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Author: Subject: Make Potassium (from versuchschemie.de)
NurdRage
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[*] posted on 26-12-2010 at 21:08


Quote: Originally posted by len1  
K floats in paraffin oil alright. I have found it difficult however to get paraffin pure enough so that the improvement in coalesence due to this floating doesnt offset the yield. I cant use nujol this way, its too expensive. After all my tests, coalescence seems a chance event, whats far more constant is the yield, and this is highest in D70. Purification takes about 1/2hr and has to be tollerated


How bad was the yield in your paraffin runs?

Unless the yield is monstrously bad, i'd trade a bit of yield for convenience.

Otherwise, i'd be going after electrolytic methods if yield was my only concern.


Could "used" paraffin with all of the reactive impurities destroyed be recycled into another run for improved yield?
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[*] posted on 27-12-2010 at 00:01


Great work Pok, have you tried making sodium this way too?



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[*] posted on 27-12-2010 at 06:10


The floating does indeed not seem to speed up coalescence all that much: total process times with Nurdrage's IR grade of paraffin were about the same as yours (len1) and woelen's... So maybe it's not worth pursueing as a possible avenue to cut total process time...

[Edited on 27-12-2010 by blogfast25]
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[*] posted on 27-12-2010 at 06:23


I was wrong commenting on ecclectic’s links for the Conoco ‘White Oils’ :mad::

http://www.seversonoil.com/pdfs/FamilyOfBrands/FO_White_Oil....

… there’s a general properties table below the fold, which includes densities, all between 0.827 and 0.875. The grade with the best ratio of (high) density (0.850) and (low) viscosity (2.9 cSt @ 100C) appears to be the 65/75 grade (ISO grade 10/15).
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NurdRage
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[*] posted on 27-12-2010 at 06:26


Quote: Originally posted by blogfast25  
The floating does indeed not seem to speed up coalescence all that much: total process times with Nurdrage's IR grade of paraffin were about the same as yours (len1) and woelen's... So maybe it's not worth pursueing as a possible avenue to cut total process time...

[Edited on 27-12-2010 by blogfast25]


(Btw, i've always wondered why people add "..." at the end of their posts if they don't continue their thoughts.)


Floating doesn't speed up reaction time. If speed is your objective then no, paraffin approach is NOT the way to go.

Although my original intention with testing paraffin was to determine what solvents could be used other than D70.
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[*] posted on 27-12-2010 at 07:08


My experiment with the old Shellsol was not a success. The magnesium hardly reacted at all. The Shellsol had become turbid (white flocculent stuff in the Shellsol) over the few days that it was standing and I assume that the butoxide somehow has decomposed. Probably I also had too little of the butoxide dissolved in the Shellsol.

Probably better results can be obtained if runs are done quickly after each other, but given the long time of a single run that is not a really attractive thing, especially in a home-lab setting, where due to safety concerns one must babysit the reaction all the time.





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blogfast25
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[*] posted on 27-12-2010 at 08:47


Quote: Originally posted by woelen  
My experiment with the old Shellsol was not a success. The magnesium hardly reacted at all. The Shellsol had become turbid (white flocculent stuff in the Shellsol) over the few days that it was standing and I assume that the butoxide somehow has decomposed. Probably I also had too little of the butoxide dissolved in the Shellsol.



I’m not that surprised, the total amount of K t-butoxide (assuming no losses) must be really small.

How about we make some potassium methoxide (or ethoxide), which as I’ve shown above forms easily by dissolving KOH in MeOH. Would the dissolved ethoxide or ethoxide react with magnesium, for instance at BP of the solution? Any formed K would of course react away back to ethoxide and hydrogen…

Would the ethoxide or methoxide be soluble in paraffin based solvents? Doesn’t sound likely…
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[*] posted on 27-12-2010 at 08:56


Quote: Originally posted by len1  
K floats in paraffin oil alright. I have found it difficult however to get paraffin pure enough so that the improvement in coalesence due to this floating doesnt offset the yield. I cant use nujol this way, its too expensive.


I just found this datasheet for Nujol (mentioned by len1):

http://msds.chem.ox.ac.uk/NU/nujol.html

Stated density of 0.752, still below that of K at MP (0.828).


Anyroads, for those in the UK that want to have a go with ‘mineral oil, ‘paraffin oil’, ‘liquid paraffin’, ‘Nujol’, ‘Aboline oil’, ‘Adepsine’ and other stated synonyms, this stuff below is probably your best bet:

http://www.myvetmeds.co.uk/cat/nutritional-supplements-cat/l...

