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Author: Subject: The short questions thread (1)
Panache
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[*] posted on 11-12-2008 at 17:55


what is the most likely culprit for tubidity in my sodium methoxide solution. I am making the methoxide by adding sodium metal to methanol, the methanol was dried over potassium carbonate, its density coming in at 0.78g/l, the sodium was patted to absorb excesss mineral oil then rinsed in methanol then added to fresh methanol. My only guess is that some paraffin was not effectively removed and this is forming a verry finely divided suspension, to test this i allowed a hunk of sodium to half dissolve before adding it to fresh methanol. All glassware was dry however what would the visual result be of using less than optiomally dry glassware i imagine one could not distinguish between a methoxide/hydroxide solution in methanol and a methoxide solution in methanol.



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Fleaker
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[*] posted on 11-12-2008 at 17:59


A shot from the ship here, but I think it is probably carbonate from minuscule amounts of CO2 reacting with the alkoxide.
Whenever I make methoxide solutions (especially the more concentrated it gets) I always notice this turbidity too whenever it is exposed to air. On one occasion, I made up a methoxide solution in MeOH and did it under argon and it was clear. Convinced me!




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Panache
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[*] posted on 11-12-2008 at 21:09


Quote:
Originally posted by Fleaker
A shot from the ship here, but I think it is probably carbonate from minuscule amounts of CO2 reacting with the alkoxide.
Whenever I make methoxide solutions (especially the more concentrated it gets) I always notice this turbidity too whenever it is exposed to air. On one occasion, I made up a methoxide solution in MeOH and did it under argon and it was clear. Convinced me!


Voila!, under argon tis also clear for me, thanking you!




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[*] posted on 11-12-2008 at 22:47


Further to my vacuum questions, are there any good ways to improvise a cold trap? Just gave my medical pump a run and was boiling water at room temp with a change of oil :D
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Panache
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[*] posted on 12-12-2008 at 02:37


Quote:
Originally posted by raiden
Further to my vacuum questions, are there any good ways to improvise a cold trap? Just gave my medical pump a run and was boiling water at room temp with a change of oil :D


Man i have ben hanging out to give this tip. I use an ice-cream maker for my benchtop vac-pump cold trap. its probably the best thing i've ever improvised. It sits at -45. I turn it on at the start of the week and off at the end of the week, it has a basin of 1.5l in size which perfectly fits a 1L schott bottle and about 10mm of space around it to fill with methylated spirits as the cold bit. I simply have a bubbler head on the bottle. It's important to have any bleed valve (that bleeds to atmosphere) you might have between the cold trap and the pump, otherwise you consume all your cooling capacity cooling down the bleed air.
Of course it has it limitations being only at -45 but it beats the hell out of dry-ice or liq N2 for convenience. Its an italian thing but sold throughtout australia, i got mine second hand for like $30 because the stiring mechanism was broken, but given i wasn't making ice cream iit really didn't matter. Apparently this model always breaks stirrers so you should find one easily. The brand name is Nimox.




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[*] posted on 14-12-2008 at 07:44


Ethylamine Synthesis?

I've searched fo a synth for this, wikipedia is a little lacking, would be interested to know how people here make it
thanks in advance
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[*] posted on 14-12-2008 at 09:29


I don't thin k many people make it themselves, this is the kind of chemical that is much easier to purchase than to make...

Best options seems to me as been ethylation of protected ammonia, forming either the benzaldimine, or the phtalimide.. Ethylating acetamide or formamide with EtX, KOH and a PTC might be another good option, hydrolyzing the amide and distilling the ethylamine solution out.. There was a thread on diethylamine synthesis where I gave a few references on the subject, check it out: diethylamine synthesis.
I think there are some vapor methods using ethanol, ammonia and some catalyst, although you would surely obtain a mixture or mono-di and perhaps triethylamines.




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DJF90
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[*] posted on 14-12-2008 at 10:23


How about an Sn2 reaction between ammonia in an appropriate solvent and an ethyl halide. A large excess of NH3 should be used to prevent multiple N-subtitutions (forming di and tri ethyamines, and quaternary ammonium salt).
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[*] posted on 14-12-2008 at 10:49


No, unfortunaly this reaction cannot be used in a preparative way, there will always be various poly-alkylation products... Well, as far as I know.

I would rather concentrate on reactions producing only the primary amine, as seperating them will not be easy.




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[*] posted on 14-12-2008 at 17:47


Phthalimide process.

Phthalic acid or anhydride + ammonia --> phthalimide (or buy phthalimide itself)
Phthalimide + base (pKa ~ 9) + electrophile (e.g. bromoethane) --> N-ethyl phthalimide
Hydrolyze alkyl phthalimide with dilute H2SO4. Freebase monoalkyl amine, purify etc.

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[*] posted on 15-12-2008 at 14:58


Does anyone have any information regarding extracting PTCs from shampoos etc?

Formula409.
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[*] posted on 15-12-2008 at 15:03


What PTCs are even in Shampoos?
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[*] posted on 15-12-2008 at 15:12


Quote:
Originally posted by kclo4
What PTCs are even in Shampoos?

I do not know. I have read several forum posts which mention extracting them from shampoos and conditioners with no citations :( Hmm. Will try and post links, however, with most things when you're looking for it you can never find it.

Formula409.

[Edited on 15-12-2008 by Formula409]
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[*] posted on 16-12-2008 at 16:47


My shampoo lists ammonium laureth/lauryl sulfate, polymethacrylamidopropyltrimonium chloride and other chemicals that sound rich with alkyl chains. Detergents, especially antibacterials, often contain quaternary amines, though usually much larger than your average PTC, things like (12 to 18)-alkyl phenylethylmethylammonium.

