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Cyrus
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[*] posted on 1-7-2004 at 12:55


Ok, I changed the design slightly- if you can decipher the poor image from the charcoal furnace thread, the Na ought to condense into a liquid in the pipe and run into the molten paraffin.



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ordenblitz
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[*] posted on 15-8-2004 at 10:39


It has been pointed out that dillutents like sodium silicate, sodium chloride or Magnesium oxide can or have been added to the NaOH / Mg Thermite reaction to slow it down.
I was thinking that there could by a variety of coolants that might function better for this application. One that comes to mind is magnesium carbonate. Besides cooling it should also create a blanket of gas to protect the sodium as well. Also might one try consolidating the mixture by compression before ignition to slow it down thereby making it easier to collect the sodium vapor?
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[*] posted on 2-9-2004 at 14:20
Sodium (and others) from Halide salt reduction with CaC2


According to US patent 4,105,440, CaC2 reduces alkali/earth alkali metals when their salts or eutectic mixtures are molten, and CaC2 is added to it.
I guess this is only feasible if you have a furnace or similar, as high temps (betw. 700 and 1000 deg C) are required.

The reaction is

CaC2 + 2MeX ---> CaX2 + 2 me + 2 C (finely powdered graphite).

X is a halide, i.e. Cl, Br, and Me is the alkali metal.

I am not quite sure how to extract the (i.e. Na, Ba) from this, I haven't read the patent to the end, but just wanted to add this to this thread for completeness' sake.

[Edited on 2-9-2004 by chemoleo]




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[*] posted on 2-9-2004 at 17:17


But, surely, a problem in that patented process, if it is genuine, would be reaction of the alkali metal produced with the graphite byproduct to form an alkali metal carbide? The only way this could be overcome would be by rapid removal of the Na as the vapor (above its boiling-point at the reaction vessel pressure), to be condensed elsewhere, as soon as it is formed. In fact, the whole scheme, involving displacement of Na (more electropositive) by Ca, would be an equilibium reaction depending on volatility and removal of the Na vapor for its success.

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[*] posted on 2-9-2004 at 17:28


No, it is not a simple displacement because your starting point isn't Ca, it's CaC2! It's not just a thermite reaction, using Ca instead of Al!

As to genuineness, read the patent and judge for yourself, before speculating.
As to isolation, Mg can be made this way, and it doesn't seem all that difficult - apart from the heat and the necessity of a protective atmosphere. But then the Mg can be simply decanted off... isnt that cool?

[Edited on 3-9-2004 by chemoleo]




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[*] posted on 2-9-2004 at 17:47


Very true, this is very similar to the reaction that I have seen that Dupont used to use for the production of sodium.

Quote:

The Dow Chemical Co. has recently patented a process for producing sodium by distillation of a mixture of carbon and sodium carbonate fused in an electric arc furnce at 1200 C [224]. The sodium vapor is condensed by rapid chilling in a lead alloy, containing 5-15% of sodium, at 375-400C. Part of this quenching liquid is continuisly withdrawn to a still in which the sodium is removed at 600C. Good efficencies are claimed by the Dow Co. for this process. Similar processes use high-frequency induction furnaces for the reduction of sodium compounds by granular graphite [26], of for the reduction of sodium chloride by lime and coke [212]. Calcium carbide has been proposed as a reducing agent [65]...

[26] B.P. 486930
[65] French P. 828712
[212] U.S.P. 2200906
[224] U.S.P. 2391728


Quote:

The thermal reduction methods in general utilize carbon or a carbide as the reducing agent. [22]

6NaOH + 2C ---> 2Na2CO3 + 2Na + 3H2

A mixture of rubidium chloride or cesium chloride with calcium carbide heated to 700-900C in vacuo gives a 75% yield of the alkali metals. [23] With sodium chloride a temperature of 950C is used. [24] The production of potassium is reported using silicon or calcium carbide as the reducing agent at a temperature of 100-1150C.

