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MeSynth
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I tried to understand the post cylco made. He claims in his second post that using no solvent is the method of choice. He says he mixed a and b then
distilled at 165C and then extracts freebase PPA from reaction flask mixture (byproducts are distilled). He isn't very clear in some areas... The
following is my original revision of his post. If anyone can point out screw ups or point out ways to make it more efficient feel free.
-----------------------------------------------------------
Conversion of benzaldehyde into PPA. (Akabori)
Into a suitable distillation apparatus 1 gram of l-alanine is added for every 2 ml of benzaldehyde to be used.
EXAMPLE I
A stir bar is added to a 500ml round bottom flask then 200ml of benzaldehyde and 100grams of l-alanine are added with stirring. At this point the
round bottom flask is immersed in an oil bath which has been pre heated to 150-160C. It is essential to keep the stir bar spinning and the heat at
150C-159C (benzaldehyde boils in the 170s) for the duration of the reaction. The reaction is considered complete when CO2 evolution stops. [Reaction
time >1.5hrs]
When reaction has stopped and the mixture has cooled enough to handle (it should still be hot) extract with toluene. All toluene extracts are combined
and set aside to cool. Filter off any precipitates that form as a result of cooling.
Extract the combined toluene extracts with dilute HCl to remove the amines.
Wash the aqueous amine solution with DCM taking care not to create an emulsion.
Basify the aqueous amine solution by slowly adding granules of NaOH with stirring.
-method I
Now extract the freebase with diethyl ether. The ether extract is placed into a distillation apparatus. The ether and the free base are distilled
under reduced pressure. Wash out the condenser and adapters with ether. The freshly distilled freebase/ether mixture is dried with sodium sulfate.
After the sodium sulfate is filtered off and washed with additional dry ether the mixture is ready for dry hydrogen chloride gas. The beaker
containing the freebase/ether is placed into an ice bath and chilled to allow for better absorption of the hydrogen chloride. After it has cooled
considerably dry anhydrous hydrogen chloride gas is bubbled into the mixture until no more precipitate forms. The precipitate is then filtered off. If
unsure about the completeness of the extraction repeat drying and addition of hydrogen chloride.
-method II (original method)
The ether is distilled out of the freebase (the freebase shouldn't go with it but if it does skip some steps). The distilled ether is then dried with
sodium sulfate and filtered. To the freebase is added a few ml of the dry ether to take up the freebase. The freebase/ether is poured into a smaller
flask for a more efficient distillation. Carefully extract the larger flask until no freebase remains. Carfully distill off the ether once again and
then switch receiving flasks. Distil the freebase. Wash the inside of the apparatus with dry ether and combine with the distilled freebase. Add enough
ether to the free base to allow for gassing with HC (about 3 times the volume of the freebase). Then dry the freebase/ether extract with anhydrous
sodium sulfate and filter. Wash the sodium sulfate and the filter with some dry ether. Gas the now dry freebase/ether mixture with anhydrous hydrogen
chloride and filter off the precipitate.
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MeSynth
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What would happen if you used cinnamaldehyde in place of benzaldehyde? What would the product be?
For example..
200gm cinnamaldehyde and 100gm l-alanine
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questions
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I tried this reaction about 1 month ago, I mixed one teaspoon of l-alanine with 250ml of cinnamon aldehyde and heated it to 150C. After 5 min the
whole garage stunk intensly of cinnamon and the solution turned dark red. I dont know what the product was but I'm assuming their was a reaction of
some sort as their was lots of fizzing
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questions
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I'm always wondering if the cinnamon will react with the n-methylalanine because the benzaldehyde i make has cinnamon still in it about 20% cinnamon
actually. So when I mix the solution with n-methylalanine I'm hoping it wont stop the benzaldehyde reacting with the n-methylalanine
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overload
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Can the freebase produced via the akabori be distilled without a vacuum? In other words will the free base decompose and will there be losses?
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overload
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I don't know what to make of this. I just read that the bp of ppa free base is 108C? If the main reaction is taking place at 150C how does the free
base stay in the reaction flask? Is it forming an Azeotrope with the Benzaldehyde? If so I would have to guess that using less L-Analine would
increase yields in the reaction flask since the more benzaldehyde that is taken up in the reaction more and more free base will escape into the
distillate. Could this be why there is such a low yield? Also why doesnt cycloknite extract with the reaction mixture with Diethyl Ether instead of
toluene since this would make int easier to try to recycle the benzaldehyde (it there is any to recycle and even if you did recycle it I wouldnt use
it for anything but running it through this reaction again). If this is the case maybe there is a way to take the distillate and extract the free base
with benzaldehyde and distil out the by-products at 150C again then convert the benzaldehyde to the bisulfite adduct and then basify and extract the
ppa with ether. I have no experience or time and money to test out this theory right now. Anyone have any clue if what I'm saying has any truth? If I
ran it the way cycloknite did in his second post I would use less L-Analine but for the sake of science I would first try to replicate his results
before implementing my own theories.
[Edited on 10-10-2011 by overload]
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Nicodem
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overload, questions and MeSynth: Please do not persistently crap in this thread! This is not a garbage bin.
