Orgo question from Topscore 2

[Djapprentice]

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74) The proton NMR spectrum of m-xylene will show

(Since I can't get the picture for it, the structure of m-xylene for those who don't know, is a methyl group on benzene & another methyl meta to the first methyl group)

A) 4 peaks: 2 singlets, 1 doublet, & 1 triplet
B) 5 peaks: 2 singlets, & 3 triplets
C) 6 peaks: 3 singlets & 3 triplets
D) 5 peaks: 1 singlet, 2 doublets, & 2 triplet
E) 5 peaks: 1 singlet, 3 triplets, & a quartet

I was able to pick the correct ans choice A) based on the first half of the ans (the 4 peaks) becuase I know there's 4 different environments. The thing that has me confused are the 2 singlets, 1 doublet & 1 triplet, I think its the H = n + 1 equation right, please help clarify the multiplets part further, thanks a lot in advance

Anybody, I'll really appreciate the help, my test is on the 23rd

 

[Djapprentice]

74) The proton NMR spectrum of m-xylene will show

(Since I can't get the picture for it, the structure of m-xylene for those who don't know, is a methyl group on benzene & another methyl meta to the first methyl group)

A) 4 peaks: 2 singlets, 1 doublet, & 1 triplet
B) 5 peaks: 2 singlets, & 3 triplets
C) 6 peaks: 3 singlets & 3 triplets
D) 5 peaks: 1 singlet, 2 doublets, & 2 triplet
E) 5 peaks: 1 singlet, 3 triplets, & a quartet

I was able to pick the correct ans choice A) based on the first half of the ans (the 4 peaks) becuase I know there's 4 different environments. The thing that has me confused are the 2 singlets, 1 doublet & 1 triplet, I think its the H = n + 1 equation right, please help clarify the multiplets part further, thanks a lot in advance

Anybody, I'll really appreciate the help, my test is on the 23rd

Anybody, I'll really appreciate the help, my test is on the 23rd

 

[artmed12]

ok here goes:

4 types of hydrogen:
6 H's on the methyl groups are all equiv
1 H inbetween the methyl groups
1 H PARA to the last one i listed
2 H's ORTHO to the last one i listed

you get the first singlet: from the H's on the methyl groups. These are all equivalent and they show no splitting because they have no neigboring H's on any carbon 1 bond away in any direction.

Second singlet: from the H that is inbetween the two meta methyl groups. This hydrogen also has no neigboring H's on any carbons one bond away.

1 Triplet: from the hydrogen PARA to the last one we spoke about. THis Hydrogen has 1 Hydrogen as a neigbor 1 bond away on 2 directions. It has two neighboring H's, Therefore it has a triplet. (Neighboring H's +1 = # of peaks).

1 Doublet: from the 2 H's ORTHO to the last one. These are both equivalent and they both have the 1 neighboring Hydrogen. (1 neighboring H +1 = 2 peaks).

Damm its tough to explain that without a picture. I hope you could follow that.

peace out

 

[Djapprentice]

ok here goes:

4 types of hydrogen:
6 H's on the methyl groups are all equiv
1 H inbetween the methyl groups
1 H PARA to the last one i listed
2 H's ORTHO to the last one i listed

you get the first singlet: from the H's on the methyl groups. These are all equivalent and they show no splitting because they have no neigboring H's on any carbon 1 bond away in any direction.

Second singlet: from the H that is inbetween the two meta methyl groups. This hydrogen also has no neigboring H's on any carbons one bond away.

1 Triplet: from the hydrogen PARA to the last one we spoke about. THis Hydrogen has 1 Hydrogen as a neigbor 1 bond away on 2 directions. It has two neighboring H's, Therefore it has a triplet. (Neighboring H's +1 = # of peaks).

1 Doublet: from the 2 H's ORTHO to the last one. These are both equivalent and they both have the 1 neighboring Hydrogen. (1 neighboring H +1 = 2 peaks).

Damm its tough to explain that without a picture. I hope you could follow that.

peace out

Hey Artmed, thanks a million & 3 1/4, I really appreciate it, very well explained, & the way you explained it made so much sense now, thanks you so much again, if you need help with anything let me know.

 

[Euphoria36]

ok here goes:


1 Doublet: from the 2 H's ORTHO to the last one. These are both equivalent and they both have the 1 neighboring Hydrogen. (1 neighboring H +1 = 2 peaks).

a quick follow up question:

to see if I am understanding this correctly, there's only one doublet b/c the 2 "ortho" Hs are equivalent right?

thanks for explaining this in such detail! 👍

 

[Djapprentice]

a quick follow up question:

to see if I am understanding this correctly, there's only one doublet b/c the 2 "ortho" Hs are equivalent right?

thanks for explaining this in such detail! 👍

right

 

[artmed12]

exactly Euphoria, since they are equivalent and each see 1 H as a neighbor, you get 1 doublet. (1 neighbor H + 1)


P.S. I am taking topscore 2 tomorrow, and now my scores are skewed because i know the answer to an ochem question. I couldnt resist the challenge!

 

[houstongirl]

can someone explain to me why are we getting double and triple , it is not clear to me.

Thank you.