universalcj
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4-hydroxybutanoic

anyone who can anaylyze this with high resolution proton nmr

the mark scheme says
two singlets, two triplets and one quintet.

why
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Hellllpppp
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It’s difficult to explain with words so I’ve attached a diagram I’ve drawn quickly.
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scimus63
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HO-CH2-CH2-CH2COOH
There are 5 proton environments in this molecule. The -COOH and -OH will both give singlets
HO-CH2 the CH2 group (methylene group) will couple with the next -CH2 group and split to a triple.
-CH2COOH the -CH2 protons here will couple with the -CH2 group in the middle to give a triplet
-CH2-CH2-CH2 the protons in the middle -CH2 group can couple with both the neighboring protons on the -CH2 groups to give the quintet
the -OH and COOH protons do not couple and you will see no splitting, so singlets only here.
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universalcj
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(Original post by scimus63)
HO-CH2-CH2-CH2COOH
There are 5 proton environments in this molecule. The -COOH and -OH will both give singlets
HO-CH2 the CH2 group (methylene group) will couple with the next -CH2 group and split to a triple.
-CH2COOH the -CH2 protons here will couple with the -CH2 group in the middle to give a triplet
-CH2-CH2-CH2 the protons in the middle -CH2 group can couple with both the neighboring protons on the -CH2 groups to give the quintet
the -OH and COOH protons do not couple and you will see no splitting, so singlets only here.
thank you that's the point I got confused
I thought I only take account for the hydrogen attached into carbon atoms....
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