2KF + CaC2 ---> 2K + CaF2 + 2C

Part of the KF may be substitued by K2CO3 or K2SiO3 without any loss in yield.

2K2CO3 + 3Si + 6CaO ---> 4K + 2C + 3(2CaO*SiO2)

These methods usually require good vacuums at high temperatures.

[22] G.L. Putnam, Ind. Eng. Chem. 30, 1138 (1938).
[23] V.D. Polyakov and A. A. Fedorov, J. Applied Chem. (USSR) 13, 1833-8 (1940) [C. A. 35, 5049 (1941)]
[24] P. V. Gel'd et al., J. Applied Chem. (USSR) 20, 800-8 (1947) [C. A. 42, 4478 (1948)]


From "Comprehensive Inorganic Chemistry".

BTW, sodium carbide is only stable up to 400C, therefore removal before reaction is not a problem, same with hydrogen, sodium hydride is only stable upto a lower temperature, it can safely be held under a hydrogen atmosphere in a Castner cell without reaction, it maintains a mirror sheen to it in such a case.

Ohhhh... I'm posting this without spell checking it, bad boy, bad! :D

Edit: Spelling.... ;)

Oh, and... Cyrus
Quote:
Na vapors will bubble into molten paraffin.


Run the vapors into a copper spiral condenser immersed in heated mineral oil to the melting point of sodium, the sodium will condense and the liquid sodium can run into your paraffin :D

[Edited on 9/3/2004 by BromicAcid]




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[*] posted on 5-1-2005 at 12:18


I have just received a book through Ebay, signed by Miss Phebe E. Travis, (Cou/nton?+ something I cannot read) Sept. 28th. 1857.

Preparation of potassium.
(a quick search has not shown anything similar)
My typing is not to good but here goes.

The expensive and troublesome method of procuring this metal by galvanism, has been replaced by a much more convenient and productive furnace operation, founded on the decomposition of potash at white heat by charcoal. For the pupose carbonate of potash is mingled with charcoal. This mixture is best prepared by ignited cream of tartar in a covered crucible; a black mass is then obtained, commonly known as black flux, consisting of carbonate of potassa in intimate mixture with charcoal derived from the burning of the organic acid. This mass is finely powdered, and 1/10 of charcoal in small fragments is added. The mixture is then placed in an iron bottle V ( fig. 348) laid horizontally in the furnace. The bottle should be about 3/4 full, and well protected with a refractory lute of 5 parts fine sand and 1 part fire-clay, laid on moist, and well dried in the sun.
(If anyone is interested I can copy the diagram and post it)
The cover of the furance (M) admits the fuel, the draft (O) is regulated by a damper, and a temporary front (r,n) closes the side-opening. A short iron tube (a,o) connects the retort with a copper condensing chamber (A, B, C) containing naphtha, and supported on (T, P S, from diagram). The heat is gradually raised to the most intense whitness. Decomposistion of the carbonate of potash ensues, the free carbon takes the oxygen of the carbonate, carbonic oxyd is evolved, and the potassium distils over in metallic globules, which condense in the receiver (A).

The receiver is made of copper and the potassium is collected under naphtha. It also tells you that one of the pipes can become blocked and how to keep it clear.

The comment about sodium is that it can be made the same way as potassium

mick

Some of the spelling mistakes above are not mine, I copied them.

Edit mick

[Edited on 5-1-2005 by mick]
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[*] posted on 1-5-2005 at 12:01


10 grams of potassium hydroxide was mixed with 5 grams of magnesium metal and placed into a pipe with a one way gas exit ball check valve. The mixture in the pipe was heated from the bottom with a propane torch and after a few minutes a reaction commenced evidenced by a popping sound from within the container, upon hearing this the exit gasses were ignited and they burned for a mere thirty seconds. Heating was continued for fifteen minutes and discontinued.

