Author Topic: Distilling THF from pipe cement  (Read 20143 times)

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Chromic

  • Guest
UTFSE. Heheh
« Reply #40 on: September 29, 2002, 09:49:00 PM »
Ahhh

Post 308130

(moo: "THF oxidations", Novel Discourse)
is exactly what I was looking for! Apparently 5 mol Br2 to 1 mol THF is the correct ratio.

"Purified tetrahydrofuran (1.0g, 0.014 mole) was treated with 12.0g (0.0705 mole) of Br2 in 15ml of water. The reaction mixture was stirred at 0° and the contents were monitored by pms spectroscopy. At the end of 2 days the bands of tetrahydrofuran had completely disappeared and only the bands of gamma-butyrolactone were present." (100% yield of GBL! Thanx moo!)

Getting closer! Now someone, tell me how to just use a catalytic amount of KBr and use H2O2 just to recycle the Br2...

H2O2 + 2 Br- + 2 H+ -> Br2 + 2 H2O

So that would mean if 5 mol H2O2 were slowly dripped onto a bit of KBr (say 0.5 mol) with 5 mol diluted H2SO4 (say 10%?) with 1 mol THF in the dark I could expect 5 mol GBL? The amount of reactants are worse than 2.1 eq of H2O2 for the Fe2+/H2O2 method, but... could be interesting if it actually works.

Any chance that would be explosive? Does that seem right? Comments please!  :)

Chromic

  • Guest
Calculations
« Reply #41 on: September 29, 2002, 10:01:00 PM »
If I'm right and using 20% H2SO4, that would mean something like slowly adding 48.6g 35% H2O2 (0.5mol) to 8.1ml THF (7.2g, 0.1mol), 49g H2SO4 (0.5mol), 196g H2O and 6.0g KBr (0.05mol). That seems entirely reasonable qtys... then extracting with DCM and distilling under reduced pressures... then life would be good.  :)

xboXer

  • Guest
on the cement mentioned
« Reply #42 on: September 30, 2002, 03:22:00 AM »
Refering to the plastic/pvc cement, and the extraction of THF, there is a primer product that is used pre-cement. It is called "OxxxY Purple Primer" I am almost positive this not only has a higher volume of THF, but may be an easier medium to extract from due to it only having solvents...,(acetone, cyclo, THF, MEK,)?

floating on a gyroscope, thumbing our nose at the universe, what a ride!

Chromic

  • Guest
Good idea, but...
« Reply #43 on: September 30, 2002, 07:43:00 AM »
Good idea, but the main time-limiting step in this reaction is not the extraction of THF... It's easy to get, say, 100ml of THF from pipe cement with only a couple hours of effort. However, converting the THF to GBL is the big stumbling block. I'd love to hear more comments.

Rhodium

  • Guest
Go for it chromic. I don't think it would pose ...
« Reply #44 on: September 30, 2002, 03:19:00 PM »
Go for it chromic. I don't think it would pose any explosion risk, but you better have good cooling handy if the reaction is very exothermic on larger scales...

Chromic

  • Guest
Does everything look right?
« Reply #45 on: October 01, 2002, 12:16:00 PM »
If the reaction mechanism only shows each THF molecule needing 1 Br2 molecule to form GBL, why are 5 needed?

Do the molar equiviliants look right? Thx, I plan to go ahead with this fairly soon.

Chromic

  • Guest
Nope!
« Reply #46 on: October 01, 2002, 06:40:00 PM »
From their MSDS:

PVC medium gray cement:
PVC Resin (Non-Hazardous) 12-17%, Methyl Ethyl Ketone 30-48%, Cyclohexanone 5-10%, Tetrahydrofuran 30-40%, Amorphous Silica 1-4%, Acetone <5%, Gray Colorant <1%

The heavy duty gray cement has 40-50% THF.

The purple primer cleaner has 1-5%! It's mostly acetone!
The purple primer has 10-15%! It's mostly methyl ethyl ketone!


The best is the PVC Heavy duty gray fast set cement with 65-75% THF, but since it's not found around here I'll stick with the medium gray stuff.

Chromic

  • Guest
Preliminary results
« Reply #47 on: October 02, 2002, 01:54:00 PM »
I tried mixing 3.6g THF (50mmol), 14.7g H2SO4 (150mmol), 58.8g H2O & 3.6g KBr (30mmol) then dripped in 14.6g 35% H2O2 (150mmol). The flask went a deep orange as the hydrogen peroxide formed bromine from the salt, and the vapors have filled the flask (but are contained). There hasn't been any real significant temp increase.

