riobard (Hive Bee)
06-18-02 18:30
No 322887
      butyrolactone separation  Bookmark   

     SWIR was going to remove a vast amount of powdery solids from an oxidation of 484g THF in equimolar Ca Hypochlorite in 3L denatured ethanol. Here's a bit of background, then the question:
     C.500mL THF was added to a 4L glass vessel with 3L of denatured EtOH and 200 mL muriatic acid chilled in the freezer overnight. It was then placed in a large ice bath/cooler and set to stir mechanically. 25g 75% Ca(OCl)2  aliquots were added over a period of 8 hours with constant gooling and good ventilation to vent the Cl2 gas. The reaction vessel got quite hot to the touch during the period, and as powdery solids built up the magnetic stirrer stopped working, so a teflon stirbar retreiver was used to stir it at regular intervals of about 5 minutes for 1 minute lengths to throughly mix (fuckin took long enough too...). Chlorine fumes were slowly bubbled out over each addition until no more formed, or until patience got worn out and more hypochlorite was added.
     The vessel was removed from the bath after 2 more hours and allowed to reach room temperature, vessel heated on water bath to boiling and vacuum filtration began. But the shit plugged 7 qualitative grade filters to the point that the aspirator's vacuum boiled the mix at room temperature in the collected filter flask below. SWIR is running the stuff through a 2L funnel plugged with with a large cheesecloth to try and get some out before trying another vacuum filtration. Now here's the question:

    If SWIR were to evaporate off the alcohol and THF or at least reduce it to a total volume of below 1L(thus removing THF) after multiple filtrations, would he be able to make the suspension manageable by adding a nonpolar such as DCM? Or would all of the salts and fillers  still make a suspension that is impossible to cleanly decant from like the reaction mixture?

Steam distillation was carried out on a smaller run after the thf was positively removed by vacuum distillation. The thing about it that sucks is that the large amounts of water take forever and a day to evaporate off. DCM would be much easier and wouldn't require heat that can burn the lactone. Whadya think bees?
06-19-02 00:08
No 322993
      separation of gbl  Bookmark   

DCM should work nicely, but all that solid stuff from hypochlorite reaction isn't very convenient to deal with. There's probably all sorts of salts in there.. CaCl2 and maybe something else?

Boiling GBL won't "burn" it at all - I'm surprising as to where this information comes from as I've seen even molten NaGHB (with GBL residue) being heated to well over 200C to drive the GBL off and everything was fine without "burning" stuff.
(Hive Bee)
06-19-02 08:17
No 323076
      Distillation then..  Bookmark   

     I thought that the lactone would be ok to distill, but I wasn't sure. QW891 mentioned a polymerization when trying to distill the stuff. SWIR can't get it completelly clear by any rational means at my disposal, filtration just isn't working out.

     SWIR has stripped off almost all alcohol and all of the thf and the boiling solvent hasn't changed color too drastically, only tanned. Judging from the initial yellowish color of the suspended solids and the origional volume, it looks like a normal proportional thing to concentration. SWIM don't see any evidence of decomposition at all. Just thickening of color and viscosity.

(Hive Bee)
06-19-02 11:29
No 323117
      didn't work  Bookmark   

Well, the lactone was filtered until as clean as possible(still semi opaque) and alcohol reduced. it was about 300 mL of total impure liquid when it began foaming like boiling water and soap. It still was a simple tan color, although it became viscous and completely opaque.
    DCM was added to double the volume and stirred vigorously for c.15 min. MgSO4 was added to dry until it no longer settled, the mix filtered , and evaporation of the DCM commenced. Upon reducing the DCM, Only c.100mL was left in the flask when bubbling nearly ceased and then it immediately turned dark brown. SWIM thinks it's time to hang it up.

FUCK. I can't recall a bigger waste of one's time. It was a learning experience, but I still need to sort out just what wen't wrong.
(Hive Bee)
06-23-02 07:22
No 324369
      In the paper in which this reaction is based on ...  Bookmark   

In the paper in which this reaction is based on (Tetrahedron Letters, 23, 35-38) they also tried the reaction on ethanol, yielding ethyl acetate, so your choice of solvent might have been inappropriate. Your main product could well have been ethyl acetate.
(Hive Addict)
06-23-02 08:19
No 324375
      Ideas  Bookmark   

1. Don't use ethanol as the solvent. I could tell you right now that mixing ethanol and hypochlorite gives chloroform and sodium formate via the haloform reaction. That reaction doesn't happen immediately, only upon heating, and that's when the reaction goes uncontrollable! With adding hydrochloric acid into the mix, I'm sure you'd get that undesireable reaction to start at room temperature, and you'd get chloroform & formic acid. You could use a different solvent, like acetic acid or ...

2. What I'd recommend that you do, is go out and get some 10% NaOCl pool bleach and use that instead. In working, trying to make chloroform from acetone, I originally tried Ca(OCl)2. The solids formed in the reaction were a bitch. I went to 10% NaOCl, and it went wonderfully. Don't use the ethanol solvent either! It seemed to oxidize quite effectively in the presence of free chlorine. You should be able to oxidize THF to GBL in a solventless condition. Good luck on finding the right reaction parameters... I've got some ideas, but don't want to tout them as "the way to do it", because I've got no experience with the method.

3. In my experience, distilling GBL at atmospheric pressure will give you a distillate that is not colorless. I bet <<1% decomposes, so it's not a big deal in terms of losses.
(Hive Addict)
06-23-02 08:30
No 324377
      Damn!  Bookmark   

Read Post 3958 (Fuchem: "Oxidation of THF to GBL from Tetrahedron Letters", Chemistry Discourse). I guess the authors of the paper had the same ideas as me about using NaOCl. smile It seems however, that they shyed away from using it because it was harder to titrate. That's hilarious, I would have said the same thing about calcium hypochlorite over NaOCl. smile

Of course, there's also some good experimentation going on in Post 52700 (Cheapskate: "THF -> GHB part 2", Chemistry Discourse), but I noticed no one got around to using the 10% NaOCl and writing about it. It makes me wanna go buy some THF.
(Hive Bee)
06-24-02 07:30
No 324773
      Thanks guys  Bookmark   

Chromic and Moo, all i can give is my thanks at the moment. I didn't have access to the origional ref that the reaction was based on, only the procedure outlined by Cheapskate and QW891. SWIM will give another shot at things using an aqueous NaOCl and ethanol free setting, using equimolar hypochlorite to THF in some setting with manageable volumes. As it stands he has a 4L reaction vessel. If only we had better access to references on hypochlorite oxidations... Oh well.