After an hour the vessel was opened and after removing the cartridge portion the upper half caught on fire (possibly from potassium that condensed therein). Gobules of potassium were at the bottom of the vessel but for the most part there was a tower of unreacted material in the middle (should have incorporated my KOH with my Mg better). A gobule was removed with a metal rod, it came up cleanly, potassium.... And ignited, actually everything ignited, even cold it seemed to be quite reactive. I dumped out the contents, there were areas of grey at the bottom and green areas in the matrix, from what I don't know. When the 'gunk' at the bottom was broken apart there was small amounts of potassium in the matrix.

Allow me to reenerate that I do these reductions between magnesium and potassium hydroxide because literature states (as do experiments by other members) that the reaction between NaOH and Mg is violent. So next time I have to remember to pour in mineral oil before I start poking around in the reaction products.




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[*] posted on 18-6-2005 at 16:18


After reading the unconventional sodium thread again last night I decided to test my idea of using magnesium carbonate as a coolant to slow the reaction of either NaOH +Mg or KOH+Mg down so as to be able to better collect the vapor.

I ground, under argon in a mortar and pestle, 5.6gm KOH then added 2.4gm Mg as -200 mesh granular powder.

http://img98.echo.cx/img98/4996/200maggrnd8vb.jpg

Before adding any MgCO3 I wanted to get an idea of just how fast this mix would combust without any coolant. So I put a .05gm +or- on a spatula and passed it into a flame. It didn't really impress me. So I placed roughly .1 gram in a 25 ml erlenmeyer touched it off with a loop of hot nichrome.

http://img98.echo.cx/img98/5171/25mlerl6hk.jpg

This time it was even more sedate, burning rather slowly and in a controllable manner. Since it happened much slower in the flask, under argon then did the small amount I burned in the open. I figured atmospheric oxygen might be having a greater effect then anyone had guessed. Was a coolant even needed?

Looking at the reaction: NaOH + Mg --> MgO + Na + 0.5H2
There isn't much hydrogen generated and so it might be possible to totally confine the combustion and greedilly capture all the alkali thus produced.
I remembered that a while ago, I picked up an old Parr oxygen combustion bomb kit from LabX for almost nothing. It has since been gathering dust waiting for something to do.

http://img98.echo.cx/img98/4245/parr0ee.jpg

Same as above, I ground 1.12gm KOH with .48gm Mg under argon and loaded it into the parr bomb. I threaded 7cm of nichrome on the studs and capped it while still in the inert atmosphere. Not knowing exactly what would happen I took it outside and placed the aptly named "bomb" behind two steel blocks, connected the wires and made a hasty retreat. I pressed the button and nothing…. not a whimper. Disappointed I approached the bomb and touched it and to my surprise it was warm ~90c.
I let it cool in the freezer for a bit and then used the wrenches to crack the top. There was only a weak little hiss as my .02014 grams of hydrogen escaped. I placed the bomb in mineral spirits to finish the opening and let the contents flood. The interior was remarkably clean and most of the contents had stuck together in one porous chunk. The MgO probably floated on the potassium, that more or less pooled to the bottom of the steel cup. I dumped the contents and poked around a bit to see what was what. You can see in the pic which end of the chunk was down.

http://img98.echo.cx/img98/9708/allres1li.jpg

I will try an even larger quantity tomorrow and probably tap the bomb while still hot, in an attempt to consolidate the hot metal into one lump. Then I will try it all again with sodium.

I don't know if it really is necessary exclude all oxygen in the bomb but it probably does help in keeping the combustion pressures lower. I think I should try a smaller load, with normal atmosphere to see.

One could probably cobble together a suitable combustion chamber out of commonly available materials. The wire pass through might be a problem. I think it's a phenolic sleeve on the Parr.
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[*] posted on 19-6-2005 at 04:24


I think if you are happy to swap magnesium metal for sodium or potassium its worth reading US4725311.

