Maja
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Carboxylic acids condensation.
I have searched about it heavily, but couldn't found anything except in "toluene ---> benzaldehyde" thread were formic and benzoic acids were
condensed to produce benzaldehyde. What about longer chain carboxylic acids condensation ? Maybe someone can link me to patent/journal numbers or even
upload them ? For example : How to prepare catalyst ? I'm quite new to this field. Thanks for help.
P.S. I have just found that this type of reaction is called "ketonic decarboxylation" and found some information ! But we can still disscuss.
[Edited on 16-9-2008 by Maja]
[Edited on 16-9-2008 by Maja]
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not_important
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Look for Claisen Condensation - http://www.organic-chemistry.org/namedreactions/claisen-cond... - if I'm understanding what you are asking about. If you are talking about
thermal reaction of the acid to give decarboxylation and a ketone, then
http://tinyurl.com/5g39mq
http://www.vurup.sk/pc/vol47_2005/issue1/pdf/PC_1_2005_Vojtk...
EP0085996 and US6369276
and looking through this http://www.organic-chemistry.org/search/search.cgi?zoom_quer...
may help.
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Nicodem
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Maja, please edit your post properly by describing what are you asking. The tittle talks about "Carboxylic acids condensation" (which in case of their
condensation with aldehydes is indeed called the Claisen condensation, but you don't say what you want to condense them with), but then in the post
you go on talking about some reactions unrelated to carboxylic acid condensations (which would be anything from esterification, Claisen and
Friedel-Crafts, too many to just guess what you mean). Describe explicitly what kind of reaction you talk about and provide some references. Nobody
here can read your mind.
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Maja
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Oh, I can't edit that post now ! Damn! Maybe administrator can rename the topic to "Ketonic Decarboxylation" or something like what ? I'm talking
about this type of reaction where for example acetic acid is transformed to acetone by high temperature and catalyst metals oxides/metals is used:
MnO2 on Al2O3, ZrO2, ZnO, Al/Mg and so on ...
R-CO2H ---temp/catalyst---> R1(CO)R2 + CO2 + H2O
But I'm also interested in ketonic decarboxylation(is it still called ketonic?) where two carboxylic acids is involved :
R-CO2H + R-CO2H --->temp/catalyst---> R-CHO + CO2 + H2O
In this paper :
https://sciencemadness.org/talk/viewthread.php?action=attach...
they use a lot of different catalyst with yields varying 75-90%, also wide pick of catalyst, but they aren't writing about the ways of preparing them
! So my question is: maybe someone replicated that kind of reaction in their garage and would like to share experience about it ? Especially how to
prepare them ?
Excuse me for inaccurate questions !
P.S. Thank you not_important, those were helpful !
[Edited on 17-9-2008 by Maja]
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Nicodem
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What exactly are you asking? Only about how to prepare the catalyst? You just follow the instructions given or follow the reference given or just
search the literature or just assume that unmodified commercial material was used...
There are numerous threads already on this topic with plenty of papers uploaded and I don't exactly know why you opened a new one and did not even
refer to the old ones. Anyway, depending on the substrates, sometimes you can use the Dakin-West reaction which works if one of the acids is an
alpha-amino acid or it has a sufficiently acidic alpha-hydrogen (alpha substituted with groups that stabilize the carboanion). Unfortunately this
condition is rarely meet, but there are a bunch of other methods for preparing ketones and using carboxylic acids as starting material is rarely the
best option.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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