APO
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Allyl Amine from Mustard Seeds/Oil
I want to make Allyl Amine, and I know it can be made by hydrolysis of Allyl Isothiocyanate. Recently I read that Allyl Isothiocyanate can be produced
in above ninety two percent purity by dry distallation of mustard seeds, so naturally I have a couple of questions. Which would be more efficient, dry
distallation of mustard seeds, or distallation of mustard oil? Also, once Allyl Isothiocyanate was obtained, how would one go about hydrolysing it
into Allyl Amine?
"Damn it George! I told you not to drop me!"
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blogfast25
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Hydrolysis to amine:
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV2...
A homogeneous reaction would probably be much faster but would require a solvent that is common to both the allyl isocyanate and the HCl (or another
acid).
With a BP of around 150 C (of allyl isocyanate) steam distillation of mustard oil is probably not going to work. Try cracking mustard seeds, allow to
stand (to allow conversion of the glucosinolate) and try gentle dry distillation. Work up and determine BP.
[Edited on 25-8-2013 by blogfast25]
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Oscilllator
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According to wikipedia, mustard oil IS the 92% Allyl Isothiocyanate that you are looking for. So no need to do a dry distillation. I think.
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DJF90
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Quote: Originally posted by blogfast25  |
With a BP of around 150 C (of allyl isocyanate) steam distillation of mustard oil is probably not going to work.
[Edited on 25-8-2013 by blogfast25] |
And on what basis do claim that..?
[Edited on 25-8-2013 by DJF90]
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blogfast25
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| Quote: Originally posted by APO | | Well, this is starting to be less pratical than I thought. Alternatively, could Allyl Alcohol be reacted with Hydrochloric Acid to form Allyl Chloride
and then be reacted with Ammonia to form Allyl Amine? |
Possibly but these questions really belong in the organics section. I think the some of the wizzkids over there will be able to help you better.
It could be worth asking if the hydrolysis of allyl isothiocyanate to allyl NH2.HCl could be carried out in (diethyl) ether or ethanol, for
instance (HCl has some solubility in both). Hydrolysis in a homogeneous reaction mix is usually much faster than in a two phase system where the
reactants are squarely in separate phases and the reaction can only proceed at the interface.
[Edited on 25-8-2013 by blogfast25]
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APO
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Oscilllator, distillate of mustard seeds is 92%+ Allyl Isothiocyanate, mustard oil is the resulting liquid from crushed mustard seeds, it is not
distilled, just filtered.
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kristofvagyok
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Tried it? Of is there any reference for that? -except Wikipedia.
I found a paper about this: Journal of the American Oil Chemists’ Society September 1964, Volume 41, Issue 9, pp 599-602
Where they write this: Essential Oil Composition.
A typical chromatogram of the essential oil of
oriental mustard indicates the following composition:
carbon disulfide 1%, allyl thiocyanate 9%,
allyl isothiocyanate 90%
A recipe:
The seed was
tempered by addition of water to 7% moisture and
rolling in a sealed drum for 2 hr. Flakes of 0.005-in.
average thickness were prepared either by cracking
on corrugated rolls set at 0.002-in. clearance followed
by rolling through smooth rolls or by a double pass
through smooth rolls. About 4,000 g of the prepared
flakes were charged to the converter-cooker and
moistened to 30%. After mixing at room temp for
5 rain, the charge was heated to 55C and held at
this temp for 15 min to promote enzymatic hydroly-
sis of the thioglucoside to isothioeyanate. The myrosin
enzyme system present naturally in the seed was
sufficient to catalyze the reaction. Following this
conversion period, live steam was admitted to the
charge and the volatile essential oil was distilled at
100C. The essential oil was recovered from approx
2,500 ml condensate by centrifuging and removing
as the lower layer. Ca. 80% of the total analyzable
isothiocyanate in the seed was recovered by this tech-
nique; the remainder was discarded in the aqueous
phase. When recovery was conducted under vacuum,
a solid carbon dioxide trap served to condense the
essential oil.
Cheers.
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APO
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Could Dimethyl Sulfoxide be used for getting the Hydrochloric Acid and Allyl Isothiocyanate into one phase?
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kristofvagyok
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| Quote: Originally posted by APO | | Could Dimethyl Sulfoxide be used for getting the Hydrochloric Acid and Allyl Isothiocyanate into one phase? |
Dimethyl sulfoxide and hydrochloric acid yields a sulfenium ion, for more information see the wiki page of Tröger's Base. So it's not a good idea.
Also it's really hard to get out DMSO from your reaction mixture, this is why it is only used if it nothing else works.
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APO
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That's unfortunate, anything that could get the two phases to mix?
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ziqquratu
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An isothiocyanate might just react with an alcohol to give a carbamate, which could be quite stable (especially an ethyl carbamate if you used
ethanol). You CAN break them apart, but it's not always simple!
The org syn prep that blogfast posted looks about as simple as a procedure comes - I certainly wouldn't be trying to improve on it! If you're
concerned about heating over a flame, I see no reason that such heating would be required - a hotplate should do the job just as well. Likewise, a
mercury sealed overhead stirrer seems unnecessary - a magnetic stirrer should work quite well.
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DJF90
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I gotta disagree on the last one Ziqquratu; certainly dispense with the mercury sealed shaft but mechanical stirring isn't really optional here,
particularly on a readonable scale due to the biphasic nature of the reaction mixture.
A co-solvent like THF may be possible. Cleavage may be an issue though. Diethyl ether might also be a possibity, but the low bp and poor water
miscibility might be an issue, although it will dissolve 7% water, maybe a little more or less due to the HCl.
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ziqquratu
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I don't know - I've done large scale (>3L) biphasic reactions before, using nothing but a ~35mm long egg shaped stir bar, and it's always worked
well for me. Add in the fact that this mixture would be boiling and so mixing itself to some degree (mine were always room temp), and I'd be very
surprised if you couldn't stir well enough! Sure, if you had particularly viscous liquids, or if you had a suspension of solids, there's no way a
magnetic stirrer would work on that scale, but for this job, I'd predict no problems.
Looking at the procedure again, though - they use the overhead stirrer for the distillation, which is monophasic anyway! They don't actually use ANY
stirring during the hydrolysis step. So, adding magnetic stirring to the hydrolysis might just speed things up a little; likewise, magnetic stirring
during the distillation should do just nicely.
Ether would probably do no good - it's nowhere near soluble enough to improve the phase transfer, particularly once it's dissolved a heap of poorly
water soluble material! THF would certainly improve phase mixing, but I agree that cleavage might be a problem (although it shouldn't happen to too
great an extent).
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DJF90
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That'll serve me right for not looking at the preparation in question...
I can't beleive they'd try this without a good mech stirrer. Its the first thing that comes to mind when biphasic reaction pops up. Kudos to you Ziq
for being ballsy enough to use a mag stirrer for these types of reactions (especially on the scale you describe!). I wonder if appropriate mixing
would bring that reaction time down from 15 hr to significantly less.
I agree with you on the ether, on checking the figures I got the solubility wrong; 1.3%w/w water in ether, but 6.9% ether in water. Given all the
other junk in there, it'll be next to useless. Given this prep at OrgSyn (http://www.orgsyn.org/orgsyn/prep.asp?prep=cv2p0571) the use of THF may also be useless.
[Edited on 22-9-2013 by DJF90]
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