The patent was dug up by someone who has since removed all his posts. Its a way of achieveing the same result without making close relatives of flash powder mixtures and setting them off inside sealed containers. I like the look of the solvent method a lot and plan to try it when I get some cheap block magnesium. I would be inclined to wonder if you had diluted with magnesium carbonate if that would have been reduced by the magnesium itself. I have the nasty feeling that would have been a rather better flashpowder what with the effect of carbondioxide on magnesium fires.
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[*] posted on 20-6-2005 at 17:08


Yesterday, I decided to try making sodium using the pressure bomb method. I wanted to see the difference between Na and K when reacted with Mg in an inert atmosphere. Some have suggested that Na + Mg makes a near flash powder. But just as my potassium experiments showed the previous day, that only seems to happen out in the open and not in a negative oxygen environment.

2.43gm Mg + 4gm NaOH were ground to a fine powder in a mortar and pestle while under argon. A small amount ~.1 gm was transferred to a small flask that had been flushed with Ar, placed in a hood and lit with a hot wire loop. It was not much more impressive than my similar KOH+Mg experiment.
http://img208.echo.cx/img208/9361/naohmgar2kw.jpg

On to the confined reaction… I placed ~2gm of the above NaOH+Mg mix in the parr bomb and sealed while under Ar.
http://img208.echo.cx/img208/7578/fillparrna5vh.jpg

This then was wired up and set out to fire. I still use the blocks even though from the outside, nothing much seems to be happening. Picture taken 30 seconds after ignition.
http://img208.echo.cx/img208/962/nabmbsetup8zl.jpg

After allowing the bomb to cool for 10 min or so, I cracked the seal while waiting for a hiss of escaping hydrogen but none was heard as before in my K experiments. Very interesting I thought, where had it gone? The contents after opening under mineral spirits and washing with 1, 4 dioxane, were very different then the potassium experiment. You can see light and dark silver/grey and blue coloration.
http://img208.echo.cx/img208/51/indioxane6md.jpg

Sodium hydride.
Merck says: prepared by passing hydrogen into molten sodium dispersed in oil or mixed with a catalyst such as anthracene above 250º. Reacts explosively with water, violently with lower alcohols, ignites spontaneously upon standing in moist air.
So this method isn't going to work if one is after solid sodium metal but I think it has promise for potassium since it does not form hydrides in this reaction. I am still working on improving the Kbomb and will post the further results as I have them.

The upper layers in the parr cup were lighter in color and certainly contained a greater percentage of MgO and were a brittle crunchy mass. The lower layers were more metallic yet not like sodium is supposed to look. The picture is of the solid upper mass that came out of the cup.
http://img208.echo.cx/img208/3686/wetchunk0gb.jpg

Upon tossing the chunk into water this is what happened.
http://img208.echo.cx/img208/479/uplayerinh2o5no.jpg
Not nearly as fun as what happened when small portions of the lower layer were tossed in.
http://img208.echo.cx/img208/6785/lowlayerinh21gb.jpg

For those who don't happen to have an oxygen combustion bomb lying around, one could make a heavy metal, threaded capped tube and drill and tap one end for a small spark plug. One could then attach a fine nichrome wire between the center electrode and the ground tang. Voila instant reaction chamber.

Marvin, of course I would trade magnesium for K or Na since I have plenty of Mg lying around and none of the latter. I read the patent you referenced and thought I might try a small version in test a tube and see if it might work. I placed a stoichiometric mix of NaOH + Mg in heavy mineral oil and began heating. The contents did become very frothy and I continued this heating for roughly 20 minutes. After that time I added a few ml of 2-propanol as a catalyst as suggested in the patent. I continued heating for another 30 minutes. After heating the contents settled and no visible difference in the magnesium was noted. I washed the contents on filter paper with 1,4 dioxane and tossed it into some water looking for any reaction. There was none. It's possible that the mineral oil interfered or the reaction times were too short.

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Marvin
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[*] posted on 22-6-2005 at 06:32


I think for any reasonable preperative amounts that reaction is going to be difficult to handle even aside from problems extracting the sodium or potassium product.

