Author Topic: Distilling THF from pipe cement  (Read 20150 times)

0 Members and 1 Guest are viewing this topic.

Chromic

  • Guest
Distilling THF from pipe cement
« on: June 25, 2002, 05:40:00 AM »
I've gone through the search engine, and haven't found any information on how to distill pipe cement to get the THF and the other solvents out. As Ab2 said in another thread, that if one was to use their glassware to distill this stuff, one would need all the recovered THF just to clean the flask...

I'm thinking about distilling it straight from the can using a water bath.

Has any one got experience doing this? What did you use? Did you do anything to prevent peroxide formation?

This is a 16 fluid oz can of a popular brand of gray PVC cement mentioned elsewhere on the Hive in other threads.

I'm thinking that it might be worthwhile to obtain another source of THF. This looks a lot worse than distilling the DCM-containing goop that's sold as paint stripper.

Elementary

  • Guest
Solvents
« Reply #1 on: June 25, 2002, 06:08:00 AM »
After looking at some MDMS data for various PVC cements these seem to be the solvents used :

Methyl Ethyl Ketone (40-55%) (BP = 79.6°C)
Tetrahydrofuran (25-40%)  (BP = 66°C) SEE NOTE
Cyclohexanone (5-10%)  (BP = 155.6°C)
Acetone (0-5%)  (BP = 56.5°C)
(PVC Resin (10-14%))

NOTE : Must be distilled with a reducing agent, as explosive peroxides may form (see Merck Index).

You may have a hard time seperating acetone, MEK and THF !



John Lennon - Working Class Hero

metwurst

  • Guest
H2O to start with
« Reply #2 on: June 25, 2002, 06:42:00 AM »
Perhaps a water wash is in order first. THF is soluble to 300g/L in water. The MEK and acetone are also soluble, but are both ketones, so saturating the resulting water/THF/MEK/acetone with bisulfite might crystallise them out leaving  THF in water.
Sound plausible?

Elementary

  • Guest
:-
« Reply #3 on: June 25, 2002, 07:19:00 AM »
The PVC resin may stop a lot of the solvents from going into the water.

You may still have to distill first, to get the solvents away from the resin.

But your bisuphite addition idear seems plausable, as long as the THF does not react with the bisulphite.

John Lennon - Working Class Hero

Ritter

  • Guest
WARNING!!!
« Reply #4 on: June 25, 2002, 08:50:00 AM »
Chromic:

I don't have the time to go through old posts to ref a post#, but I specifically remember one of the guys from back in the day (maybe Cheapskate?) distilling THF from PVC cement with near disasterous results.  The low grade ethers in those cement products are LOADED with peroxides.  There was at least one report here in the past which detailed a powerful explosion resulting from the distillation of THF from pipe cement.  BE CAREFUL!!  If you are going to do this, be sure to use a blast shield and have a good CO2 fire extinguisher at the ready in case the worst happens. 

Better yet, PM me and I'll hook you up with a company which sells THF cheap, no questions asked.

moo

  • Guest
According to my memory (which is not perfect) ...
« Reply #5 on: June 25, 2002, 01:03:00 PM »
According to my memory (which is not perfect) cheapskate had an accident while reluxing the stuff, not distilling it. It is  a little hard to believe that the THF used in glues would be unstabilised, after all it is intended to be used by non-chemists and has no warning labels about peroxide risk whatsoever (that would be obligatory wouldn't it?). The distillation has been performed straight from the can with a still fabricated from copper pipe, although only approximately half of the THF was distilled. Yes, there might be peroxides lurking in the can, but one could try to apply ferrous salts to the stuff to decompose them. I can't say I'm certain about this, so don't blame me if you get killed :P .

sYnThOmAtIc

  • Guest
peroxides
« Reply #6 on: June 25, 2002, 08:47:00 PM »
Well the glue is not sold to be distilled or refluxed for one. And as far as I know the peroxides are only dangerous when heated so plumbers ans plastic workers are in no danger as long as the product is being used as for what it is made for. Plus the cans do say that they contain flammable toxic solvents and to use only as directed in good ventilation. I highly doubt you could ever hold the company liable after an explosive reaction during a distillation of a product that has no place in your flask.

Chromic

  • Guest
Removing peroxides
« Reply #7 on: June 25, 2002, 11:53:00 PM »
What chemicals, besides FeSO4, can be used to remove the peroxides?

I may just look for another product for the THF, but I'm very interested in getting it OTC.

sYnThOmAtIc

  • Guest
Please
« Reply #8 on: June 26, 2002, 01:15:00 AM »
Chromic, Can you please post any info you have about removing peroxides from THF. If you have any info about nitroethane I'd appreciate it cause smiw believes he should distill it before its long life in the freezer.

starlight

  • Guest
peroxides
« Reply #9 on: June 26, 2002, 10:03:00 AM »
Vogel says you can remove peroxides from THF by:

a) passing through an alumina column
b) shaking with Iron II sulphate.

