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Author: Subject: Preparation of aluminium triethoxide without mercury?
fleroj
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[*] posted on 1-8-2017 at 07:33
Preparation of aluminium triethoxide without mercury?


Wikipedia lists amalgam + ethanol or iodine and mercury chloride as catalysts.

I suppose the former would work with gallium as well, but that's rather cost-prohibitive.

Since the second route works with just iodine for magnesium ethoxide,could it be possible for Al as well?
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karlos³
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[*] posted on 1-8-2017 at 11:19


It works, see here: https://www.researchgate.net/publication/279653949_Catalytic...
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[*] posted on 1-8-2017 at 12:19


It works but is extremely slow with aluminium foil pieces. I used 3g of iodine for 30g of aluminium or so. I even did a video on my crappy youtube channel about aluminiumisopropoxide.



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karlos³
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[*] posted on 1-8-2017 at 12:37


What about activating the Al similar to the others ways to activate Mg metal in a grignard? I.e. a quick wash with a diluted acidic solution, followed by solvents?
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[*] posted on 2-8-2017 at 03:17


Treating the aluminium with gallinstan should work and most likely make the iodine not necessary.
Ask melgar

[Edited on 2-8-2017 by notoxicshit]
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[*] posted on 2-8-2017 at 04:39


Ooh, this is my specialty.

First off, what karlos posted is somewhat wrong. There's a significant side-reaction whereby iodoethane is produced, which uses up the iodine. So you can't just use iodine as a catalyst in minute quantities, like you can with a Grignard. Also, Al2O3 is much better at protecting aluminum metal than MgO is at protecting magnesium, and forms much more quickly and is less reactive. Consider how difficult it is to burn aluminum in air compared to magnesium, for example.

This reaction works with galinstan, and even with just gallium at low concentrations if you use hot alcohol. (50˚C - 60˚C or so) Rather than galinstan though, I'd actually recommend using gallium/indium eutectic alloy, which is a 3:1 mixture of gallium and indium by mass. It has a melting point of 15˚C (gallium is 30˚C) and when alloyed with aluminum, this means that the alloy contains only group 13 elements, which removes any complicating factors that tin impurities might have on the results.

The gallium and indium can be recycled, since they don't react with ethanol, but there will be a lot of impurities from the aluminum left behind. You should be able to separate them from the sludge by treating the sludge with NaOH to remove most of the aluminum, (gallium will react with NaOH solutions, but only extremely slowly) then treat with dilute HCl briefly to remove metal oxides, then hot, stronger HCl with peroxide and/or a very small amount of HNO3 to get the gallium and indium. After this, I've had good luck boiling off any excess acid (which also destroys any residual peroxide) diluting with water, then adding aluminum in small chunks in a warm solution to reduce the indium and gallium back to metals.

One thing about this reaction is that you tend to need aluminum that's at least 99% or so, with minimal surface area. The only form of aluminum that comes this way is aluminum electrical wire, which is 98.5% aluminum in its most frequently-encountered alloy. I prefer 3040 Al, since the main impurity is magnesium, and that's rarely a problem for my purposes. I usually melt it down before using it and alloy it while it's molten, but if you're starting with anything that's not foil, try this:

Get a few drops of galinstan or gallium/indium eutectic alloy. This can be obtained by breaking open a Geratherm mercury-free thermometer, which can be purchased from Walmart in the US for about $5. Then get the liquid alloy to wet the aluminum by scratching at the aluminum through the liquid alloy. There will be an obvious reaction when they start to mix. When this happens, add alcohol to it, which will then start to react with the aluminum where it joins the galinstan.

You'll be left with a saturated solution of Al(EtO)3 in EtOH, with sludge and residual metal at the bottom. You can heat it up to increase the solubility of your desired product, and increase the reaction rate.

Edit: I can sell gallium and indium for $0.50 US / gram, but probably only domestic, and you'd have to pay shipping of $2-$3.

[Edited on 8/2/17 by Melgar]




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[*] posted on 2-8-2017 at 05:57


at least with isopropanol and commercial aluminum foil + small amount of iodine I was able to make al-propoxide. Therefore karlos is not wrong. However this reaction takes ages.