Treat the process in the patent more like a grignard reaction. Started with an iodine crystal or two a dry alcohol will devour magnesium until one or the other runs out, when this starts its obvious and the rest of the reaction should follow. I'm not certain what you mean by mineral oil but it needs to dissolve the alkoxide and be able to reflux at a fairly low temperature. I'd be inclined to follow the process as closely as possible for the first few tests. The only major aggro with this method seems to be seperating the metal from magnesium oxide in the ingot in the end, hense the trickery with controlling the density of the solvent on some of the examples.
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[*] posted on 23-6-2005 at 11:38


This is Winkler's 14 page article, published in 1890. It presents several Mg reduction experiments. He seems to have had good results with potassium, as has been mentioned before. From Gallica.

Any highlights worth translating?

Attachment: ber_23_44_1890.pdf (808kB)
This file has been downloaded 2752 times

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ordenblitz
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[*] posted on 23-6-2005 at 18:09


Can anyone who has read the above tell me what procedure was used in the separation of the MgO from the K.
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[*] posted on 24-6-2005 at 04:16


@ S.C. Wack: Wow, that is very interesting! I'll translate some parts of it when I have time (need to go now).
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[*] posted on 25-6-2005 at 02:29


- They use magnesium for the reduction of alkali metal compounds, the compound and magnesium powder are first dried and then ground together in a mortar. Then the mixes are heated in a glass tube sealed at one end. A test to the behavior of the mix is first carried out with very small amounts.

-The heating of a mixture of 74 parts Li2CO3 and 72 parts Mg produces a violent reaction, and the glass tube is usually shattered.

-Heating a mix of 106 parts Na2CO3 and 72 parts Mg produces a yellow flame from the glass tube, and the inside of the tube becomes coated with a mirror of metallic sodium. All the sodium is vaporized from the mixture because of the heat of reaction.

- Heating a mixture of 138 parts K2CO3 and 72 parts Mg produces no vigorous reaction, but it still reacts and the inside of the tube becomes coated with a mirror of metallic potassium.
The potassium can be isolated from the reaction mixture by conducting the reaction in a glass tube which is open at both ends and after reaction distilling off the potassium (bp 667°C, easily reachable with a bunsen) in a slow stream of hydrogen. The potassium vapor is green and coats the inside of the tube with a mirror in the cooler parts.

The mentioned stochiometric composition of the K2CO3/Mg mix must be correct and the components have to be mixed thoroughly, otherwise, expecially when there is a lack of magnesium, Kohlenoxydkalium (the potassium salt of hexahydroxybenzene/dihydroxyacetylene, a grey dust) forms, which is highly explosive and very dangerous.
The mix also must be heated rapidly and not gradually, also to prevent the formation of this dangerous compound.

The production of potassium from KOH and magnesium is more convenient. The KOH must be dehydrated before use by melting and heating it to red glow for some time.
56 parts of this are mixed with 24 parts Mg and heated in the glass tube, the reaction is more vigorous than with K2CO3, but no carbon is formed and, more importantly, Kohlenoxydkalium cannot form.
A large portion of the potassium is evaporated from the reaction mixture by the reaction heat, the rest can again be separated by distilling it off in a stream of hydrogen (this sounds more difficult than it is- simply do the reaction in a glass tube, after the reaction slowly let in dry hydrogen from one side and heat the mirror and the reaction mix and the K will distill off to form a clean mirror, the K can be collected by dipping the mirrored part of the tube into hot paraffin oil to melt the K).
Doing this Reaction on a larger scale is dangerous because of the vigor of the reaction, but it can be moderated by mixing in some MgO, and using a mixture of 56 parts KOH, 24 parts Mg and 56 parts MgO is without any danger, even on a large scale (kilograms).
The potassium remains in the reaction mixture and can be conveniently distilled off by the method mentioned above.

- Production of rubidium from the carbonate is as easy as potassium from the hydroxide, but the reaction is much slower and less dangerous. The Rb can be distilled off in a stream of hydrogen.
Reduction of RbOH is even easier.

