swami.me
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Methylammonium Acetate - Synthesis of Crystal
Hi all,
I am new to organic synthesis. I would like to synthesize Methylammonium Acetate by reacting acetic acid and methyl amine solution (40% in
water) at 0C and grow crystals of it if possible. But I wasn't sure how to get dry crystals.
Please help me.
Swami
[Edited on 22-1-2016 by swami.me]
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chemrox
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you could conceivably do this by heating the solution to release MeNH2 running it through a drierite/molecular sieve column hence through GAA. Have
you checked the water solubility? You might get away with mixing the two ingredients MeNH2 and GAA but you will have too look up the product to see
what its solubility is.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Praxichys
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There is quite a bit of info in this thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=8182
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swami.me
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Quote: Originally posted by chemrox  | | you could conceivably do this by heating the solution to release MeNH2 running it through a drierite/molecular sieve column hence through GAA. Have
you checked the water solubility? You might get away with mixing the two ingredients MeNH2 and GAA but you will have too look up the product to see
what its solubility is. |
The material is highly soluble in water. I don't have the numbers in hand.
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swami.me
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I read it but couldn't really tell what the best solution was. I am little weak in chemistry as I am a electrical engineering major.
I plan to take the methylamine solution and put NaOH in it to release CH3NH2. This gas will go through a NaOH/KOH column to remove any moisture and
then pass it over acetic acid. Do I need to heat up the acetic acid? Also will cooling this reaction in fridge yield Methylammonium acetate crystals?
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Nicodem
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Thread Moved
22-1-2016 at 08:27 |
Nicodem
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| Quote: Originally posted by swami.me | | I am new to organic synthesis. I would like to synthesize Methylammonium Acetate crystals by reacting acetic acid and methyl amine solution (40% in
water) at 0C. But I wasn't sure how to get dry crystals. |
It is not called to synthesize crystals, but to grow crystals. This is done by numerous techniques. The most common are the crystallization from a hot
solution by slow cooling and the slow evaporation techniques. For some compounds it is best to use seeds. As for how difficult it is, it depends on
how large crystals you want to grow. You can try letting a solution of methylammonium acetate in ethanol or 2-propanol evaporate from an open beaker
in a dry place (I think methylammonium acetate is hygroscopic). It might give you mm size crystals.
…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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swami.me
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| Quote: Originally posted by Nicodem | | Quote: Originally posted by swami.me | | I am new to organic synthesis. I would like to synthesize Methylammonium Acetate crystals by reacting acetic acid and methyl amine solution (40% in
water) at 0C. But I wasn't sure how to get dry crystals. |
It is not called to synthesize crystals, but to grow crystals. This is done by numerous techniques. The most common are the crystallization from a hot
solution by slow cooling and the slow evaporation techniques. For some compounds it is best to use seeds. As for how difficult it is, it depends on
how large crystals you want to grow. You can try letting a solution of methylammonium acetate in ethanol or 2-propanol evaporate from an open beaker
in a dry place (I think methylammonium acetate is hygroscopic). It might give you mm size crystals. |
Thanks for correcting me. I really don't need large crystals. I need the material in crystalline form as I need to do powder XRD and FTIR of MAAc. I
will try method suggested by you if I end up with amorphous material.
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CharlieA
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Perhaps (probably) I am ignorant, but what is the structure of "methylammonium acetate"?
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DraconicAcid
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The cation is CH3NH3(+), the anion is CH3CO2(-).
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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PlatinumLab
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Swami, I find it quite odd that someone with very minimal chemistry knowledge is needing to do XRD and FTIR, on Methylamine, a known drug precursor no
less.
However if that is your simply your intention, Nicodem's technique should do just fine, or even simply gently heating your solution to evaporate, very
gently. Both of these will take quite a long time, but small crystals should result. If your goal is to just isolate the powder form, there are tons
of other techniques that are much faster.
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swami.me
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| Quote: Originally posted by PlatinumLab | Swami, I find it quite odd that someone with very minimal chemistry knowledge is needing to do XRD and FTIR, on Methylamine, a known drug precursor no
less.
However if that is your simply your intention, Nicodem's technique should do just fine, or even simply gently heating your solution to evaporate, very
gently. Both of these will take quite a long time, but small crystals should result. If your goal is to just isolate the powder form, there are tons
of other techniques that are much faster. |
Its definitely for drug use.
Enuf jokes!! I fabricate solar cells based on CH3NH3PbI3 perovskite structures. I get this by the reaction of
Pb(Ac)2 + 3 CH3NH3I ---> CH3NH3PbI3 + 2 CH3NH3(CH3COO)
It is important for me to study the byproduct to understand the perovskite formation mechanism. I am weak in Synthesis but not weak in material
characterization.
If you need any more info on my work, I would be glad to show you my papers.
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swami.me
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Thanks Everyone....This is what I did and I believe I might have partially suceeded
1. Added NaOH to MethylAmine solution. This evolved MeNH2 gas which was then passed through a NaOH column to remove moisture and finally output to a
flask containing 5mM of acetic acid in Toluene.
2. While NaOH did evolve gas the output was low as seen from small bubbles with lower frequency. Stirring the solution did the magic. The reaction
with acetic acid turned turbid, however no solids formed
3. Added more Methyl Amine solution and NaOH and this led to formation of white solids in acetic acid flask.
4. Let the reaction go for 30 mins. Removed the flask and dumped the toluene. The remaining solid was viscous white. However the solid was acidic- I
could easily smell acetic acid.
I am going to try redoing the synthesis with copious amount of NaOh and Methylamine to ensure complete reaction.
What do you guys think?
Swami
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Nicodem
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| Quote: Originally posted by swami.me | | Thanks for correcting me. I really don't need large crystals. I need the material in crystalline form as I need to do powder XRD and FTIR of MAAc. I
will try method suggested by you if I end up with amorphous material. |
If that's all you need the reference material for, then crystal size makes no difference.
Using toluene for forming an ammonium acetate is not commonly the best choice, especially if you want a crystalline product.
Generating methylamine gas from its aqueous solution requires heating. NaOH itself is not enough. It will increase the ionic power, heat up the mix to
some degree and reduce hydration of methylamine, thus liberating some. But you need to apply heat as well, or else you will only release a small part
of methylamine.
You could also do this without gassing. Just add 1.2 eq. of 40% aq. methylamine to acetic acid in 2-propanol. Rotavap, add more solvent, rotavap
again, repeat until you get crystallization. This may or may not work, but it is simple enough to try. Just don't use toluene at reflux like reported
here.
Procedure from EP808826:
[Edited on 24/1/2016 by Nicodem]
…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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