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[*] posted on 2-8-2017 at 09:20


Melgar didn´t say I was completely wrong, just somewhat ;D
That´s ok, his explanation was really plausible as to why my uninformed guess didn´t fit here in this case, also I learned something new! ;)
As for Al-isopropoxide preparation vs. Al-ethoxide, is steric hindrance the reason why iodine works for the one but results in a competing side reaction for the other?
I see I2 usually employed for the isopropoxide, thats why I suggested it for the ethanolate too.
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[*] posted on 2-8-2017 at 12:03


yeah melgars approach definitely seems better ad faster because of the larger surface area. if i do this again once ill use alcl3.



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[*] posted on 2-8-2017 at 21:57


Group-13-based low-mp alloys seem like such little work to me that I'm surprised people would consider anything else. Of course, that's because I have more gallium and indium than I know what to do with, which isn't the case for most people. They're plenty useful for other things too though; I use drops of the stuff all the time to lower the melting point of solder when I want to take sensitive components out of a circuit board without damaging them.

Oh, the other reason I was saying what karlos had needed more explanation: iodoethane can react with aluminum too, producing AlIEtEtO or something like that, which is this bastard child of a Grignard and what you actually want, and so you can't really claim that what you have is what you think it is. It might react mostly the same, but that iodine might come off too, and catalyze some undesirable side product. Virtually all of that is true of aluminum isopropoxide too, though it's anyone's guess which one is more of a problem. I'm not sure where it's assumed all that iodine is going though. Another problem is that the reaction producing the alkyl halide also produces water (HI + EtOH = EtI + H2O) and thus Al2O3, which is why it's such a slow reaction.

I've also figured out how to get aluminum to react like it does in Al/Hg reactions, but using gallium and indium salts. You need to add the gallium first though, and it has to be at an elevated temperature such that the gallium is liquid when it's reduced.




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[*] posted on 2-8-2017 at 22:05


Quote: Originally posted by karlos³  
It works, see here: https://www.researchgate.net/publication/279653949_Catalytic...


This refuses to open for me. Any chance of a DOI instead please..........?


/CJ




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[*] posted on 4-11-2018 at 06:56



I am investigating the use of activated carbon (AC) as a catalyst in place of mercury. As an example of the application of AC, see for example, 'Activated carbon for aerobic oxidation: Benign approach toward 2-benzoylbenzimidazoles and 2-benzoylbenzoxazoles synthesis' by Kai Bao, et al, at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4603700/ .

My speculated path, first, we have electrostatic interactions (for example, Coulombic interactions) between ionic salts (like Aluminum producing positively charged Al3+) and ‘charged activated carbon pore surfaces’ (see https://www.sciencedirect.com/topics/materials-science/carbo... ). I would describe the latter below on the surface of activated carbon (note, AC is a known photocatalyst so UV or solar light in the presence of moisture and oxygen, see https://www.sciencedirect.com/science/article/pii/S092633731... , or oxidizing agents or heating may induce radical creation):

AC = AC+ + e-

And, in the illustrative theoretical presence of H2O2, for example, to understand the underlying chemistry (NOT to be added to alcohol), a possible one electron reduction chain:

H2O2 ⇌ H+ + HO2-
e- + H+ ⇌ .H
.H + HO2- = OH- + .OH

Net: H2O2 + e- = OH- + .OH

Or, as AC = AC+ + e- , we equivalently have:

H2O2 + AC = AC+ + OH- + .OH

This precise relation was originally proposed by Kurniawan et al., 2009 and Bach et al., 2011 and appears in this thesis https://tspace.library.utoronto.ca/bitstream/1807/68525/1/Si... , to quote:

“GAC has been known to act as a catalyst in the decomposition of H2O2 (Khalil et al., 2001) and has been used in a number of drinking water treatment plants due to its ability to quench H2O2 (Cotton et al.., 2010). Two major theories have been put forward for quenching mechanism of hydrogen peroxide by GAC (Kurniawan et al., 2009 and Bach et al., 2011). The hypothesis by Kurniawan et al. (2009) is given as follows:
AC + H2O2 → AC+ + OH− + .OH Equation 1. 11
AC+ → AC + H+ + .OOH Equation 1. 2 ”

Other theoretically related works include https://www.researchgate.net/publication/276120744_Enhanced_... to quote:

“... literature has reported that carbon materials have reducing power. Activated carbon is known to serve as a redox mediator, possibly by reactions involving carbonyl/quinone groups on the surface, and a portion of these functional groups have very low redox potentials…”

Also, https://www.nap.edu/read/12646/chapter/6?term=%22samples+of+... , which notes that ‘samples of new unused carbon added to water give a pH reading around 10’ .