I'm afraid I'm not sure as to the practicality of these methods with regard to pipe cement as I have never seen it and am not sure of its consistency / viscosity / makeup

Osmium

  • Guest
Just add some motor oil and don't bother about ...
« Reply #10 on: June 26, 2002, 10:55:00 AM »
Just add some motor oil and don't bother about the peroxides. They aren't volatile and will stay behind, being safely diluted with the oil and other high-boiling stuff left in there.

I'm not fat just horizontally disproportionate.

Chromic

  • Guest
Excellent
« Reply #11 on: June 26, 2002, 10:58:00 AM »
Thanx for the ideas. I'll perform the distillation on a water bath as well to minimize my troubles... rigging a still head to the can is going to take some thought...

former_chemist

  • Guest
Use toluene or xylene
« Reply #12 on: June 26, 2002, 11:51:00 AM »
If the mix is too thick use toluene or xylene to thin it.  Both of these will be readily oxidized by any peroxides formed.  Xylene has the higher boiling point so separation should be cleaner.

Hansje

  • Guest
water and salt
« Reply #13 on: June 26, 2002, 01:57:00 PM »
I don't know what the pipe cement they sell around your place is like, but the stuff they sell here can be extracted like this:

1. Add about three quarters of the volume of water to the cement and stir. Be amazed to see that the PVC and all other non water miscible ingredients clot together in a big ball, that, believe it or not, isn't even sticky.

2. Filter everything through a piece of cloth. Wring out to catch as much liquid as possible.

3. Add 400g of table salt per liter of added water and stir. Presto: all organics float to the top.

4. Separate.

5. Distill top layer to get THF, MEK and whatever else is in there that you want.

Hansje high in proteine and fibre!

Cheapskate

  • Guest
Let me verify that
« Reply #14 on: June 26, 2002, 05:13:00 PM »
The procedure above that details adding water to remove the goop from pipe cement works quite well with the materials I have available also.  I never thought of using salt to separate it though, I just distilled the entire mess.

Water did a pretty good job of getting rid of the goop though.

Chromic

  • Guest
Hansje
« Reply #15 on: June 26, 2002, 11:50:00 PM »
Hansje, if this works with the O___y brand of gray cement... I will love you.

Thank you!!!

isop

  • Guest
HOW do you know it really works??
« Reply #16 on: June 27, 2002, 07:01:00 AM »
Hansje,
Have you actually CHECKED that your THF obtained by adding water to kick PVC out of the solution and then salting out the THF really works?

What I am concerned about is that the plastic you see coming out after adding water are only the longest polymers and the short PVC fibers still stay in the solution.

The obvious way to test this would be to vapourise on a glass plate some of the THF obtained in this manner to see if any residue is left.

Hansje

  • Guest
THF
« Reply #17 on: June 27, 2002, 09:39:00 AM »
Chromic: If you have any choice, go for the glue that is used to cement narrow-fitting hard-PVC pipes together. It will be highest in THF and lowest in polymers. Over here that is a clear, tannish, very viscous liquid. The gray stuff (again: over here) is used for wide fittings and has a lot more fillers in it.

isop: Sure, the liquid obtained by the separation is by no means pure THF. But the idea is that you distill it. Collect very little below 66°, a large fraction between 66° and 75°, have some polymeric crap fall out of solution at this point (so yes: you were right about that). Left in the flask is said crap and water, that only faintly smells of solvent. I know this is not scientific proof, but what would your guess be?

Hansje high in proteine and fibre!

isop

  • Guest
OK
« Reply #18 on: June 27, 2002, 11:20:00 AM »
Right, if you perform a distillation at the end of whatever you do, it should be OK. Didn't read your post very carefully  ::)

Chromic

  • Guest
Distilling THF
« Reply #19 on: June 27, 2002, 03:08:00 PM »
Thanks Hansje! Is storing the organic phase over aqueous sodium bisulfite good enough to inhibit peroxides?

Hansje

  • Guest
safe
« Reply #20 on: June 28, 2002, 01:48:00 AM »
I have always assumed that distilling the mixture without adding reductant is quite safe due to the considerable amount of water in there. Fate hasn't proved me wrong yet  :) , but don't take my word for it, I'm just guessing.
You'll need to add some peroxide scavenger if you want to store your THF after distillation. Not bisulfite solution if you don't want to distill again.

Hansje high in proteine and fibre!