Is this flask going to turn clear & colorless when it's done? How will I know when the rxn is done? Do I just quench with bisulfite (is this necessary?) and extract with say 5x15ml DCM?

This route seems like too much work.  :(  I wish someone could shed some light on using dichromate or permanganate... but I bet I'm the only one interested in making gbl this way.

weedar

  • Guest
I'm very interested..
« Reply #48 on: October 02, 2002, 02:10:00 PM »
You must also remember that not all of us are able to
experiment like you do. Please, keep up the good work! :)

Weedar

Save the Temporary Couch! And whales.

Chromic

  • Guest
Hmm
« Reply #49 on: October 02, 2002, 04:10:00 PM »
Well, it looks like there's little oily droplets at the bottom of the flask. That sure doesn't look like GBL. I'll work it up and hope for the best.

Can anyone get me p169 (ACS monograph 186) of Milo Hudlicky's "Oxidations in Organic Chemistry" (call # QD281.O9 H83 1990)? It talks about Cr(VI) oxidations of cyclic ethers.

Perhaps some permanganate / copper sulfate without the alumina solid support is worth trying...

Chromic

  • Guest
What the FUCK did I make?
« Reply #50 on: October 02, 2002, 05:51:00 PM »
I added sodium bisulfite until the orange went away and transferred it to a sep funnel... at that point I noticed my eyes were burning and starting to tear...

My EYES!!! ARRRGH. I think I made some sort of tear gas.

Down the drain that goes...

weedar

  • Guest
Chromic
« Reply #51 on: October 03, 2002, 04:15:00 AM »
you are wearing goggles, right?

Safety first.

Weedar

Save the Temporary Couch! And whales.

Chromic

  • Guest
bromoacetone
« Reply #52 on: October 03, 2002, 08:49:00 AM »
I'd place my money on it being bromoacetone. There is some small percent of acetone in the pipe cement, and I bet that was responsible for my uncontrolled tearing... never again...

xboXer

  • Guest
And for this one
« Reply #53 on: October 06, 2002, 10:30:00 PM »
Stop here and make a fume cabinet. It is real easy and will prolly preserve you a day or two longer...

Take two auto A.C. blowers that are encased in a houseing, seal all the seams with epoxy. Get an old bead blasting cabinet that is stripped, and mount new safety glass (w/a lexan layer to the outside) to the top of the cab, cut holes for the vac opening of the blowers, mount w RTV (fat bead) fashion ducting, (heavy dryer exaust duct works good, you can give each thier own exaust, but put a balance tube between) The exaust fans being D.C. gives an optional battery back-up ability if you want to keep cooking during the hurricane. Judiciously make some intakes, but calculate the area of the holes, to the fans vacuum potential, so that you develop a slight neg. pressure inside the cabinet. If you have some real goliath exhaust fans, you wouldn't need to mount gloves on the cab. (but then you would have that 'whys them lil cuts on my hands STINGING?') The other option is to provide a pos. pressure from under, exhaust through the top. This works good if you have 'heavy' gasses developing anywhere along the way...
Bromide gases/compounds heavy? yes-no???
anyway, save the sacs, AIR SACS that is...

floating on a gyroscope, thumbing our nose at the universe, what a ride!

spectralmagic

  • Guest
It *is* possible...
« Reply #54 on: February 06, 2003, 01:17:00 PM »
Chromic said:

I'm completely convinced now, that [GBL] can't be made by aqueous oxidation using hypochlorite.



SWISM would like to report 32% yield after distillation, using aqueous Ca(OCl)2 & HCl, oxidizing THF to GBL, starting with 50g of THF (mostly-pure, distilled from pipe cement).  He'd also like to report that this is one nasty reaction from an odour perspective, best to plan in advance where all the chlorine gas is going to go...

The crude GBL after recovering the extraction solvent (DCM) but before distillation was yellow, murky, and smelled somewhat chlorinated, lots of forerun during distillation, presumably chloro-hydrocarbons of some kind (or MEK, or both?)...

SWISM has just noticed a post on this reaction being done in DCM instead of H2O (but no acid?)...  will most likely try that next!