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Author: Subject: Ketone distillation at atmospheric pressure
conducter
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[*] posted on 27-12-2006 at 15:30
Ketone distillation at atmospheric pressure


at the hive swim found this

Chromic
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11-09-03 14:18
No 469860

MDP2P

"SWIC has seen MDP2P distilled without a vacuum at 283C (made from oxone and from peracetic routes)... but don't expect the teflon on the stir bar to last for long, ensure everything is very insulated with glasswool (inc. the clamp), and your yields will be down about 10% on the recovery of the ketone...

So by comparison, 200C is rather light heating... but again, make sure you use glass wool insulating everything, including the clamp. The stir bar will be discolored... but not destroyed."

Is this really possible, swim is terrible and cannot for the life of him figure out what type of pump/aspirator to get and how to not explode his distillation setup so he wants to try to distill the ketone at atmospheric pressure.

Would a chaser liquid be a good idea? to keep the mdp2p from charring in the flask to polymerized crap.
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Baphomet
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[*] posted on 28-12-2006 at 20:03


It would need to be very pure ketone.. and your 'chaser' had better be a high boiling point and pure as well.. otherwise polymerisation is bound to occur. Why do it this way with all the insulation and ruined stirrers when you could use an aspirator? I've never seen a setup implode when using aspiration btw.
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[*] posted on 28-12-2006 at 21:46


Vacuum is vacuum no matter the source. Whether or not your glassware implodes would seem to be a function of 1) glassware design, i.e., whether or not it is designed for full vacuum, and 2) whether or not it has any defects, i.e., "stars," etc.

I would think it would be just good practice to bring up a vacuum slowly, thereby minimizing any additional stress due to dynamic conditions.




The single most important condition for a successful synthesis is good mixing - Nicodem
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Baphomet
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[*] posted on 29-12-2006 at 02:23


Sure glassware makes a difference but so does the vacuum source. An aspirator at 20 kPa is less powerful than a vaccum pump at 5 kPa
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[*] posted on 29-12-2006 at 11:38


Quite a risky operation IMHO...

I'd use a vacuum distyllation without any question. Basing on theoretical nomogram the bp would be about 120 C if the pressure is , say, about 25 torr (casual water aspirator with all hydrawlic resistances inculded).

At 1 torr it should be about 80 C...
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MargaretThatcher
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[*] posted on 29-12-2006 at 13:35


Quote:
Originally posted by Baphomet
Sure glassware makes a difference but so does the vacuum source. An aspirator at 20 kPa is less powerful than a vaccum pump at 5 kPa


Let's stick to scientific terms. The vacuum pump has a pumping speed and limiting pressure. With a closed distillation set, the pumping speed is not relevant - even a water-jet pump is capable of reaching its limiting pressure, the vapour pressure of water, with such a small volume.

The stress in the flask depends on the pressure differential, i.e. between atmospheric 100 kPa and the vapour pressure of the ketone at whatever the distillation temperature is. Whether you are distilling with an aspirator at 1 kPa or a rotary pump at 0.5 kPa, the differential is still close to 100 kPa. The flask stress is the same, and the vacuum source will have no effect on whether the glass implodes, as Magpie says.




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[*] posted on 29-12-2006 at 23:29


steam my friends it works every time and all at just over 100C no polymerisation.
is that who I think it is or are you taken a nick like some one who took quantum.
if so whats goen on many rummors. if not thats realy wrong man especialy that one.




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[*] posted on 30-12-2006 at 13:08


Substituted ketones dont steamdistill easily or at all.



Irgendwas is ja immer
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[*] posted on 30-12-2006 at 18:39


md does :) not too easy but hey it dont char just takes time. use a large sep as your reciver with DCM in it. stir before droping solution out of funnel. having said that probably better to use a floating NP but never tried it.



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conducter
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[*] posted on 31-12-2006 at 17:09


why have dcm in the receiver? was just gonna have a flask in an ice bath as receiver.

Also im wondering,i was inquiring about a Chapman Aspirator and was told it is totally satisfactory for mdp2p distillation.

the only worry is do ALL SINKS fit aspirators? or do you have to modify it, and if so how?

[Edited on 1-1-2007 by conducter]
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MargaretThatcher
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[*] posted on 1-1-2007 at 16:09


Quote:
Originally posted by conducter
the only worry is do ALL SINKS fit aspirators? or do you have to modify it, and if so how?

[Edited on 1-1-2007 by conducter]


You may be lucky in having an aspirator that will screw directly to the tap. More more likely not, in which case you will have to plumb something together. You will also be flushing hundreds of gallons of drinking water down the drain every hour. Very wasteful. Better to rig up a closed circuit system with pump. You can add ice to keep the temperature down and so improve performance.




The reformative effect of punishment is a belief that dies hard, I think, because it is so satisfying to our sadistic impulses. - Bertrand Russell
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[*] posted on 1-1-2007 at 23:08


if one was in such a position where they did not have vacuum or aspirator avaiable... and just finished a wacker oxidation.
The ketone collected in DCM washed with saturated sodum bicarbonate solutions, saturated nacl solutions, and 5% naoh solution, then distiling off the DCM to leave the impure ketone.

If this was used directly in an al/hg amalgam would the ratios go up from say 25g mdp2p to 30g of the impure mdp2p?

i believe that whatever ketone IS there will be reduced and then recovered as mdma while the impurities are broken down in the al/hg or simply washed out in the workup. Can anyone verify that this could be done in a pinch?
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[*] posted on 2-1-2007 at 02:24


Quote:
if one was in such a position where they did not have vacuum or aspirator avaiable... and just finished a wacker oxidation.
The ketone collected in DCM washed with saturated sodum bicarbonate solutions, saturated nacl solutions, and 5% naoh solution, then distiling off the DCM to leave the impure ketone.