Chromic

  • Guest
Bisulfite good enough
« Reply #21 on: June 28, 2002, 07:59:00 AM »
It seems that a sat sol'n of bisulfite forms a separate layer, and so, that's fine if I'm just using the impure THF for oxidizing with NaOCl. I might stall a bit on this procedure... I'm not as excited to oxidize THF as I once was... especially when all the dangers are taken into account... I've done some crazy stuff (like making Et2O)... but the thought of an ether and an oxidizing agent initimately together is really starting to scare me.  >:(

Antibody2

  • Guest
antibody usually has abit of water in the flask ...
« Reply #22 on: June 28, 2002, 10:18:00 AM »
antibody usually has abit of water in the flask when distilling ethers (can never distill to dryness) on a water bath. Then add a couple chunks of NaOH or dry EtOH to the receiver for storage. No explosions yet :) .

weedar

  • Guest
Re:What Chromic said
« Reply #23 on: June 28, 2002, 10:24:00 AM »
I would love to see OTC GHB from this,but of course,safety
first!

Weedar

Weedar contains 2,4-D dimethylamine salt,apparently

Chromic

  • Guest
The other joy of bisulfite
« Reply #24 on: June 28, 2002, 10:42:00 AM »
I awoke today, and looked at my amber glass bottle with THF in it. It was biphasic and filled with crystals! For a second, I thought "shit, this is really fucking bad..." Then a split second later, I realized, oh yeah, I had a added bisulfite to it. Looks like some of the cyclohexanone and acetone crashed out of the THF.  8)  I was just hoping for it to remove the oxygen and prevent formation of peroxides... oh well, onto distillation. (I'm not going to filter out the crystals) I want to get this isolated soon and just store it over a bunch of bisulfite... my interest is gaining in other projects right now. (especially finishing the write up of the peracetic method in DCM as I hasn't done enough testing with asarone and the peracetic and never given a formal write up... and also polishing up a cold water extract on codeine that happens to also remove most of the caffeine... plus changes to the methyl man document... etc etc)

Chromic

  • Guest
Results
« Reply #25 on: June 28, 2002, 11:57:00 AM »
Run down of the results happened:

1. added 3/4 volume of water to pipe cement
2. filtered with cotton, using rubber gloves squeezed out rubber in the cotton.
3. saturate the aqueous extract with salt
4. took off the top organic phase
5. add ~1/3 volume of sat bisulfite sol'n & stir slowly overnight (forms a separate layer)
6. fractionally distill the solution that should now contain the bisulfite adduct (insulate column, go slow). collect between 64-68C. (true bp=66C)
7. check density of distillate, 0.86 (true density=0.888)
8. stored with a bit of sat bisulfite sol'n until use (two separate layers form)

I seemed to have recovered about 30% of volume of the pipe cement as THF.

Chromic

  • Guest
Verifying that this is THF
« Reply #26 on: June 28, 2002, 02:51:00 PM »
Going close to the ratios in

Post 326569

(Chromic: "Calculations for THF =)", Methods Discourse)
, I took 5ml 10.8% bleach (5.7g, 8.3mmol, 1.9 eq) and added 0.35ml THF (0.32g, 4.4mmol, 1 eq). I wanted to use an excess of THF to judge the completion of the reaction on the disappearance of chlorine.

Fearlessly, I added all 0.35ml of THF at once. Nothing happened. Allowed it to sit... ahh, it's getting warm. Then it starts to cool about 10 mins later. The solution is cloudy and smells like chloroform. There are small droplets of an organic phase at the bottom of the test tube.

I tested the sol'n for chlorine by adding a drop of the sol'n to phenolphtalein. It went pink (indicating basic conditions) and stayed pink (no chlorine).

Does THF smell like acetone? What tests can I do to verify that what I have is actually THF?

Chromic

  • Guest
Wait a minute...
« Reply #27 on: June 28, 2002, 04:30:00 PM »
(takes ten steps back) wait a minute... does anyone have any reason to believe that hypochlorite can oxidize THF to GBL in any other conditions than acetonitrile/AcOH? (

Post 3958 (missing)

(Fuchem: "Oxidation of THF to GBL from Tetrahedron Letters", Chemistry Discourse)
)

It appears to me that THF is undergoing a haloform reaction... which is mighty useless to me.

Chromic

  • Guest
« Reply #28 on: June 28, 2002, 05:52:00 PM »
I'm out of ideas. Maybe I'll just drink it as is, my metabolic pathways will take care of turning the THF into GHB, just as they turn GBL into GHB ever so conveniently...


</joking>

Antibody2

  • Guest
What tests can I do to verify that what I have is ...
« Reply #29 on: June 28, 2002, 07:00:00 PM »
What tests can I do to verify that what I have is actually THF? aren't ethers supposed to explode when you add some H2O2?

sorry, you were talking to yourself dude ;)

SpicyBrown

  • Guest
THF stinks!
« Reply #30 on: July 03, 2002, 12:50:00 PM »

Does THF smell like acetone? What tests can I do to verify that what I have is actually THF?




