Catslovechemistytoo
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Acrylic acid by dehydration of Lactic acid?
Hello everyone. Let's say my goal is to make acrylic acid. One possible route is to oxidize acrolein by Pinnic oxidation. However this is hard because
acrolein is hard to work with. As I did my research, I found a simpler procedure: lactic acid can be dehydrated using fixed bed reactor and various
catalysts. Here for example they are using BaSO4 at 350°C in a quartz tube, using HPLC pump to feed the reactor a solution of lactic acid.
What I don't understand is how to build a fixed bed reactor? How does this apparatus work at all? From my understanding, it's a quartz tube with
catalyst packed inside, which is heated to desired temperature and a preheated solution of lactic acid is sprayed onto it. The products are pumped
away by nitrogen flow and condensed. But they also write that the reactants and products were pre-heated to 160°C to avoid condensation by-products.
How can that be if the b.p. of lactic acid solution is much lower?
What can be used in place of HPLC pump? Can a metal body for the column be used instead of quartz? Or maybe borosilicate glass because 350°C is not
that much for it.
Can the lactic acid solution just be boiled to the catalyst-filled tube instead?
And then, how to separate the reaction products?
I would appreciate any help with this.
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walruslover69
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From my brief reading this doesn't seem to be reasonably feasible on the small scale. This paper outlines that they carried out the reaction in super
and sub critical water. Their ideal yield was accomplished at 40MPa (5800 PSI). Personally I don't know the first place to start when trying to select
a container for 300C 5800PSI water. It seems like there is some really cool aqueous chemistry at these temperature though.
https://www.sciencedirect.com/science/article/abs/pii/S08968...
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Jenks
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This patent using catalytic phosphates uses a much lower pressure flow reactor.
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jackchem2001
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I don't have much to contribute but from the structure of lactic acid I think a carbon monoxide detector should be used for this experiment.
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sykronizer
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Yeah This is NOT something that is weekend project. Trust me you are best forgetting this approach ENTIRELY and trying to source some form of acrylate
from a some consumer product, for example Ethyl methacrylate ester is commonly sold as part of the kits that women use to paint or build up their
crazy fingernails with. Work with what you can get, it takes a nit of lateral thinking, but it can be done.
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Catslovechemistytoo
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What if we just boil lactic acid solution (20-25% like they suggest) through a stainless steel tubing heated by nichrome heating element to 350°C,
packed with catalyst prepared in a way they wrote? Then condense it straight into another flask and distill it right away to avoid side reactions.
Wrap everything in foil to avoid light exposure and add some sort of antioxidant like hydroquinone. With an effective rectification column it should
be possible to separate Acrylic acid.
Does this have any chance to work?
Quote: Originally posted by sykronizer  | | Ethyl methacrylate ester is commonly sold as part of the kits that women use to paint or build up their crazy fingernails with. Work with what you can
get, it takes a nit of lateral thinking, but it can be done. |
Yeah, I was asking about ACRYLATE, not methacrylate. Methacrylates can be easily distilled from polyacrylate plastic.
[Edited on 9-8-2024 by Catslovechemistytoo]
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bnull
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What do you need acrylic acid for?
Quod scripsi, scripsi.
B. N. Ull
P.S.: Did you know that we have a Library?
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