All of the foregoing implies to me a possible role for activated carbon (AC) in an aluminum, ROH and some water (I may try adding a small amount of MgCl2 as an electrolyte given the galvanic corrosion of aluminum in the presence of noble carbon in seawater, see https://www.corrosionpedia.com/galvanic-corrosion-of-metals-... ) mix in the following proposed reaction scheme:

3 x [ AC = AC+ + e- ]
3 x [ H2O ⇌ H+ + OH- ]
3 x [ H+ + e- = .H ]
Al --> Al3+ + 3 e-
Al + 3 OH- -->Al(OH)3 + 3 e-
3 x [ AC+ + e- = AC ]
3 x [ .H + ROH = .RO + H2 (g) ]
3 x [ .RO + e- = RO- ]

Net:
2 Al + 3 ROH + 3 H2O --AC--> Al(RO)3 + Al(OH)3 + 3 H2 (g)

As a side comment that may impact reactivity, note that hydrogen is chemisorbed on carbon surfaces (see https://www.sciencedirect.com/topics/materials-science/carbo...) and in the presence of UV or solar light, a likely beneficial added presence of the hydrogen atom radical (.H).

To prepare a form of activated carbon, I am thinking of working with very fine carbon or perhaps graphite, soak it in a select alcohol of interest, ignite the mix to heat the carbon and imbue it with organic groups, quench the fire and let it aerate. Repeat the soaking in alcohol, ignition, quenching and aeration. The idea is to introduce oxygen containing groups which are known to impact the polarity on carbon surface (see https://www.nap.edu/read/12646/chapter/6#34 ).

[Edited on 5-11-2018 by AJKOER]
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[*] posted on 5-11-2018 at 15:41


Hmmm, maybe use sodium ethoxide as a catalyst?
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[*] posted on 5-11-2018 at 16:08


Quote: Originally posted by AJKOER  

I am investigating the use of activated carbon (AC) as a catalyst in place of mercury. As an example of the application of AC, see for example, 'Activated carbon for aerobic oxidation: Benign approach toward 2-benzoylbenzimidazoles and 2-benzoylbenzoxazoles synthesis' by Kai Bao, et al, at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4603700/ .

My speculated path, first, we have electrostatic interactions (for example, Coulombic interactions) between ionic salts (like Aluminum producing positively charged Al3+) and ‘charged activated carbon pore surfaces’ (see https://www.sciencedirect.com/topics/materials-science/carbo... ). I would describe the latter below on the surface of activated carbon (note, AC is a known photocatalyst so UV or solar light in the presence of moisture and oxygen, see https://www.sciencedirect.com/science/article/pii/S092633731... , or oxidizing agents or heating may induce radical creation):

AC = AC+ + e-

And, in the illustrative theoretical presence of H2O2, for example, to understand the underlying chemistry (NOT to be added to alcohol), a possible one electron reduction chain:

H2O2 ⇌ H+ + HO2-
e- + H+ ⇌ .H
.H + HO2- = OH- + .OH

Net: H2O2 + e- = OH- + .OH

Or, as AC = AC+ + e- , we equivalently have:

H2O2 + AC = AC+ + OH- + .OH

This precise relation was originally proposed by Kurniawan et al., 2009 and Bach et al., 2011 and appears in this thesis https://tspace.library.utoronto.ca/bitstream/1807/68525/1/Si... , to quote:

“GAC has been known to act as a catalyst in the decomposition of H2O2 (Khalil et al., 2001) and has been used in a number of drinking water treatment plants due to its ability to quench H2O2 (Cotton et al.., 2010). Two major theories have been put forward for quenching mechanism of hydrogen peroxide by GAC (Kurniawan et al., 2009 and Bach et al., 2011). The hypothesis by Kurniawan et al. (2009) is given as follows:
AC + H2O2 → AC+ + OH− + .OH Equation 1. 11
AC+ → AC + H+ + .OOH Equation 1. 2 ”

Other theoretically related works include https://www.researchgate.net/publication/276120744_Enhanced_... to quote:

“... literature has reported that carbon materials have reducing power. Activated carbon is known to serve as a redox mediator, possibly by reactions involving carbonyl/quinone groups on the surface, and a portion of these functional groups have very low redox potentials…”

Also, https://www.nap.edu/read/12646/chapter/6?term=%22samples+of+... , which notes that ‘samples of new unused carbon added to water give a pH reading around 10’ .

