1H NMR spectrum

[nhasifuture]

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can someone please explain why the 1H NMR spectrum of m-xylene shows 4 peaks: 2s singlets, 1 doublet, and 1 triplet. Thanks!

 

[PooyaH]

I'm gonna try my best to expalin this. Look at the attached picture of m-xylene and give each carbon on the ring a number. Start from the carbon on the top that has a methyl attached which would be carbon #1 then go clockwise...Anyways, both CH3's show a singlet and the hydrogen on carbon #2 shows a singlet also. Carbon #4 and #6 both show doublet and carbon #5 shows a triplet...Hope it makes sense!

 

[nhasifuture]

thanks, but i still dont see how carbon#6 shows a doublet and there is only 1 doublet on the answer. I thought C#6 would show a singlet.

 

[nhasifuture]

oops, never mind I think i got it! Thanks again for a quick response.

 

[PooyaH]

Just know the n+1 rule where n is the number of hydrogens attached to the adjacent carbon atam...this makes things easy!

 

[klutzy1987]

There is one Hydrogen on the carbon next to the 6 position. If its neighboring carbons have one H then n+1 is 2, two peaks or a doublet.

 

[Deontologist]

I'm gonna try my best to expalin this. Look at the attached picture of m-xylene and give each carbon on the ring a number. Start from the carbon on the top that has a methyl attached which would be carbon #1 then go clockwise...Anyways, both CH3's show a singlet and the hydrogen on carbon #2 shows a singlet also. Carbon #4 and #6 both show doublet and carbon #5 shows a triplet...Hope it makes sense!

What about Carbon # 3, I would expect it to be a sextet...or am I wrong.....??

 

[PooyaH]

Carbon #3 doesn't have any hydrogens!

 

[Deontologist]

Carbon #3 doesn't have any hydrogens!

oh...So N+1 applies only when there is at least a single Hydrogen present...not otherwise..!!
That clears it up for ......Thanks......!!

I would be really looking for carbon 1 and 3 in NMR, if you hadn't enlightened me...lol...Thanks again..!!

 

[PooyaH]

oh...So N+1 applies only when there is at least a single Hydrogen present...not otherwise..!!
That clears it up for ......Thanks......!!

I would be really looking for carbon 1 and 3 in NMR, if you hadn't enlightened me...lol...Thanks again..!!

Yeah make sure you look for Carbon 1 and 3 in 13C NMR but not 1H NMR 😀

 

[Deontologist]

Yeah make sure you look for Carbon 1 and 3 in 13C NMR but not 1H NMR 😀

Do we need to know 13C NMR for DATs....??

 

[PooyaH]

Do we need to know 13C NMR for DATs....??

Indeed

 

[AndyK]

http://forums.studentdoctor.net/showthread.php?t=535689

 

[drgreen]

To find peak character, use the formula n+1 where n=number of adjacent H's

RED H's: Split by 0 h's on adjacent carbon (0+1=1 Singlet)
GREEN H: Split by 0 h's on adjacent carbon (0+1=1 Singlet)
BLUE H's: Split by 1 adjacent grey H (1+1=2 doublet)
GREY H: Split by 2 adjacent blue H (2+1=3 triplet)

 

[atlanta213]

RED H's: Split by 0 h's on adjacent carbon -doublet
GREEN H: Split by 0 h's on adjacent carbon -sept ( 7)
BLUE H's: Split by 1 adjacent grey H (1+1=2 doublet)
GREY H: Split by 2 adjacent blue H (2+1=3 triplet

Which part i missed?

 

[PooyaH]

RED H's: Split by 0 h's on adjacent carbon -doublet
GREEN H: Split by 0 h's on adjacent carbon -sept ( 7)
BLUE H's: Split by 1 adjacent grey H (1+1=2 doublet)
GREY H: Split by 2 adjacent blue H (2+1=3 triplet

Which part i missed?

For the red one: there are no hydrogens on the adjacent carbon atoms so you only get a singlet!
For the green one: same thing as the red one! there are no hydrogens on number 1 and 3 carbons!

 

[Lazerous]

Which singlet peak would be more downfield, the red one or green?

 

[klutzy1987]

Which singlet peak would be more downfield, the red one or green?

The green by a drop i think.