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overload
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Quote: Originally posted by Nicodem  | | overload, questions and MeSynth: Please do not persistently crap in this thread! This is not a garbage bin. |
Well these are serious questions I have and you guys are my only source of answers. I could go to a college and ask the chemistry teachers but were is
that going to get me.. I may not be adding anything to the thread right now but I may in the future add some great stuff so help me out and see what
happens. 
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overload
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Has anyone read this patent? It has some of the same concepts in it that I talked about earlier with the benzaldehyde azerotrope with the free base.
US4552957
I've only had the chance to read the summary but it sounds really interesting.
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watson.fawkes
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Are they serious
scientific questions or serious production help questions? Scientific questions are phrased with care, not written hastily, pay attention to notation
and capitalization, avoid slang acronyms, and put effort into being understood by potential collaborators. I does not seem to me that you are treating
your questions with any great degree of scientific effort.
More pointedly, it doesn't matter to most anybody on this forum that you see it as a unique oracle in your life. The participants here are ordinary
amateurs, not a paid help desk, and if you want the respect of their attention it behooves you to pay proper respect in how you ask your questions.
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fanglongcan
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| Quote: Originally posted by MeSynth | I tried to understand the post cylco made. He claims in his second post that using no solvent is the method of choice. He says he mixed a and b then
distilled at 165C and then extracts freebase PPA from reaction flask mixture (byproducts are distilled). He isn't very clear in some areas... The
following is my original revision of his post. If anyone can point out screw ups or point out ways to make it more efficient feel free.
-----------------------------------------------------------
Conversion of benzaldehyde into PPA. (Akabori)
Into a suitable distillation apparatus 1 gram of l-alanine is added for every 2 ml of benzaldehyde to be used.
EXAMPLE I
A stir bar is added to a 500ml round bottom flask then 200ml of benzaldehyde and 100grams of l-alanine are added with stirring. At this point the
round bottom flask is immersed in an oil bath which has been pre heated to 150-160C. It is essential to keep the stir bar spinning and the heat at
150C-159C (benzaldehyde boils in the 170s) for the duration of the reaction. The reaction is considered complete when CO2 evolution stops. [Reaction
time >1.5hrs]
When reaction has stopped and the mixture has cooled enough to handle (it should still be hot) extract with toluene. All toluene extracts are combined
and set aside to cool. Filter off any precipitates that form as a result of cooling.
Extract the combined toluene extracts with dilute HCl to remove the amines.
Wash the aqueous amine solution with DCM taking care not to create an emulsion.
Basify the aqueous amine solution by slowly adding granules of NaOH with stirring.
-method I
Now extract the freebase with diethyl ether. The ether extract is placed into a distillation apparatus. The ether and the free base are distilled
under reduced pressure. Wash out the condenser and adapters with ether. The freshly distilled freebase/ether mixture is dried with sodium sulfate.
After the sodium sulfate is filtered off and washed with additional dry ether the mixture is ready for dry hydrogen chloride gas. The beaker
containing the freebase/ether is placed into an ice bath and chilled to allow for better absorption of the hydrogen chloride. After it has cooled
considerably dry anhydrous hydrogen chloride gas is bubbled into the mixture until no more precipitate forms. The precipitate is then filtered off. If
unsure about the completeness of the extraction repeat drying and addition of hydrogen chloride.
-method II (original method)
The ether is distilled out of the freebase (the freebase shouldn't go with it but if it does skip some steps). The distilled ether is then dried with
sodium sulfate and filtered. To the freebase is added a few ml of the dry ether to take up the freebase. The freebase/ether is poured into a smaller
flask for a more efficient distillation. Carefully extract the larger flask until no freebase remains. Carfully distill off the ether once again and
then switch receiving flasks. Distil the freebase. Wash the inside of the apparatus with dry ether and combine with the distilled freebase. Add enough
ether to the free base to allow for gassing with HC (about 3 times the volume of the freebase). Then dry the freebase/ether extract with anhydrous
sodium sulfate and filter. Wash the sodium sulfate and the filter with some dry ether. Gas the now dry freebase/ether mixture with anhydrous hydrogen
chloride and filter off the precipitate.
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The ether and the free base are distilled under reduced pressure.
Distillation temperature?
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ScienceSquirrel
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Thread Pruned
23-2-2012 at 03:52 |
cal
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Bandwith
| Quote: Originally posted by Ramiel | | I hate to be off topic CycloKnight (it looks like there's a good chemist here), but that's 37 pictures there... omg bandwidth! Someone pays for that
megabyte or so for each person who view this page. In this case, perhaps a picture is worth omitting for a few concise descriptions, eh?
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If you don't have unlimited then your not with the 20 th century
program.
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tadpoleannihilater
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Appologies for bringing up an old thread but I would like to know the following.
What ph should the HCL have when using it to extract the amines from the toluene?
After reading through a few of these threads I have decided to consider the ph of the HCL as important as it may damage the amines if to strong.
Im also having a bit of trouble trying to raise the ph of the hcl. I would basically only need 5ml in 1000ml to get a slightly acidic solution. Does
this seem right to you guys?
My hcl is muriatic acid passed through activated carbon a few times to remove some of the yellow goo.
So right now I guess I could run a test to see if this small amount of hcl would be sufficient.
[Edited on 10-10-2013 by tadpoleannihilater]
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WChase501
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During theAkabori reaction wasn't a primary amine used to catalyze the main reaction?....
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