How many H NMR Peaks?

[wired202808]

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Ok so the answer is Two Singlets.

Im confused, I can see that this is symmetrical all around and the Methyls would give 1 signal total, meanwhile the green carbons have at least 1 H, so wouldnt that be a doublet?

I picked one singlet and one doublet as the answer. Im just confused why its Two Singlets.

 

[Sisero68]

like will not recognize like.

the aromatic H do to a mirror has the same energy/frequency as the neighboring aromatic H on the same side and will not recognize it.

 

[wired202808]

like will not recognize like.

the aromatic H do to a mirror has the same energy/frequency as the neighboring aromatic H on the same side and will not recognize it.

ok so then what constitutes 2 singlets? wont the methyl's be the same as the the other hydrogen's and only give rise to 1 singlet?

 

[Sisero68]

CH3, CH3 = 1 singlet
aromatic H, H, H, H both sides = 1 singlet

 

[wired202808]

CH3, CH3 = 1 singlet
aromatic H, H, H, H both sides = 1 singlet

but the carbon right below the H, has one other H on it so wouldnt this be considered a doublet? due to the N+1 rule?

 

[AlbinoPolarBear]

Identical hydrogens WILL NOT couple to each other.

The aromatic hydrogens (in green) are identical due to symmetry and will NOT couple to each other, producing singlets at the same frequency. You will see just 1 singlet with a integration of 4 for the 4 hydrogens.

 

[wired202808]

Identical hydrogens WILL NOT couple to each other.

The aromatic hydrogens (in green) are identical due to symmetry and will NOT couple to each other, producing singlets at the same frequency. You will see just 1 singlet with a integration of 4 for the 4 hydrogens.

ok understood I assumed that I as I pinged you just wanted to make sure so really equivalent H's would be singlets Unless they were attached to something else that produced another peak? meaning another structure NOT a benzene? right. I see one from chad's notes.

 

[Sisero68]

also make sure you realize that the carbon with the CH3 attached also has a double bond to it so there is no H there...

 

[wired202808]

also make sure you realize that the carbon with the CH3 attached also has a double bond to it so there is no H there...

no i knew that I just wasnt sure about its neighbor but it makes sense since their all equivalent that equivalent H's do not split each other and since 4 of them are equivalent it only gets counted as a singlet.

Thanks for the help fellas.