thioacetone
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Registered: 15-12-2022
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refluxing under a mild vacuum
Hello I am performing a decarboxylation of ornithine to produce putrescine, using cyclohexanol (which contains some cyclohexanone and
cyclohex-2-en-1-one as catalysts).
It seems to be proceeding quite slowly at reflux temperature ~155 deg C.
I tried to see if the reaction was happening by connecting a tube to the top of the condenser and the other end in a glass of water to see if there
was bubbling (evolved CO2). There was not. However there did appear to be a bubble that came out of the tube when i dipped it in some soapy water.
The solution has been refluxing overnight, and is now a yellow/orange colour. It has deepened in colour from the 8 hour mark to the 12 hour mark.
This is a promising sign of imine formation.
There are popping 'popcorn' noises coming from the setup (?suggesting CO2 formation)
Would pulling a mild vacuum at the top of the condenser assist in removal of CO2 and speed up the reaction?
[Edited on 25-1-2023 by thioacetone]
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Fery
National Hazard
Posts: 990
Registered: 27-8-2019
Location: Czechoslovakia
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I did decarboxylation of proline into pyrrolidine in acetophenone (b.p. 202 C), you did decarboxylation of ornithine in cyclohexanol (b.p. 162 C).
Applying weak vacuum could reduce b.p. (half of the pressure by about 10 C). Do you follow some procedure or do you just want to try whether it is a
way to go? Did you add cyclohexanone and cyclohex-2-en-1-one and in which amount or do you assume they are present as impurities in cyclohexanol?
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thioacetone
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Posts: 16
Registered: 15-12-2022
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Hi I assume they are present in the cyclohexanol
There is a large component of the cyclohexanol that distills at 155 deg and a large component distilling at >166 deg C
I initially tried using spearmint oil in a purified cyclohexanol solvent (fraction 160-166 deg C). This did not work to decarboxylase ornithine.
However phenylalanine was successfully decarboxylated using spearmint oil in unpurified cyclohexanol.
[Edited on 25-1-2023 by thioacetone]
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