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Topic: Such in trouble with NMR Spectra PCBL in m-cresol d8  (Read 6119 times)

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Offline nitro

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Such in trouble with NMR Spectra PCBL in m-cresol d8
« on: August 31, 2007, 12:45:17 PM »
Hi,


In my research I try to see a inverse transition helix-coil of Poly-(epsilon)CarboxyBenzyloxy-L-Lysine (see the monomer). I have 14 spectra at different T°.

First I have a peak at 8ppm (15°C) integral 6 (Aromatic integral =5)??? and at 50°C this peak is shifted at 7.35ppm integral 3.5
And I'm pretty sure is not the aromatic, because I have a stable peak at 7.24ppm.

Next is the peak at 0.8ppm kind of unusual chemical shift.

So all help and clue are welcoming. thanks.
Have a good day.

Offline muse

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Re: Such in trouble with NMR Spectra PCBL in m-cresol d8
« Reply #1 on: October 28, 2007, 01:11:35 PM »
Hi

Where is your amine and hydroxyl groups? They typically have different shift values when you change temperature. From your spectra it seems that the integral between the aromatic hydrogens at ~7.24 and your signals at 8ppm and 7.35pmm are constant.

NMR shifts around 0.8pmm may come from highly shielded protons, like (CH3)3CH. Lock in a chemical shift table. http://www.chem.wisc.edu/areas/reich/Handouts/nmr-h/hdata.htm

-M

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