldn't central protons be all singlet? However, they are septet, quintet, or heptet respectively.
I think all these three compounds have symmetry somewhat.

Could someone explain this?

Thanks in advance.

I think since the chemical environment of the central proton is different from those on each side, those protons should be counted.

For propane, central proton's environment is different from those on each side (2protons+2methyl group attached to central carbon vs 3 protons+1methyl group attached to side carbons), even though those protons on each side have the same chemical environment.