Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: A2142 on March 05, 2007, 10:51:52 PM

Title: Triphenylmethanol unique protons- confused
Post by: A2142 on March 05, 2007, 10:51:52 PM

Hi all,

I was wondering if someone could help me with unique proton assignment for triphenylmethanol. I have attached an image with my initial thoughts.

Any help would be much appreciated.

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fi34.photobucket.com%2Falbums%2Fd142%2FAA225%2Ftriphenylmethanolprotons.jpg&hash=3dbb98dc3ad762868ef8063ea578d8001e63ab36)

Close-up of aromatic region on spectrum:

http://www.bama.ua.edu/~blacksto/CH237/spectra/exp4_triphenylmethanol_blowup_NMR.pdf

Title: Re: Triphenylmethanol unique protons- confused
Post by: ionic on March 05, 2007, 10:58:44 PM

i would suggest that there are only 4 unique protons in that spectrum. all six ortho protons =1, all six meta protons =2, all three para protons=3 and the alcohol proton =4

Title: Re: Triphenylmethanol unique protons- confused
Post by: alphahydroxy on March 12, 2007, 12:57:28 PM

Yep - I would agree...

I'm not sure quite why you feel that protons 6, 8 and 3 (for example) would be distinct in the NMR spectrum...?

Title: Re: Triphenylmethanol unique protons- confused
Post by: charco on March 13, 2007, 05:55:03 AM

I guess that the OP hasn't considered the tetrahedral nature of the central carbon and the free rotation about single bonds