Can anyone please tell me what is the best way to remove a trace quantity of sodium iodide (NaI) from a solution of Ethyl acetate-hexanes mixture? It's from a Finkelstein reaction. Even after Na2S2O3 washing multiple times, the organic layer keep turning brown/pink. It should be due to the tiny amount of remaining NaI in the organic layer. Is there an efficient method that will completely remove the NaI?
Thanks a lot in advance.
Personally, I have never performed the Finkelstein reaction, so I am not too sure, what is commonly done to remove excess NaI. I have a few questions though: 1) Given NaI s solubility in water, will several water washes not help to remove it? 2) If I remember correctly, it is persulfate ion (S2O82-) which oxidizes iodide to iodine (S2O32- does the reverse; converts iodine to iodide). Would S2O82- washes help?
Hi
Sodium iodide is used for conversion of an alkyl chlorides into an alkyl iodides. This method, the Finkelstein reaction, relies on the insolubility of sodium chloride in acetone to drive the reaction:
R-Cl + NaI → R-I + NaCl
Stable under normal temperatures and pressures. May discolor on exposure to
light. Air sensitive. Light sensitive. Hygroscopic: absorbs moisture or water
from the air.
The brown/pink colouration that appear might be due to the formation of iodine. The removal of iodine is making by using 5% HYPO - SODIUM THIOSULFATE.
Find in attach, a note about preparing and using of 5% HYPO - SODIUM THIOSULFATE.
As well as, find below a link on a patent about this removal.
https://www.google.com.eg/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&uact=8&ved=0ahUKEwi_yfGi58fMAhWMDRoKHckXCTIQFggtMAM&url=http%3A%2F%2Fwww.google.com%2Fpatents%2FUS3050369&usg=AFQjCNFYPxTyfEJiXq6B3gf7fa7ci2nIsA&bvm=bv.121421273,d.d2s
Try to add some water and HgO/AcOH, ration 1:2. HgI2 formes big orange precipitate. No reason to wash EtOAc with Na2S2O3, because it bears reuctive functions only.
The removal of iodine is making by using 5% HYPO - SODIUM THIOSULFATE.
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