Is there a potential reaction that would occur between ethanol and aluminum? If so, would it potentially create anything toxic?
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1$\begingroup$ Yes it is, it is an industrial way to prepare aluminiuum isopropoxide. $\endgroup$– permeakraCommented Feb 4, 2016 at 8:32
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3$\begingroup$ In what situation? Normally there's no significant reaction. $\endgroup$– MithoronCommented Feb 4, 2016 at 16:16
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$\begingroup$ Mercury(II) chloride is a necessary condition for this synthesis to occur, because usual aluminum is covered by a thin waterproof and continuous protective layer of aluminum oxide (alumina). This layer prevents the metal aluminum to get in touch with any liquid. In the presence of dissolved mercury chloride, the layer is not continuous anymore. So aluminum can react with water, ethanol, or isopropanol, producing gaseous hydrogen and aluminum hydroxide (or ethoxide, or isopropoxide). $\endgroup$– MauriceCommented Jun 21, 2022 at 21:09
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$\begingroup$ @Maurice, For rapid synthesis, a way of breaking the Al2O3 coating is needed (might Ga would work, too?), but for long-term storage, aluminum is attacked by the lower alcohols, as I've observed by using a container with (unanodized) Al top for storing isopropanol. After a year or so, the top was covered with a white crust and badly corroded. No Hg was involved in this inadvertent test! $\endgroup$– DrMoishe PippikCommented Jun 24, 2022 at 15:23
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$\begingroup$ Thank you for the information, Dr Pippik. I did not know about this extremely slow reaction. And of course, gallium works as well. $\endgroup$– MauriceCommented Jun 24, 2022 at 16:12
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1 Answer
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The reaction of aluminum and ethanol forms aluminum triethoxide, $\ce{ Al(OC2H5)3}$, but the reaction is fairly slow at room temperature, particularly if the aluminum is anodized. In the presence of any moisture it decomposes into aluminum hydroxide and ethanol.
The Safety Data Sheet indicates that aluminum triethoxide is both flammable and can cause "severe skin burns and eye damage", but in atmospheric conditions it likely decomposes as quickly as it forms, so the main adverse effect will be the corrosion of the aluminum, covering it with a white crust of $\ce{Al2O3}$ (I've seen this happen to an aluminum lid on a container used for ethanol).
UNH has posted a chart that shows that anodized aluminum is resistant to ethanol attack, but does not state at what temperature, so you may have to experiment to see if it suitable in your application.
BTW, many other alcohols react in a similar manner, such as isopropanol, which forms aluminium isopropoxide with aluminum.
answered Feb 4, 2016 at 21:43
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$\begingroup$ I have seen the same: the main adverse effect will be the corrosion of the aluminum, covering it with a white crust of Al2O3 A l 2 O 3 (I've seen this happen to an aluminum lid on a container used for ethanol). $\endgroup$– iepCommented Nov 10, 2022 at 21:34