NMR question please explain

[navneetdh]

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I chose the answer is 1 singlet and 1 doublet

but the answer is 2 singlets.

Please explain someone.🙁

 

[sixkiller]

I chose the answer is 1 singlet and 1 doublet

but the answer is 2 singlets.

Please explain someone.🙁

Methyl hydrogens ~1.0 singlet

Aryl hydrogen ~7.0 singlet

Examine the structure for symmetry...remember that spin spin splitting is only due to NON-EQUIVALENT neighboring hydrogens...

 

[navneetdh]

Methyl hydrogens ~1.0 singlet

Aryl hydrogen ~7.0 singlet

Examine the structure for symmetry...remember that spin spin splitting is only due to NON-EQUIVALENT neighboring hydrogens...

why are aryl hydrogens a singlet? I though the rule was n+1

so each hydrogen has 1 hydrogen on neighboring carbon---that makes 1+1=doublet-- no??

 

[sixkiller]

why are aryl hydrogens a singlet? I though the rule was n+1

so each hydrogen has 1 hydrogen on neighboring carbon---that makes 1+1=doublet-- no??

No...again, you are applying spin spin splitting (n+1 rule) to equivalent hydrogens. The n+1 rule only applied to chemically non-equivalent hydrogens. Thus, your reasoning is flawed.

Examine the structure, specifically the aryl hydrogens....

Are they chemically equivalent? Yes, therefore no splitting.

 

[navneetdh]

No...again, you are applying spin spin splitting (n+1 rule) to equivalent hydrogens. The n+1 rule only applied to chemically non-equivalent hydrogens. Thus, your reasoning is flawed.

Examine the structure, specifically the aryl hydrogens....

Are they chemically equivalent? Yes, therefore no splitting.

Oh I think I sorta get it----if the 2 hydrogens on the neighboring carbons are chemically equivalent they will only give singlets Right?? no matter what they are.

Will this be true for H3CCH3?? will I see 1 singlet or will i see 1 quartet?

 

[sixkiller]

Oh I think I sorta get it----if the 2 hydrogens on the neighboring carbons are chemically equivalent they will only give singlets Right?? no matter what they are.

Will this be true for H3CCH3?? will I see 1 singlet or will i see 1 quartet?

Bingo!

You should actually look up NMR charts to get a better feel for this stuff.

Here is a website where you can look up almost any compound including the IR and Mass Spec.
http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi

Yes, ethane would give one singlet at ~1.0.

 

[navneetdh]

Bingo!

You should actually look up NMR charts to get a better feel for this stuff.

Here is a website where you can look up almost any compound including the IR and Mass Spec.
http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi

Yes, ethane would give one singlet at ~1.0.

Thank You soooo much. I will definitely look at the site but I really appreciate your help. 👍👍👍🙂 feels like a light bulb turned on in my brain h aha h a