PainKilla
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Acetone Experiments
In conjuction with the DPPP thread here is some interesting resutls I have attained:
Acetone + HCl---> Yellow mixture-->(time)-->dark red mixture
Acetone + H2SO4--> Yellow mixture-->(time)-->dark red mixture
Acetone + NaOH--> Yellow mixture
I find this quite intersting. What happens to the acetone under all these situations. it would be of use because mesitylene and all the various
prodcuts formed could be useful to the average mad scientist  .
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Synopsis
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You are condensing acetone via aldol reactions. At first the enol of acetone is formed (a step catalyzed by both bases and acids) and this enol reacts
with acetone to form 4-hydroxy-4-methyl-pentan-2-one (a formal dimer of acetone).
Acids catalyzes the dehydration of this dimer which results in the formation of 4-methyl-pent-3-en-2-one. The latter probably is the cause of that
yellow color you get.
It turns red with time because other aldol reactions will take place (which ultimately produces mesitylene) as well as michael additions in acidic
conditions (which ultimately produces red tar...).
[Edited on 30-1-2005 by Synopsis]
Your theory is crazy, but it\'s not crazy enough to be true. - Niels Bohr
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PainKilla
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Intersting, do you have any direct references to this? I say it only because it is of much interest to the DPPP people now. Also, mesitylene is sueful
for make benzene and deratives so yea.
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Synopsis
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I found two papers in the older litterature treating this subject :
Hofmann, A. J. Am. Chem. Soc. 1909, 31, 722
Gardner, H. A.; Knauss, C. A. Ind. Eng. Chem. 1928, 20, 599
The first one treats the condensation of acetone over CaO; the major product being 4-methyl-pent-3-en-2-one (referred to as "mesityl
oxide" along with small amounts of isophorone and mesitylene. The second paper
is an industrial process for the condensation of acetone over acidic resins, also yielding 4-methyl-pent-3-en-2-one.
I remember seeing somewhere an article about the condensation of methyl ketones to 1,3,5-trisubstituted benzenes (meaning mesitylene from acetone).
I'll try to dig it back during the week.
Your theory is crazy, but it\'s not crazy enough to be true. - Niels Bohr
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PainKilla
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Ah, thank you very much, those are very intersting especially the first one. I need to get some lime and try that....
Do you know what happens when the prodcuts of that get exposed to the same condtions.... aka mesityl oxide exposed to acidic resin or basic media :p.
[Edited on 30-1-2005 by PainKilla]
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woelen
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| Quote: | Originally posted by Synopsis
It turns red with time because other aldol reactions will take place (which ultimately produces mesitylene) as well as michael additions in acidic
conditions (which ultimately produces red tar...). |
Thanks, now I finally have an explanation for an observation, I have done quite some time ago.
I once had some acetone added to H2SO4 (98%), both of high purity. The liquids were mixed and at that time quite some heat was produced. I left the
mix for a while, in a tightly stoppered flask. Over time it became orange, then red. Finally, the liquid was very viscous and syrupy. I really was
amazed by that, but noone could explain it to me, not did Google help me on that. Now I have a suitable explanation.
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