All of the foregoing implies to me a possible role for activated carbon (AC) in an aluminum, ROH and some water (I may try adding a small amount of MgCl2 as an electrolyte given the galvanic corrosion of aluminum in the presence of noble carbon in seawater, see https://www.corrosionpedia.com/galvanic-corrosion-of-metals-... ) mix in the following proposed reaction scheme:

3 x [ AC = AC+ + e- ]
3 x [ H2O ⇌ H+ + OH- ]
3 x [ H+ + e- = .H ]
Al --> Al3+ + 3 e-
Al + 3 OH- -->Al(OH)3 + 3 e-
3 x [ AC+ + e- = AC ]
3 x [ .H + ROH = .RO + H2 (g) ]
3 x [ .RO + e- = RO- ]

Net:
2 Al + 3 ROH + 3 H2O --AC--> Al(RO)3 + Al(OH)3 + 3 H2 (g)

As a side comment that may impact reactivity, note that hydrogen is chemisorbed on carbon surfaces (see https://www.sciencedirect.com/topics/materials-science/carbo...) and in the presence of UV or solar light, a likely beneficial added presence of the hydrogen atom radical (.H).

To prepare a form of activated carbon, I am thinking of working with very fine carbon or perhaps graphite, soak it in a select alcohol of interest, ignite the mix to heat the carbon and imbue it with organic groups, quench the fire and let it aerate. Repeat the soaking in alcohol, ignition, quenching and aeration. The idea is to introduce oxygen containing groups which are known to impact the polarity on carbon surface (see https://www.nap.edu/read/12646/chapter/6#34 ).

[Edited on 5-11-2018 by AJKOER]


You're so amazingly proficient at generating this inane garbage in lots of otherwise coherent threads.
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[*] posted on 6-11-2018 at 14:17


Quote: Originally posted by UC235  
You're so amazingly proficient at generating this inane garbage in lots of otherwise coherent threads.


I was starting to think I was the only one here who thought that of AJKOER. At least this suggestion would have been easily testable (toss in some charcoal and see if it starts the reaction), in stark contrast to his usual "I know this reaction goes, but I'm saying it's a convoluted free radical redox reaction!"




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[*] posted on 8-11-2018 at 09:38


A few points.

> My comment was only that "I am investigating the use of activated carbon (AC) as a catalyst". More recently, in particular, I am looking at carbon black produced by the simple burning of candles or turpentine. Note, "toss in some charcoal " is not exactly what I am suggesting.

> Those who followed my links and further research on Activated Carbon, a photocatalyst, are aware that correctly prepared activated carbon may result in the liberation of electrons and electron holes (especially in the presence of UV/solar light). That both of the latter, if created, can induce radical formation is pretty much accepted science. I will further note if one is using stable TiO2 as a catalyst in an application, there is much science (see, https://www.google.com/search?source=hp&ei=NXTkW7ftLIjl5... , most not in the class of 'inane garbage') further suggesting benefits of combining TiO2 with activated carbon.

> Anyone who thinks that the reaction mix I suggested will not create products is likely seriously wrong. The real question is exactly which products and to what extent, and speculated paths (not really important) if indeed any products of interest are created. Hence the need for experimenting.

> A real criticism of my suggested path is that I should have stressed the starting amount of H2O in the mix should be small (as it feeds the decomposition of the product of interest), and based on H2 production, more water could be added to the system.

In the current thread, there could be enormous benefits in employing carbon, in lieu of mercury, with respect to safety, availability and cost, which may justify checking 'I tried it' box.

[Edited on 8-11-2018 by AJKOER]
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[*] posted on 8-11-2018 at 11:14


Quote: Originally posted by AJKOER  

In the current thread, there could be enormous benefits in employing carbon, in lieu of mercury, with respect to safety, availability and cost, which may justify checking 'I tried it' box.


Quite true, so by all means, try it.




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