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Author: Subject: Leftovers from bromoethane synthesis
Newton2.0
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[*] posted on 18-9-2021 at 16:06
Leftovers from bromoethane synthesis


I was synthesizing EtBr using a common method and found that there was a considerable amount of residual clear, crystalline solid in my boiling flask after the reaction completed.

Now, I assume that the majority of the solid will be a mixture of sodium ethyl sulfate and unreacted sodium bromide. The reaction was, unfortunately, very low yielding and I am wondering if some conditions favored the formation of sodium ethyl sulfate and did not allow for the sodium bromide to react.

Can anyone else comment on the byproducts of this reaction?
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[*] posted on 18-9-2021 at 19:17


What order did you mix the reactants in?



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[*] posted on 18-9-2021 at 20:26


Please supply more details of your reaction. I.e., reference, balanced reaction scheme, writeup including temps, reagent amounts, procedure, etc.



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Amos
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[*] posted on 19-9-2021 at 10:16


In any of the reaction conditions I'm familiar with, sodium ethyl sulfate and ethyl bromide are both products of an equilibrium with the reactants and should thus be able to inverconvert. Because ethyl bromide is the more volatile product, it should be able to be distilled out, reacting away sodium ethyl sulfate; there shouldn't be any "dead end" caused by the formation of it as you've hypothesized. While I havent actually seen your procedure yet, I think it's more likely that the reactants weren't given enough time to react, distillation was stopped too early, or too much water/not enough sulfuric acid were present.
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[*] posted on 19-9-2021 at 14:09


Not enough water is also a significant problem with this synthesis. 80 proof vodka works well as a source of ethanol. Yield should be 80-90% easily unless you didn't have enough cooling to condense the product.
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