I synthesized a methacrylated product from a hydroxy fatty acid. It's a very complex mixture of at least 3 - 4 compounds, which may have varying degrees of unsaturation as a result of the added methacrylate groups.
For some reason, my Wijs method Iodine Value Tests are not working right. My test on the starting hydroxy fatty acid (possible mixture of isomers) yielded 88, which conforms to literature and commercial values, but my product yielded around 80. These were repeated at least 2 times and the results were consistent. NMR results show that there are extra double protons corresponding to methacrylates and my product was able to photocure well. My seniors think it may have to do with the iodine not attaching properly to methacrylate groups. I can't quite put my finger on this. Please help.
Yes, indeed. Your suggestion was exactly something we agreed on, but we just wanted a more direct method to cross-reference, especially since my NMR spectrum does not look pretty. Thank you for the attachment Michael!
Have you considered IR? Iirc, conjugated ester should be fairly easily distinguished from the others. Also you should see the OH vanish if you can get it dry enough. Not sure about quantification, but if it works it's easy and fast.
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