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not_important
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[*] posted on 16-12-2008 at 17:03


Quote:
Originally posted by Aubrey
Ethylamine Synthesis?


Might consider the Hofmann rearrangement of propionamide.

Having said that, I've used the reaction of ethanol with ammonia over hot Ni-Cu to get a mix of all three ethyl amines and fractionated them. Wintertime in an unheated area and it's just separating three compounds that have boiling points about 40 C apart.
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[*] posted on 16-12-2008 at 17:32


Quote:
Originally posted by Aubrey
Ethylamine Synthesis?

I've searched for a synth for this, wikipedia is a little lacking, would be interested to know how people here make it
thanks in advance


I'm not sure, This is how I would attempt to make it. I beleive Acetaldehyde + Ammonia might form a complex similiar to that of hexamine, which is formed from Formaldehyde and Ammonia.
You could then react that compound with some hydrochloric acid as they do hexamine in the methylamine synthesis. Look around on the Rhodium Archive, It has some information on making Methylamine.

If this reaction worked, it would allow using aqueous reagents, making it easier to produce mostly Ethlyamine, instead of the other amines that can form as well.
Ammonia and Ethanol seem like it would be nice, if you could regulate it to form mostly Ethylamine however.

Hoffman degradation would probably be the best if you could find the appropriate amide, which might be tricky, however acetaldehyde might be a bit tricky to get also.
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[*] posted on 16-12-2008 at 23:17


Quote:
Originally posted by Aubrey
Ethylamine Synthesis?


Theres over 800 articles on scifnder reporting its preparation or at least as a product of a reaction. 145 reactions are given of which 100 are attached, they seem mainly by way of hydrogenation of acetonitrile.

There was only one reporting an ethyl analogue of hexamine and then no preparation, and was only a Jap patent.

Attachment: ethylamine product reactions.pdf (250kB)
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[*] posted on 17-12-2008 at 01:05


Nitroethane could possibly be reduced to ethylamine.
Al amalgam or Al isopropoxide would probably do it.

Metaldehyde and ammonium nitrate would possibly react
giving a nitrate salt which could then be basified to
free the volatile amine. This is not something I have ever seen described
but there is an analogous reaction for methylamine.

These reactions could be hazardous, but manageable.

You would have to distill out the free amine and
absorb it in water.

[Edited on 17-12-2008 by Rosco Bodine]
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[*] posted on 17-12-2008 at 09:54


I'm sure to many nitroethane is more preciosu than ethylamine :) I think the idea of oxidizing ethylamine to nitroethane popped up a few times!

I'm very impressed by the fact that Not_important succeded with vapor phase method, it would seem it is a very usefull procedure as diethylamine and triethylamine are also valuable reagents. I had just assumed seperating ethylamine and diethylamine would be very tricky..

How did you prepare your catalyst Not_important?




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[*] posted on 18-12-2008 at 13:50


question regarding spongy copper being used as electrodes, well this is what an article has implied. I have somewhat sorted this out.

[Edited on 19-12-2008 by brew]

[Edited on 19-12-2008 by brew]
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[*] posted on 20-12-2008 at 04:43


What would o-Phenylenediamine be called if it had a methylamine attached at both sites instead of the amine......solo

[Edited on 20-12-2008 by solo]




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[*] posted on 20-12-2008 at 05:13


That would conceivably be N,N'-dimethyl-o-phenylenediamine, or better yet, 1,2-bis(methylamino)benzene. :)

sparky (^_^)




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[*] posted on 20-12-2008 at 05:37


......follow up question regarding amines

if this is true,

o-Phenylenediamine condenses with ketones and aldehydes to give rise to Schiff bases.

.......source,

http://en.wikipedia.org/wiki/O-Phenylenediamine

....then can this also be true?

N,N'-dimethyl-o-phenylenediamine condenses with ketones and aldehydes to give rise to Schiff bases.




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[*] posted on 20-12-2008 at 15:16
Industrial Chemistry Question


Re: The Sodium-mercury amalgam created by electrolysis of a saturated NaCl solution - applicable to Li ?

Very facile process, and although you do need to distill off the mercury at the end to get the pure sodium out, it does work. It was originally used to make NaOH, but instead of adding water at the end, you can just remove the mercury.

I was wondering, I was looking at the LiCl/KOH electro process and I wondered if anything analogous to the sodium process could be done here? I am guessing I would have found something already if so... but I do know that Li/Hg forms an amalgam when mixed, and so the stopping block would be the solvent, electrochemical problems.

That is to say, is there a solvent that would free the Li ions, allow for electro amalgamation at a mercury cathode, and release Cl gas as a byproduct, meanwhile amalgamating the Li ions into the mercury, or is that just wishful thinking?

For that matter, what about KCl?

Pointing me at an Electro chem reference that resolves this would be a fine answer, as well!

Thanks :)
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[*] posted on 20-12-2008 at 22:55


Lithium amalgam is less reactive towards water than sodium amalgam, you should be able produce low concentrations of Li without much trouble. Or at least much trouble from a technical standpoint, as Li-6 concentrates in the mercury the process is used to produce lithium enriched in Li-6 for tritium production, and thus falls into the arena of nuclear weapons technology.

here's a little on making Li-Hg amalgam and extracting Li metal from it.

Attachment: 80971.pdf (551kB)
This file has been downloaded 874 times

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