- Reduction of Cs2CO3 with magnesium is not possible, even at temperatures where the Mg begins to evaporate. Only traces of K and Rb vapor are given off, which might be a method for purification of Cs salts from these contaminants.

@ S.C. Wack: I posted a link to your attachment in a german forum, don't be surprised if the download counter goes up.
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[*] posted on 3-7-2005 at 18:21


I like the patent that Marvin posted, especially since I have a bunch of blocks of Mg. Since I was involved long ago in a galaxy far away with work on electroink processes, I know the chemistry of liquid toner copy machines very well. The question being since the dispersants used in say the Savin (TM) line of liquid copy machines are probably the most highly refined and pure isoparaffins you can buy, and quite easy and cheap to obtain, would simple copier dispersant be suitable for use in the process? Looking at the patent they were showing 92% purity mixed with other things, and it seems to me the more pure a substance is the better the process. Has anyone thought of using this source for the solvent?
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[*] posted on 18-7-2005 at 06:54


I've caught the Na/K bug again. I'd like to try the Mg + K2CO3 method, except for this "Kohlenoxydkalium" problem. Since this stuff has H in it, I was wondering if its formation could be prevented by not using H2 gas, but CO2 or He, or a vacuum. I like the idea of a vacuum because Na and K volatize somewhere around 250-300 C (O. C. Braur's Prep. Inorg. Chem.) which would probably be obtained just by the reaction's heat. So there would be no messing around with H2 and no secondary heating.

~
The mentioned stochiometric composition of the K2CO3/Mg mix must be correct and the components have to be mixed thoroughly, otherwise, expecially when there is a lack of magnesium, Kohlenoxydkalium (the potassium salt of hexahydroxybenzene/dihydroxyacetylene, a grey dust) forms, which is highly explosive and very dangerous.
The mix also must be heated rapidly and not gradually, also to prevent the formation of this dangerous compound.
~




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[*] posted on 30-10-2005 at 12:46
Following US patent 4725311


[Note, the amounts that I used are accurate to within plus or minus 1 gram, due to my scale only reading to the gram level]

16 grams of potassium hydroxide was placed into a 250 ml erlemeyer flask along with 175 ml kerosene procured from my local gas station. To this was added 8 grams of magnesium in the form of shavings and the flask was fitted with a vigurex collum to help keep the liquid in the mixture even close to the boiling point, the top of the vigurex was attached to a hose which lead into some KOH pellets to try to keep water out of the reaction medium though air could still make it in.

The amounts that I use corresponeded to a 25% run of the run in the patent example number 1. The kerosene was clear and upon addition of a small piece of sodium small bubbles appeard on the surface after some time but for the most part it was unreactive. The patent also gives procedures for sodium, however it takes a 15 hour reflux as opposed to the 4 hour reflux for potassium and I just didn't have the time.

Continuing on, the mixture was heated slowly as I was wary of what was described as "a violent eruption of H<sub>2</sub>" the solvent got fairly hot and still no reaction, the magnesium shavings took up a large volume and didn't fit underneath the liquid level. Trying to give the reaction a little start without it going full scale I dissolve ~5 ml isopropyl alcohol in 100 ml kerosene and added 2 drops with no reaction. The mixture continued to heat under magnetic stirring until suddenly some bubbles came to the surface, they looked smokey. The heat was turned to low and the reaction picked up slightly but lacking furhter heating subsided (Note: this was about 1 hour into a gradual heating).

