11-12-03 10:21
No 470422
For a high boiling water insoluble organic oil (unsaturated ketone) what would be a good ratio of solvent to expected product. Haven't used DCM much so not really familiar. It seems almost like chloroform. Have been using about 3ml per ml. Did a couple little terts and it seems this may be way too much. Is there a rule of thumb to use?
(Synaptic Self-Mutilator)
11-12-03 11:41
No 470433
You don't really need much in this case. If it's a water insoluble ketone and you're extracting it from an aqueous phase, then you'll obviously be able to separate some of the ketone without a solvent, then just extract the aqueous 3x with a small amount of solvent.
You're talking about using like 1ml organic / 5mL aqueous... the best way to find these amounts is by trial and error. Keep track of your yields!
(Newbee)
11-13-03 21:21
No 470692
OK, Chromium thanks for the help. My CRC handbook does not show any azeos with DCM. It seems there should be some. Especially chloroform I would expect. Also this stuff absorbs acid like crazy. Aqeous phase is 50/50 v/v acetic acid. Should the acidity be neutralized before distilling off the DCM or is this just a waste of time? The product is the high boiling (250deg @760mm) ketone. I do want to reclaim the DCM. The last time I did this procedure I used PhMe and went straight to distill w/o neutralizing with no problems. But then PhMe forms a binary azeo with water. Anyway I know this is rather incomplete information to go on but any advice is appreciated.
By the way I extracted 5L liquor with 1.2L total DCM. 600/300/300ml increments. The third extraction had almost no detectable product using my rather crude analysis technique.
(Newbee)
11-22-03 00:51
No 472340
(Rated as: excellent)
After extensive searching, damn I wish there was a library around here, here are the common azeos of methylene chloride which are sure to be helpful to many.
30.0% acetone 57.6 degrees
11.5 ethanol 54.6
30.0 ether 40.8
8.0 ipa 56.6
7.3 methanol 37.8
51.0 pentane 35.5
1.5 water 38.1