No, THF and Acetone smell pretty different from each other. Don't quite know how to describe the THF smell, except maybe along the lines of a sickly Diethyl Ether-like scent. It REALLY stinks in SWIM's opinion.. If you get a big enough whiff (Not recommended, of course) you can taste the shit in the back of your throat, nasty indeed.

SpicyBrown


Chromic

  • Guest
Ahh...
« Reply #31 on: July 03, 2002, 01:03:00 PM »
This stuff smells like a nasty version of acetone, maybe a bit like diethyl ether... but the smell is not as heavy or as prevalent. Ether stinks up the entire lab when it's used, this stuff doesn't seem so bad. I'm completely convinced now, that THF can't be made by aqueous oxidation using hypochlorite. I believe it can happen using acetic acid and acetonitrile... but I really doubt Cheapskate's THF -> GBL thread.

I too got something salty from the rxn, but I can say, without a doubt, that it was salt.  :)  I should add some GBL and hypochlorite to see if it forms a chlorinated layer as well, I've got little doubt that it's easily chlorinated.

weedar

  • Guest
Oh no!
« Reply #32 on: July 03, 2002, 03:42:00 PM »
Is this the end of theoretic OTC GHB?
(at least for now?)

Weedar

Weedar contains 2,4-D dimethylamine salt,apparently

Osmium

  • Guest
I think people should concentrate on the MBrO3 ...
« Reply #33 on: July 03, 2002, 10:43:00 PM »
I think people should concentrate on the MBrO3 oxidation of THF. Once that reaction is completely understood and gives consistent yields the bleach version will work much better.

I'm not fat just horizontally disproportionate.

riobard

  • Guest
I agree with Chromic on the Cheapskate write-up
« Reply #34 on: July 03, 2002, 11:05:00 PM »
The cheapskate write-up is nowhere as simple as it reads. After swim's toying with batch sizes, parameters, cooling methods, and the all too famous billowing white solids that can't be vac filtered (without special fritted disks or what the fuck ever else one might use besides qualitative grade filter paper), the two of us can only conclude that we should have saved the ACS THF for lithium aluminum hydride reductions like for 2-cb.
     Aqueous methods are wasted time. If i see pool shock again  before i die it will be too soon.
     I'd put a little more faith in that whole procedure if someone could give us a formal write-up INCLUDING A BIOASSAY of the final product. If I'm wrong about what I did, I'd surely welcome a correct path.

Cheapskate, I mean no disrespect. Your contribution in the OTC quaalude synth was, and still is, awesome.

Chromic

  • Guest
Sounds good
« Reply #35 on: July 04, 2002, 09:13:00 AM »
Sounds good, but I'm not sure how many people have access to OTC access to BrO3 (not me). KBr and H2O2, OTOH, are easier to get a hold of. Is there any way to oxidize KBr to KBrO3 using H2O2?

Osmium

  • Guest
UTFSE for 'bromate', this has been discussed ad ...
« Reply #36 on: July 04, 2002, 09:27:00 AM »
UTFSE for 'bromate', this has been discussed ad nauseum.
KBr can be used to make Br2, which is the active ingredient in the bromate oxidation.

I'm not fat just horizontally disproportionate.

Chromic

  • Guest
Let me repeat...
« Reply #37 on: July 04, 2002, 02:50:00 PM »
How do I do this? Would dripping H2O2 into a solution of KBr in water (since bromine is the catalyst, and it could be recycled, this could likely be reduce a bit) with THF and H2SO4, be a smart idea?

Can you give me a balanced set of equations so I can figure out the stoichiometry (ie how many Br2 is required per THF) and an idea of the excess (5%? 10%?) to use so that I could put together a method? Sorry for not using the search engine, but you could have brought me up to speed in half a second.  :)

Rhodium

  • Guest
Equations
« Reply #38 on: July 04, 2002, 08:00:00 PM »
All the reaction equations are actually present in the original paper we discussed a few months ago:

https://www.thevespiary.org/rhodium/Rhodium/pdf/thf2gbl.pdf

- not too common in journal articles nowadays, but in this case they were all there.


Entropy just isn't what it used to be.

Chromic

  • Guest
Ok, but I'm confused.
« Reply #39 on: September 29, 2002, 09:29:00 PM »
I see they used 1 mol BrO3- and 1 mol ether with 1 mol acid in 1L water. How many Br2 is this equivilant to?

The images seem to indicate 1 mol BrO3 can turn 5 Br- into 3 mol Br2? Would this mean translate to using 3 mol Br2 for 1 mol ether? Or just 1 mol of Br2 as is shown in the rxn mechanism for the Br2 oxidation of THF.

Does anyone have an experimental of aqueous Br2 oxidizing THF?

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!