How to determine %conversion of monomer (sodium 4-styrenesulfonate) to polymer (sodium poly-(4-styrenesulfonate)) using 1H-NMR? Kindly provide step by step process. Thank you.
You should start by recording 1D of sodium 4-styrensulfonate, it should look like the predicted spectra attached. CH2-CH- has a signal that will change upon polymerisation, so you should follow how those peaks disappear during the course of your reaction. You can set a time course experiment in Topspin.
Domenico Sanfelice. Thank you for your effort to help me and the spectrum. I have, say about 8 spectra, collected during the progress of the polymerization process collected at a regular interval. I now want to know the procedure to calculate the % conversion from monomer to polymer. Can you help me step by step process? What do you mean by "1D" and "set time course experiment in Topspin"? Would you please explain. Thank you once again.
Why don't you upload the first and last experiment that you have acquired, I can highlight you what I mean?
Regarding the 1D experiment, I refer to this:
http://www.cryst.bbk.ac.uk/PPS2/projects/schirra/html/1dnmr.htm
And the time course experiment is what you have done, just you can tell the software to record 1D experiment at regular time interval without being there pushing the buttons!
Depending on your degree of polymerization, you should not use end-group analysis once you are reaching 95% conversion or more than 20mers. NMR is not accurate beyond a 19:1 ratio. Shout-out to the must-read paper: https://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-0030-1259018
Then you can start using 13C satellites! Ratio of the major component to the solvent peak, and ratio of the minor component to the C13 satellites, and then correct for the natural abundance of C13 (1.1 %) and you are in business. That allows you to increase sensitivity by two additional orders of magnitude.
Dear colleagues, can any one give more explanation about using 1H NMR in quantitative analysis of small molecules in mixture...
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