Veterinary ‘liquid paraffin’, 2 l for £6.43…


[Edited on 27-12-2010 by blogfast25]
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[*] posted on 27-12-2010 at 09:35


that's a great find blogfast! I hadn't thought vets also use it. 5 bucks for 1 l is great price.
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[*] posted on 27-12-2010 at 17:27


I had yields of about 50% in paraffin oil, which was dependent on the source of paraffin, I used three types - its not an AR. Due to its large excess, just a small amount of unsaturated, or God forbid -OH groups has a large effect on the yield.

That K floats in whats generally termed paraffin oil is beyond the reach of datasheets. I saw it with my own eyes in two of the oild I used just a few days ago . Key here is the density at 200C

[Edited on 28-12-2010 by len1]
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[*] posted on 28-12-2010 at 06:29


Quote: Originally posted by len1  
That K floats in whats generally termed paraffin oil is beyond the reach of datasheets. I saw it with my own eyes in two of the oild I used just a few days ago . Key here is the density at 200C

[Edited on 28-12-2010 by len1]


Oh, but I don't dispute it: nurdrage's both videos are unambiguous. I just wonder why I can't get it to float even in molten petroleum gel (Vaseline) at 200 C, that's all.

But I won't really be pursueing the paraffin line anymore.
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[*] posted on 28-12-2010 at 09:18


A thought that crossed my mind last night, USP grade mineral oil intended for use as a oral laxative and skin treatment might have to be aromatic free in order to be approved for human use. A low smoke or smoke free paraffin oil may still contain some aromatics, but I would suspect the USP test limits are lower.

I did some searching and noted that CFR 172.878 and CFR 178.3620(a) are the current specifications for USP mineral oil (afaik, correct me if I'm wrong) which mention only test methods and UV absorbance limits, but not hard assay limits (mg/mL, etc).

Side note: I find the test procedure in CFR 178.3620 amusing, the procedure involves copious amounts of isooctane (toxic) and nitromethane (wut?) on a silica column. I guess it is pretty hard to separate out aromatics from alkanes, so they had to resort to some exotic mobile phases.....
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[*] posted on 28-12-2010 at 09:42


Is there some reason, other than cost, than no one has suggested silicone oils? They can have a sp gr around 0.93, are non-toxic, non-flammable, and have high boiling points. It may be possible to find a mass consumer product that isn't prohibitively expensive, like a brake fluid, for example.

Dow provides a lot of technical information, eg:

http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0030/...




The single most important condition for a successful synthesis is good mixing - Nicodem
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[*] posted on 28-12-2010 at 09:44


Quote: Originally posted by Magpie  
Is there some reason, other than cost, than no one has suggested silicone oils? They can have a sp gr around 0.93, are non-toxic, non-flammable, and have high boiling points. It may be possible to find a mass consumer product that isn't prohibitively expensive, like a brake fluid, for example.

Dow provides a lot of technical information, eg:

http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0030/...


Reactivity. Polydimethylsiloxanes would certainly react with alkali metals, especially when molten.

Looks like the hydroxide probably would too...the first page is not showing for me. http://pubs.acs.org/doi/abs/10.1021/ac60271a046

[Edited on 12-28-10 by UnintentionalChaos]




Department of Redundancy Department - Now with paperwork!

'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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[*] posted on 28-12-2010 at 10:26


Yes, what UC said. Also, poor solubility of alkoxides in siloxanes to be expected...
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[*] posted on 28-12-2010 at 10:28


Quote: Originally posted by aonomus  
A thought that crossed my mind last night, USP grade mineral oil intended for use as a oral laxative and skin treatment might have to be aromatic free in order to be approved for human use. A low smoke or smoke free paraffin oil may still contain some aromatics, but I would suspect the USP test limits are lower.

I did some searching and noted that CFR 172.878 and CFR 178.3620(a) are the current specifications for USP mineral oil (afaik, correct me if I'm wrong) which mention only test methods and UV absorbance limits, but not hard assay limits (mg/mL, etc).

Side note: I find the test procedure in CFR 178.3620 amusing, the procedure involves copious amounts of isooctane (toxic) and nitromethane (wut?) on a silica column. I guess it is pretty hard to separate out aromatics from alkanes, so they had to resort to some exotic mobile phases.....


The vet grade paraffin oil suggested above should also be aro-free and cheaper than anything for human consumption.
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[*] posted on 28-12-2010 at 12:51


What is replacement for shell oil?
I think Parraffin is not suitable because has density of >.86
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[*] posted on 28-12-2010 at 14:50


Quote: Originally posted by Waffles SS  
What is replacement for shell oil?
I think Parraffin is not suitable because has density of >.86


Please read the thread, Len1 and I have already proven paraffin to work. Although yields with "domestic" paraffin sources are ~50%, which lower than with Shelsol D70.


