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s.aureus
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In Hnmr, when the question asks us for the splitting pattern of the adjacent carbons, how do we know which adjacent carbon to look at when there are more than two carbons in the molecule??????????

For example in CH3CH2CH2CH3

if it asks us for the splitting pattern of the CH2 carbon, how do we know which carbon to look at, is it a triplet or quartet??

Please help
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charco
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(Original post by s.aureus)
In Hnmr, when the question asks us for the splitting pattern of the adjacent carbons, how do we know which adjacent carbon to look at when there are more than two carbons in the molecule??????????

For example in CH3CH2CH2CH3

if it asks us for the splitting pattern of the CH2 carbon, how do we know which carbon to look at, is it a triplet or quartet??

Please help
You have to look at all of the adjacent hydrogen atoms. Only non-equivalent hydrogens can split.

In the example above there are two environments only, CH3CH2, the next CH2 is identical to the first and the next CH3 is identical to the first.

So you have a triplet and a quartet, whse intensities (integrals) are in the ratio of 3 to 2
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s.aureus
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(Original post by charco)
You have to look at all of the adjacent hydrogen atoms. Only non-equivalent hydrogens can split.

In the example above there are two environments only, CH3CH2, the next CH2 is identical to the first and the next CH3 is identical to the first.

So you have a triplet and a quartet, whse intensities (integrals) are in the ratio of 3 to 2
Okay thanks, but what if they ask for example, what is the splitting pattern of CH2, from CH3CH2CH2CH3, then is it a triplet or a quartet?? This what i mean when i say which adjacent carbon do we look at
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charco
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(Original post by s.aureus)
Okay thanks, but what if they ask for example, what is the splitting pattern of CH2, from CH3CH2CH2CH3, then is it a triplet or a quartet?? This what i mean when i say which adjacent carbon do we look at
You look at both, but the CH2 is equivalent, and therefore doesn't affect it, therefore the CH3 changes the CH2 into a quartet.
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s.aureus
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(Original post by charco)
You look at both, but the CH2 is equivalent, and therefore doesn't affect it, therefore the CH3 changes the CH2 into a quartet.
So your saying if there are the same CH groups next to each other, so the CH2CH2, then it won't split ?? For example does ethane, CH3CH3, not have a splitting pattern because CH3s are equivalent??
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charco
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(Original post by s.aureus)
So your saying if there are the same CH groups next to each other, so the CH2CH2, then it won't split ?? For example does ethane, CH3CH3, not have a splitting pattern because CH3s are equivalent??
Correct
Equivalent protons cannot split one another.

Ethane has one singlet.

Name:  ethane_nmr.jpg
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s.aureus
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(Original post by charco)
Correct
Equivalent protons cannot split one another.

Ethane has one singlet.

Name:  ethane_nmr.jpg
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Hi okay, sorry im confused again, i get this but if you apply this to CH3CH2CH2CH3, shouldn't you have one quartet and one singlet then? Because CH2CH2 are equivalent and can't split each other
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charco
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(Original post by s.aureus)
Hi okay, sorry im confused again, i get this but if you apply this to CH3CH2CH2CH3, shouldn't you have one quartet and one singlet then? Because CH2CH2 are equivalent and can't split each other
The CH2 protons get split into a quartet by the adjacent CH3 protons
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s.aureus
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(Original post by charco)
The CH2 protons get split into a quartet by the adjacent CH3 protons
Riiiiiiiight okay, in your first explanation you said there's triplet and quartet in the ratio of 3:2, I understand where the two is from as there are two quartets from both CH2s, but where did the three on the triplets come from??, as there are only 2 CH3, and you said the CH2 wont initiate a split as it is equivalent
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charco
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(Original post by s.aureus)
Riiiiiiiight okay, in your first explanation you said there's triplet and quartet in the ratio of 3:2, I understand where the two is from as there are two quartets from both CH2s, but where did the three on the triplets come from??, as there are only 2 CH3, and you said the CH2 wont initiate a split as it is equivalent
CH3 has three hydrogen atoms - this is where the three comes from
It is split into a triplet by the adjacent CH2 hydrogen atoms (n+1 rule)
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