TheBlindGenius (Hive Bee)
10-29-02 18:42
No 374331
      Ketone purification via NaI  Bookmark   

I was visiting Rhodium's site a few days ago and perusing the links to see what I understand better now that I have some college chemistry experience under my belt and I ran into Hellman's ketone purification technique using sodium iodide.  I have some questions about the method.  First, is it any better than the bisulfite method (i.e. does it purify ketone to a larger extent)?  Second, I don't understand how it doesn't polymerize the ketone, since you have to bring it to reflux, maybe even twice!  Don't you have to reach the boiling point of a substance to reflux?
 
 
 
 
    Osmium
(Stoni's sexual toy)
10-30-02 04:47
No 374488
      Since the desired reaction seems to take place at ...  Bookmark   

Since the desired reaction seems to take place at a sufficient rate when lower ketones are refluxed, it shouldn't be necessary to heat MDP2P etc. all the way to their reflux temperatures. I assume 50-100C should be sufficient in that case.

I'm not fat just horizontally disproportionate.
 
 
 
 
    madprosr
(Newbee)
11-01-02 11:12
No 375434
      swim is curious about this method too, there ...  Bookmark   

swim is curious about this method too, there seems to be a shortage of trials with actual yields posted... like for impure ketone (peracid/oxone/wacker) and foronce-distilled ketone. props to hellman for reading Vogel's, but hellski can go suck a fat dick. and hellman's yields (20g from 60g red ketone) are quite unappealing.

swim added 1.5ml ~= 1.2g acetone (58g/mol) to 1g NaI (150g/mol) (should be a slight excess of acetone if it really bonds 3:1) at room temp, then put in on an ice bath. completely crystallizes in 1h. yielded 1.3g, not quite right.
slowly decomposes at room temp releasing iodine (turns paper black).
swim supposes it should come out right with enough acetone to balance that lost by evaporation as Osmium posted a ref confirming MEK + NaI in 3:1 ratio.

swim really wants DATA, as vac distilling ketone at 180C tends to burn half of it... oh, and if you do try it, do like hellman says and add the NaI before heating, adding it to 200C ketone is a good way to liberate iodine gas.