=================================

@ everyone else

More negative results: (They say all results are "data" after all ;) )

PEG-3350 as a solvent --> Catches fire! About 3 minutes after melting the reaction vessel spontaneously ignited and the magnesium and PEG burned together yielding a sponge-like mass of carbon with KOH embedded in it. Messy, but no loss of glassware and safety measures including bubblers and back-flow arresters completely contained the flames. Was fun to watch. I wish i filmed it.

Brake Fluid --> since brake fluid (DOT 3) is essentially shorter chain PEG i decided against directly testing this. I think the PEG-3350 results still apply.

PEG-3350 as an activator/catalyst (in paraffin solvent)--> Failure, hydrogen evolution stopped 20 minutes into the run and subsequent testing with water showed no pops or fizzes associated with even minute potassium production.


Before anyone complains that this was a waste of time and would have never worked in theory anyway I'll say my objective is to test theories. :D
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[*] posted on 28-12-2010 at 17:04


Exxon Isopar L seems to be fairly close to Shellsol D70:

http://exxonmobilchemical.ides.com/en-US/ds128997/Isopar%E2%...

http://www.westmarine.com/webapp/wcs/stores/servlet/Product_...
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thumbup.gif posted on 29-12-2010 at 08:04
Synth. of t-alcohols thread in ‘Organic chemistry’ section


In agreement with nicodem a thread has now been started in ‘Organic Chemistry’ to generate knowledge on the synthesis of t-alcohols, in particular longer chain ones:

http://www.sciencemadness.org/talk/viewthread.php?tid=15171#...

May it too become sticky soon!:cool:
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[*] posted on 29-12-2010 at 14:26
AWESOME results with tetralin


Once again i was back at it verifying "negative theory". I know it seems like a waste of time, but good science uses theory as guides for experimentation, not substitutes.

Tetralin wasn't supposed to work since it was aromatic, but since i had lots of it (for making lithium sand) i thought i'd try it anyway. I figured if it could stand up to molten lithium it should stand up to molten potassium.

Anyway, When I did it I didn't make accurate measurements since this was a qualitative experiment and just kinda eyeballed the reagents since i had done it a dozen times already. I did the usual dehydration step and popped a shot of alcohol. Then i heated the solution to vigorous reflux and walked away for 1 hour while i tended to other things.


Came back and saw:



Potassium in Tetralin.jpg - 26kB

I wasn't expecting this so i wasn't filming it, needless to ssay i was :o :o :o :o :o


Anyway, the reaction is FAST, in just one hour it went to completion and gas evolution stopped. It might even have taken less time since i wasn't monitoring it for an hour. Perhapes the crudely eyeballed amount of t-amyl alcohol used might be the bigger contributor to the rate so i'll try again under more quantitative conditions later.

Since tetralin is so dense (0.97g/mL) floating coalescence took place and i got all the potassium crammed into one ball like with my paraffin runs. Despite the vigorous reflux the ball still maintained cohesion.

So with tetralin we're getting the advantage of HD paraffin of floating coalescence without the disadvantage of longer reaction times.

I'm not certain about the yield yet, since i didn't accurately measure anything when i started. Like i said i'll do a quantitative run later.

Now i know not everyone can get their hands on tetralin but i think the bigger result here is that aromatics can work. So we don't need to go out of our minds to hunt down perfectly aliphatic solvents. Since aromatics tend to be denser we might have an easier time brewing up some floating coalescence capable solvent mixtures.

On a different note, this also highlights the good practice of verifying all assumptions and theories with hard data or citable sources using exact conditions. Occasionally we might uncover diamonds :D

I guess Woelen needs to update his page ;)
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[*] posted on 29-12-2010 at 15:30


I am interested if anyone tried this?


Quote: Originally posted by Jor  
Now this would be a very interesting way to make lithium, but it's really a bummer that lithium has such a low molecular weight, making it impossible to make acceptable amounts of lithium.


Also, a little off topic though,may LiOH be collected/synthesized from worn out Li ion laptop batteries?
This may be a cheap source for Li compounds...






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[*] posted on 29-12-2010 at 16:44


Awsome results Nurdrage, am I correct in assuming that what I see there on the top that looks shinny is Potassium? If so then that looks very lovely.

I wanted to ask and sorry if it was already but has anyone considered the use of Cyclohexanol? I would think, even more so now that the alkoxide of it would be more soluble in paraffin oils and higher boiling point as a short chain alcohol. At 160 degree Celcius boiling point I would think its use would be well suited here.





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[*] posted on 29-12-2010 at 17:11


yeah, the shiny metal "island" in the flask is actually the top of a single large ball of potassium.

As for your cyclohexanol question; since it's a secondary alcohol i think it wouldn't work. Isopropanol, another secondary alcohol, was already tried in this thread and that failed miserably.
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[*] posted on 29-12-2010 at 17:58


1-ethylcyclohexanol from ethyl bromide and cyclohexanone might be interesting to try.
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