December 11, 2019, 12:02:44 PM
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Topic: Strange Reaction Product  (Read 330 times)

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Offline JSUCY232

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Strange Reaction Product
« on: October 04, 2019, 06:23:44 PM »
I am attempting to make a biopolymer by functionalizing PVC with a sulfhydryl group, then forming a disulfide bond to a protein.  I am using PVC because I already had finely powdered PVC lying around. This is from a commercial source, so purity is unknown. Yesterday I did this reaction: I reacted 5 grams of PVC in 50mL of MTBE (which I knew would not dissolve the PVC, but I was trying to do a solid phase reaction) and about 2 grams of NaSH. This was done in a fume hood. Heated to 65C with stirring. Nothing was happening, so I added about 25 mL of dry methanol. The mixture quickly (over about 5 mins) turned green. I did not notice gas evolving, but I was stirring. I assumed the green color was due to the dissolution of the yellow NaSH, but now I think it could have been Cl2. Over about the next 15 minutes, the mixture became white again. I continued to heat under a reflux column for about 6 hours total. The product was vacuum filtered and washed with methanol under vacuum. I hoped to find an SH peak in IR but did not observe that. Instead, I observed a HUGE OH peak. I sat the white powder to dry overnight and ran IR this morning. I observed the same huge OH peak and also noticed an additional peak around 1700 where one would expect to find a carbonyl. I have attached the IR. Pure PVC is in red, and my product is in blue. I found this puzzling, so I would appreciate any input.

Offline JSUCY232

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Re: Strange Reaction Product
« Reply #1 on: October 04, 2019, 06:26:06 PM »
I don't see how I could have produced an acid, but this reaction was performed in a regular fume-hood, not under inert conditions. I will try to run NMR when I get a chance, but I have not purified this product at all, nor have I tried to dissolve it.

Offline wildfyr

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Re: Strange Reaction Product
« Reply #2 on: October 07, 2019, 01:13:32 PM »
Reactions with polymers already are often low efficiency, doing it solid phase is even worse.

I would be pretty surprised if that reaction worked honestly. I did a bunch of research this year on making thiols, and seldom saw direct NaSH.

Perhaps try this: use sodium thioacetate, then hydrolyze with acid. Good way to make a thiol from alkyl halide.

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