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Author: Subject: CaCO3 in toluene: a superbase?!
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[*] posted on 26-2-2020 at 22:17
CaCO3 in toluene: a superbase?!

This paper from Kim et al in 2002 suggests that anionic surface sites on solid carbonates are superbasic in toluene (and other aprotic solvents? why toluene?!) and that these can be activated by treatment with acetic acid. CaCO3 is a particularly striking case for its usual inertness, but kiln-dried (300 C) MgCO3 gives the highest yields (67%) of ethyl acetoacetate. In a Claisen condensation!

I don't know what to think of it. What a crazy idea. But Jong-ho Kim has an h-index of 33 and Chonnam National University is not some ramshackle operation.

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[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 4-3-2020 at 16:38

"Carbonates were dehydrated at 390 C for 2h in nitrogen flow and then cooled at 100 C"
MgCO3 gives MgO under these conditions, also CaCO3 can be partly converted to CaO.

"The removal of carbon dioxide from carbonates by acetic
acid produces metal oxides without regular structures. "

The raction is rather complex one (if it works at all).
See FIG.3 in the paper - the reaction does not go below ~80 C.
It looks like EtAc is thermally acylated (mono, di and tri) by metal acetates, at least I think so.
However, it is interesting (if it is true).

Klaszczę w dłonie, by było mnie więcej....
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[*] posted on 4-3-2020 at 19:45

I read this paper and found it to be less than satisfying. I was puzzled by the use of acetic acid to produce CaO. After a bit of rumination and looking at the data, I postulate what happens is that calcium acetate, initially produced by the acetic acid, decomposes on heating to acetone and CaO which is presumably trapped in the calcium carbonate matrix. The authors should have explained this if that is what they think is happening. Taking without thought what they said about acetic acid affording CaO is nonsensical without further information.

Based on a citation search in Google Scholar, there has been no follow up on this paper regarding reproduction or testing of the results. Not surprising. It was cited in an interesting Chemical Reviews article:

"Bases and Basic Materials in Chemical and Environmental Processes. Liquid versus Solid Basicity," Chem. Rev. 2010, 110, 2217–2249.

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