Chromic (Hive Addict)
04-09-01 11:02
No 183149
      bisulfite addition product (test run)  Bookmark   

I was reading about the bisulfite addition purification process. It seems as though it's a great qualitative test for ketones, but how well does it work well for phenylacetones?

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I tried following Eleusis' prep but using a 4x molar excess on a small batch (using potassium metabisulfite), just using acetone. I get some cloudiness, is that my precipitate? There's way less than a gram when filtered after an hour (and I used 0.8g of acetone) I wanted to do a test run, is there any other ketones (other than my favorite one) that I can use and are easily available?

What does the precipitate look like with MDP2P or PMP2P?
 
 
 
 
    terbium
(Hive Addict)
04-09-01 17:54
No 183167
      Re: bisulfite addition product (test run)  Bookmark   

I have prepared the sodium bisulfite addition product with MDP2P and it works well, giving a white precipitate. I wonder what the solubility of the potassium bisulfite is in water and alcohol? If the solubility of the potassium bisulfite is much less than the sodium bisulfite then perhaps this could be a problem.

The procedure I have used follows Vogel as in the following example that prepares the sodium bisulfite addition compound of cyclohexanone.

Prepare a saturated (aqueous) solution of sodium bisulfite from 40 g. of finely powdered sodium bisulfite: about 70 ml of water are required. Measure the volume of the resulting solution and treat it with 70% of its volume of methanol; add sufficient water (about 45 ml) to just dissolve the precipitate that separates. Introduce 20 g. of commercial cyclohexanone into the aqueous-alcoholic bisulfite solution with stirring and allow the mixture to stand for 30 minutes; stir or shake occasionally. Filter off the precipitated bisulfite compound at the pump, and wash it with a little methanol.
 
 
 
 
    blue
(Delicioso!)
04-10-01 08:21
No 183309
      Re: bisulfite addition product (test run)  Bookmark   

chromic - ditto, sodium metabisulfite work awesome on mdp-2-p and acetone forming crystals within moments, sounds like the potassium salt ain't cutting it.

btw-sodium metabisulfite is easily available otc at wine making stores as a bottle dissinfectant 1kg = $10, so why piss around with potassium?


is it soup yet?
 
 
 
 
    Chromic
(Hive Addict)
04-10-01 10:08
No 183326
      Re: bisulfite addition product (test run)  Bookmark   

Thanx guys, not seeing sodium metabisulfite at the wine store, I picked up the potassium metabisulfite thinking the cation didn't make a difference. It seems like it makes all the diference in the world.
 
 
 
 
    Osmium
(Stoni's sexual toy)
04-10-01 10:32
No 183328
      Re: bisulfite addition product (test run)  Bookmark   

The whole business works well without the alcohol too. I used to wash the precipitate with denatured, followed by ether for a quick dry sample.
 
 
 
 
    foxy2
(Distinctive Doe)
12-09-01 00:10
No 245797
      Re: bisulfite addition product (test run)  Bookmark   

I was thinking the Hive needed a little review of this procedure. What works, what dosn't ect. 

This thread is a good primer.  It appears that Sodium Bisulfite and Metabisulfite are prefered, possibly due to higher solubilities.  However the Potassium salts also seem acceptable.smile

Here is the procedure from Rhodium for useing Sodium Bisulfite.
../rhodium/chemistry /eleusis/bisulfite.html

Good discussion, labgrrrl likes bisulfite
Post 99572 (boingo: "bisulfite questions", Chemistry Discourse)

Fiendly Finger claims that Metabisulfite works, I assume its Sodium?
Post 201753 (FriendlyFinger: "Re: Distilling mdma oil", Newbee Forum)

Thread with practical info
Post 24638 (Antibody2: "Bisulfite purification questions", Chemistry Discourse)

The following thread also holds some good info
Post 18907 (Rhodium: "Re: OTC sodium bisulfite??", Chemicals & Equipment)
In which Rhodium said
Merck Index:
Sodium bisulfite, NaHSO3.
The commercial product consists almost solely of sodium metabisulfite (Na2S2O5) and for all practical purposes possesses the same properties as the true bisulfite.

Here are some misc bisulfite posts
Post 186922 (Chromic: "Re: Potassium Monoperoxysulfate for spas~", Chemistry Discourse)
Post 124526 (Bankrobber: "Maybe This Works If So Whoooeee!", Newbee Forum)
Post 105853 (scwam: "Adding additional bisulfite in solution", Chemistry Discourse)
Post 102212 (Semtex Enigma: "Bisufite, let us get some closure on this...", Chemistry Discourse)
Post 172106 (DUMFuk: "Bisulfite", Chemistry Discourse)

This ones for you locriansmile

Do Your Part To Win The War
 
 
 
 
    locrian
(Hive Bee)
12-09-01 14:22
No 245933
      Re: bisulfite addition product (test run)  Bookmark   

Ahhhh . . . foxy, you shouldn't have . . . 'preciate it though.  laugh
 
 
 
 
    Chromic
(Hive Addict)
12-09-01 15:29
No 245951
      Re: bisulfite addition product (test run)  Bookmark   

Follow the procedure Terbium gives using sodium metabisulfite or sodium bisulfite:
Prepare a saturated (aqueous) solution of sodium bisulfite from 40 g. of finely powdered sodium bisulfite: about 70 ml of water are required. Measure the volume of the resulting solution and treat it with 70% of its volume of methanol; add sufficient water (about 45 ml) to just dissolve the precipitate that separates.

Store it in an airtight bottle until you use it with as little air space as possible, or it will absorb oxygen from the air and become useless. Potassium bisulite and metabisulfite do work, but they seem to react slower.
 
 
 
 
    Goodtimes
(Hive Addict)
12-10-01 15:21
No 246232
      Re: bisulfite addition product (test run)  Bookmark   

Great links foxy, THX!! laugh

"The gods are too fond of a joke."  (Aristotle)