Now that I was fairly sure the reaction wasn't going to run away on me as badly as I feared I turned the heat back up and some time later the reaction started again. At first it looked like the KOH pellets became clear and they formed a film on the bottom of the flask, the stirring bar didn't have the power to dislodge them. Eventually a nice steady reaction was taking place right at the bottom of the flask where the magnesium met the KOH. This continued for some time and it was evident the magnesium was reacting well, white powdery MgO was being produced which was at first somewhat sticky but at the end was free flowing. More of the magnesium passed beneath the surface and more reacted until it was just flakes of magnesium swirling in the reaction medium but the reaction slowed down greatly. During this time 25 drops of the isopropyl alcohol/kerosen mixture was added and the vigor of the reaction increased slightly for some time then slacked off again. This was 4 hours into the reaction and approximately 75% of the magnesium had reacted.

Being that I was running out of daylight I had to shut down the reaction. I left it stirring with the heat off for a few hours (which was much longer then I intended) while it cooled and then stoppered the reaction for the night. When I came back the next day I again turned on the stir bar and noticed that the mixture was now brownish as well as the powder. I'm assuming too much oxygen got into it and made some potassium oxides or maybe due to the basicity of the reaction medium and such the isopropyl alcohol underwent some reaction.

To the reaction mixture was added a small amount more of the kerosene/isopropyl alcohol mixture and it was again heated in hopes of reaction more magnesium and also to liquify any potassium presnt to allow for me to filter it. However after another hour no apparent reaction had taken place and the brown discoloration had become more apparent. I decided to allow it to cool some more and filter it.

A buchner funnel was lined with fiberglass insulation and the hot kerosene was poured through it to heat the funnel. Then the solid was poured in all at once despite my fears that the potassium present would ignite and ignite the kerosene and ignite me. However things went well and the mixture was filtered but no potassium was in the filtrate. So I looked at the solid and it wasn't bursting into flames. Curious I took some more kerosene on the side and added a fair amount of isopropyl alcohol to it and grabbed some of the discolored magnesium shavings off the top and tossed them into the alcohol mix, vigorous fizzing ensued and more was added with the same result, I noticed that the funnel was now making popping/crackling sounds like it was threatening to catch on fire so I tossed it into a 5 gallon bucket of water causing incredible fizzing.

No potassium was recovered. My reasons for failing, the isopropyl alcohol has such a low boiling point and I was running the reaction at the boiling point of kerosene, the patent recomends t-butanol which I did not have, this was part of my problem. Additionally I think I should have run the reaciton at a higher temperature, intially I was too afraid to go all out and boil it for fear of an incredible gas evolution but it never got that bad, I should have ran it at boiling like the patent recomended. Finally I should have never left it open to the atmosphere for so long, I think the brown discoloration was due to oxygen going into the reaction mixture and destroying my elemental potassium. Also filtration was not the best option, in theory the kerosene should have been distilled off and dioxane added which is more dense then the potassium and causes it to rise to the surface, then it is either skimmed off or filtered off, the solid all fell out at once so I think that stopped efficent filtering from happening.

All in all it was an easy reaction using OTC materials (for the most part) and assuming I get a good alcohol I believe I could get a good yield from the reaction, I believe the inital hydrogen evolution is the first stage of the reaction and the alcohol pushes the complete reduction of the magnesium but when I was done I had 2 grams of magnesium left, so the reaction hadn't gone to completion. I would be greatly interested with someone else trying this reaction with sodium hydroxide.

[Also, does anyone have a method or source for t-butyl alcohol?]

[Edited on 10/30/2005 by BromicAcid]




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[*] posted on 6-11-2005 at 04:52


Volatility should not have been much of a problem. The alcohol should quickly turn into alkoxide. Potassium alkoxide contacting magnesium metal, producing potassium metal and magnesium alkoxide, and then magnesium alkoxide reacting with potassium hydroxide to form MgO or Mg(OH)2 and pottassium alkoxide again.

I would be inclined to suggest starting the reaction off first - small amount of magnesium metal, quantity of alcohol, trace of carbon tet to kick it off. This should go without heating and if it doesnt work the rest of the reaction will probably not fly.

Then adding the kerosene dilutant and then the rest of the magnesium followed by the KOH in small amounts (while the reaction works to destroy the water).