Ok, my opinion on the matter: If you don't have the equipment then you don't make materials intended for human consumption. Poisoning yourself is stupid, poisoning others makes you a big asshole. The fact that the material you want to make is commercially available makes it even worse. You don't save money at the expense of other people's health. Period.

The wacker oxidation does not only give MDP2P, but also the propanal and probably other ketones. You have to remove them by distillation (or chromatography).
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[*] posted on 2-1-2007 at 13:35


If you don't have a vacuum pump, make one. I think frogfot has a post here somewhere on how to make a water-jet pump. I made one with a 1" threaded t-piece, some screw-in reducers, epoxy and some brass tubing from a model shop to see whether it would work, and by god it did! Just as well as a commercial one.



[Edited on 2-1-2007 by MargaretThatcher]

[Edited on 2-1-2007 by MargaretThatcher]




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[*] posted on 4-1-2007 at 04:57


id like to see the writeup, is that picture of an aspirator? i have no problem getting an aspirator but just finding a sink that actually will connect to it is hard. Some will say make the ghetto condenser in a bucket and hot tub pump to retun water to the bucket, but isnt that a little expensive? not to mention that the part about the "baffle" confuses the hell out of me.
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[*] posted on 4-1-2007 at 09:44


What you need is a faucet that will connect to the aspirator. Most convenient is a faucet with a threaded spigot. From there you can get adaptors that will connect you to the threads on your aspirator. If the faucet you presently have is not threaded then get a new one. You also want to be sure that your sink is deep enough for the aspirator as installed.



The single most important condition for a successful synthesis is good mixing - Nicodem
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[*] posted on 4-1-2007 at 10:06


I found a 'faucet-to-garden hose' adaptor, as well as a 'garden hose-to-3/8 in ID' connector at my local brew supply store.

The bottom part of my faucet unscrews (I didn't realize this at first), then I can screw the adaptors on. I then connect 3/8 in ID tubing to these, and this fits my aspirator.

Until I figured out that I can remove part of the normal faucet, I was lost.
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[*] posted on 4-1-2007 at 10:34


finally, pantone, someone who knows the trouble im going through.
i have an aspirator let me describe to u...

The body is a nickel plated white metal and the baffle tube is manufactured from aluminum. The water inlet connection thread is a standard 3/8" NPT taper.

Specifications:
Vacuum Inlet:
10 mm / .385"

Water Outlet:
10 mm / .385"



Length:
137 mm / 5 3/8"

Vacuum generated @ 30 psi
29.5" Hg



At a water pressure of 30 psi this aspirator will reduce atmospheric pressure by 29.5" Hg.

Standard pressure 29.92" Hg = 1 atm
- 29.50" Hg
Net pressure = 0.42" Hg = 0.014 atm


This is from the manufacturer, im not sure what it all means but is it good enough to distill high boiling ketones that would normally come over at 280C at atmospheric pressure?

I think i know what i have to do, find the sink which i will distilling next too, setup shop there. Then unscrew the faucet aerator, take it to the hardware store and ask them for a thread adapter and give him the aspirator to hook up for me.
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[*] posted on 4-1-2007 at 11:49


There is a bid thread running into 4 pages on homebrew aspirator

http://www.sciencemadness.org/talk/viewthread.php?tid=437#pi...

Tacho and several other members have made very useful contributions there. Why not refer to it ?

gsd
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[*] posted on 4-1-2007 at 11:51


the aspirator isnt the problem, its figuring out if its strong enough and how to hook it up to the sink
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[*] posted on 4-1-2007 at 14:15


I think your aspirator is fine. Remember, 30"Hg is a perfect vacuum and you can't do better than that. Even if you had the most perfectly designed aspirator money can buy you cannot get an absolute pressure less than the vapor pressure of your motive fluid, in your case water. In the winter my aspirator gets me near 27"Hg. That is plenty to get the boiling point down to where you need it for most organics IMHO. For example, it will boil water at room temperature.

Your plan to take the aereator and the aspirator to the hardware store is perfect. I believe my aspirator required 2 adaptors, hard piped, no tubing. If you find the right guy at the hardware store (one that knows plumbing) he'll fix you up.




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[*] posted on 4-1-2007 at 14:41


And always run the coldest water i can through the aspirator right? Also what kind of tubing would be best for this if vacuum tubing isnt able to be ordred? I think i remember the guy saying something abut a plumbing store selling black vacuum tubing but im not sure.
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[*] posted on 4-1-2007 at 15:54


Yes, cold water as it has a lower vapor pressure. I ordered vacuum tubing out of a scientific supply house but any thick walled tubing that won't collapse on you will do. If the hardware stores don't have it check an industrial supply place selling hose. Automotive parts places may have it also.

[Edited on 4-1-2007 by Magpie]




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[*] posted on 4-1-2007 at 19:41


How do i secure the vacuum hose to the distillation adapter and aspirator? Those little plastic ring ties? or tape or what
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[*] posted on 5-1-2007 at 16:57


Standard thick walled rubber vacuum tubing should push fit both ends OK without leaking. You'll have to improvise based on circumstances. Yes, you want cold water for best limiting vacuum. If you build a recirculating system, you can freeze bags of water and float ice blocks to cool it all down. Abolt on The Hive used to do that.



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