Should we consider H on OH in NMR for the DAT?

[StudentDoc1234]

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Some websites and books have the hydrogen from OH showing on the NMR spectrum yet some don't. I know the OH is a wild card for the HNMR but I want to be sure if we should expect it to show on the spectrum for the DAT. Another question, should we consider a benzene ring to have only 1 signal showing for their hydrogens even if it has asymmetrical constituents on the ring?

 

[DAT Destroyer]

Some websites and books have the hydrogen from OH showing on the NMR spectrum yet some don't. I know the OH is a wild card for the HNMR but I want to be sure if we should expect it to show on the spectrum for the DAT. Another question, should we consider a benzene ring to have only 1 signal showing for their hydrogens even if it has asymmetrical constituents on the ring?

Wild Card ? Indeed not....the Hydrogen form an OH may appear in various positions due to the extent of hydrogen bonding, but is an important signal. The signal may be upfield, midfield, or downfield. If the H is from the OH group of a carboxy acid....it is a very valuable piece of info !!!!!! You would see a signal around 11-13 ppm.

Now for your other question....

The benzene signal may be single.....or even split if electron withdrawing groups are directly attached as in an ether linkage..... or even nearby as in a carbonyl linkage. Go to an Organic text and have a look for yourself.....molecules that have ethyl groups will not likely show a split ....thus we see a single signal around 7 ppm....

If you have a methoxy group......you will see split signals. A nice little trick I show my students is to look for a DOUBLET of DOUBLETS around 7-8 ppm.....this often signifies a 1, 4 disubstituted benzene ring.

I hope this helps......

Thank you for such a delightful question.

Dr. Jim Romano

 

[StudentDoc1234]

Got it- thank you for the detailed response!

 

[DAT Destroyer]

Got it- thank you for the detailed response!

Keep up the good work champ!

 

[BYU4you]

Definitely know OH