I would also be inclined to try barbeque lighter fluid rather than kerosene, this is just a gut feeling though based on my understanding this is often pure hexane.
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[*] posted on 6-11-2005 at 10:01


Finally got around to getting the pictures off my computer (which is somewhat broke now) attached is the reaction sequence, the first picture showing all the reactants in the flask before the heat was applied. The second picture shows nearly 4 hours later, the metal still visible is magnesium, most of it had reacted though. However I had to leave and could not work up my solution and as a result I had to leave it and come back the next day, it was left for a few hours exposed to the atmosphere more then I would have liked because I didn't want to cap boiling kerosene. The final picture is from the next day before re-heating to melt any potassium, note that the color is now brown, potassium peroxides/superoxides, oxidations products of those compounds with the kerosene... etc, definatley something considering the striking color change, and as I noted the magnesium turnings recovered gave an almost violent reaction with isopropyl alcohol dissolved in kerosene.

[Again, although this is somewhat off topic this can be thoretically be applied to sodium as well.]

overtime.jpg - 63kB




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[*] posted on 16-1-2006 at 07:18
Glyme?


What about electrodeposition of alkali metals from glymes? For those of you who don't know what I'm talking about, see this page.

Ionic salts can easily dissolve in glymes, forming complexed cations and free anions. The cations can then be plated out, or in our case electrowinned. This is used industrially for Cu, Cr, and Ni, so I imagine it must be extensible to sodium. There shouldn't be anything to react with the metal once its produced, assuming we safely remove the anion product.

So, would this work? Electrolyze NaCl in glyme, vent the chlorine, collect the solid Na?
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[*] posted on 4-2-2006 at 06:09


Today I attempted the preparation of potassium following the information from the patent posted by BromicAcid. The following was the pathway taken.

30g of finely ground KOH was mixed with 16g of Magnesium powder. To the mixture, 200mL of toluene GPR was added. A reflux setup (with an oil bath) was used to bring the mixture to the boiling point of toluene (i.e. approx. 111 deg C). The increase in temperature was done slowly. At an oil bath temperature of approx. 50 deg C 12mL of absolute ethanol were added to the mixture. On increasing the temp. effervescence was noted, especially above 70 deg C (oil bath temperature). At an oil bath temperature of approx. 90-100 deg C vigorous gaseous evolution occured. Collection of the sample of the gas, using an inverted tube over the mouth of the condensor, and combustion of the gas immediately gave the expected 'pop' indicating Hydrogen.

Reflux of the mixture was continued for a further 3 hours. The mixture was left to cool to 90 deg C (oil bath temp) to check for gaseous evolution. At the 3rd hour gaseous evolution slowed down and I decided to stop there. On examining the contents of the RBF, little KOH was left, some magnesum hydroxide was present at the surface, whereas tiny granules with a metallic lusture were present (which I assume were potassium).

The yield was extremely low, most probably because of the low boiling point of the hydrocarbon used. Next time I will try distilling some diesel so to purify it and run the experiment again. All chemicals were GPR grade. Pic attached shows the product.

PS. I have some other pictures of the gas evolution but I do not know how to use scipics. If anybody is interested and ready to help please U2U me.

[Edited on 4-2-2006 by Esplosivo]

Edit to change picture size-davster



[Edited on 24-12-09 by The_Davster]

Product.JPG - 48kB



[Edited on 2-16-2010 by Polverone]




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[*] posted on 4-2-2006 at 11:04


This thread describes the process of putting pictures into posts.

Mineral oil should be worth trying. It has a very high boiling point (well over 300*C) and remains stable at high temperatures. Just don’t try boiling it, it will decompose.

What exactly drives this reaction forward? Is it the lattice energy of magnesium oxide/hydroxide formed?
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[*] posted on 4-2-2006 at 11:25


Sure. Works with aluminum too, for all alkalines and earths -- though the latter of course need to be vacuum distilled off under high heat. Although, I forget, isn't lithium or cesium not possible doing this?

Tim




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