thereelstory
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Has anyone made sodamide?
by mixing na and anhydrous nh3?
also, what cool experiments could be done with this Sodamide?
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Picric-A
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You cant just 'mix' Sodium and anhydrous ammonia, the reaction must be conducted at high temp and probably pressure.
As for uses, do some research!
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DJF90
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Whoa steady on... You CAN just mix sodium and anhydrous liquid ammonia; do YOUR research Picric-A! Initially you get the blue colour of solvated
electrons but eventually this fades and what is left is a solution of NaNH2 in anhydrous liquid ammonia. Quoting Feiser:
| Quote: | | Most laboratory procedures are based upon the discovery by Nieuwland and co-workers that the reaction between sodium and liquid ammonia is
accelerated markedly by a black catalyst prepared originally by the reaction of a ferric salt with oxides of sodium in liquid ammonia. Liquid ammonia
(500ml) was stirred at -33*C and treated with 0.3g Fe(NO3)3-6H2O and then with 1g of sodium. Air was bubbled through the mixture to discharge the
initial blue colour and produce a black precipitate of catalyst. Additional sodium (25g), added portionwise was then consumed in about 20min. with
discharge od the blue colour and production of a grey suspension of sodium amide. The solubility of sodium amide prepared in this way is 1 mole per
liter of liquid ammonia at -33*C. |
So perhaps you can familiarise yourself with the known literature before saying the reaction "must" but conducted at high temp and perhaps pressure.
There is usually "more than one way to skin a cat", as it were...
As for uses, Feiser details 6 pages worth of material. I'm sure you could find some if you looked. I've been kind enough to attach the monograph from
"Handbook of reagents for organic synthesis: Acidic and basic reagents".
[Edited on 20-5-2010 by DJF90]
Attachment: Acidic and Basic Reagents - Sodamide.pdf (327kB)
This file has been downloaded 2388 times
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Picric-A
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The sodium/ammonia complex takes a while to fade and so it is NOT the best method of preparing sodamide.
Brauer's prep outlines passing NH3 over heated Na then once fully reacted leave to cool in a steady stream of NH3, leaving pure white sodamide.
The Feiser prep leaves you with a solution of (1molar) sodamide to dispose of- i doubt anybody has the equiptment to safely deal with that or in an
enviromently friendly manner.
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DJF90
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Nobody said it was the best way to make it, but "best" is surely a matter of opinion depending on apparatus available and ease of preparation. If you
can make liquid ammonia, then this is almost certainly the safest method, and gives material of adequte purity for all but the most demanding
analytical uses. The Feiser prep gives sodium amide which has a solubility of 1 mole/liter of ammonia, but more than that is produced as it clearly
states you obtain a grey suspension, i.e. there is more sodamide than can dissolve - however your comment about disposal of a 1M solution is minor as
you would scale down suffuciently to make the amount of reagent needed for your synthesis; typically <10mmol.
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panziandi
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Firstly: I really think that this thread should be in the beginning section!
Secondly:The is nothing more anoying than reading the word "cool", in a context other than that relating to temperature, in the same sentence as
sodamide! Sodamide is a particulrly strong base, it reacts violently with water releasing toxic and irritant fumes of ammonia. It also oxidises slowly
on storage forming shock sensitive explosive peroxides! This is not really something to be made and experimented with by a k3wl!
Thirdly: I couldn't resist... Picric-A... Read before posting! DJF90 clearly states in the quote from Feiser that the sodium is consumed in 20mins
with a precipitate of sodium amide, there is also some solvated sodium amide in the ammonia solvent. Indeed if you simply mixed sodium with liquid
ammonia the solution is fairly stable for a time, that is why the ferric catalyst is added to reduce reaction time to 20mins, which, in all fairness,
is a hell of a lot quicker than the method of heating sodium in a stream of ammonia. In addition the method of heating sodium in ammonia can also form
sodium hydride which needs to be removed by adjusting the temperature in a second round of heating. So, why not do some research yourself before 1)
posting uninformative remarks and 2) posting pseudo-knowledge.
Because of the sodium amide's tendancy to form explosive peroxides on storage, as well as with the fact that it is dangerous when wet and hygroscopic.
Many university undergraduate labs prepare in situ by solvating sodium in liquid ammonia since this removes the storage and handling hazards of the
solid material. Together with the fact that many students in a chemistry undergraduate lab are not chemists at heart, they often make handling errors
when weighing etc, it wouldn't take a genious to envisage cross contamination into a jar of sodium amide something that would be incompatible...
In my honest opinion, if thereelstory is not a k3wl and is looking to do some interesting organic chemistry with this strong base rather than "cool"
stuff, his best bet would be to form it in situ and not to isolate the sodium amide for storage.
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Picric-A
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I know some of the sodium amide precipitates however SOME also stays in solution and i would call a solution of sodium amide (corrosive, toxic) in
liquid ammonia (toxic, corrosive, harmfull... etc...) a serious hazard to have around/ store/ destoy and i dont see why anybody would pick this
method.
Of course there is virtually no means of us in the UK purchasing liquid ammonia however i hear it is fairly readily available in the USA for farms and
so if it is readily avaiable then i guess i dont see why not use it! (liquid ammonia is used by meth cooks for Birch reduction in the USA)
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Sedit
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The complex also forms NaNH2 in the presence of Styrene and the references for this reaction can be found either in my Li[NH3]4 thread or others here
on the board. There are a few catalyst that can perform this reaction to NaNH2 from the complex and if you do a search for inhibiters of the birch
reaction you will find the government spent sometime trying to find things that quickly destroyed the Sodium or Lithium complexes to prevent its use
in the manufacturing of Methamphetamines.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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DJF90
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You don't have to buy liquid ammonia; -33*C is pretty mediocre and you can readily condense ammonia gas using dry ice/acetone or even a salt-ice
mixture. Like I said before, the solution obtained is 1M which is fairly reasonable, and you would only make as much as you would need for the
reaction in question. Both methods would involve decent ventilation but the high temperature route also has potential for explosion, as ammonia forms
explosive mixtures with air (between 15 and 28% IIRC).
Panziandi is quite right when he says that this method is quick and reliable. Often you need a solvent for your reaction and selecting one for sodium
amide can be tricky; when made in situ the liquid ammonia is the solvent and so this is not an issue, and the low temperature is generally required
when deprotonating with a strong base anyway. You definately wouldnt *store* the solution as this would require a freezer suitable for purpose; it's
easier to just make it as needed. If solid sodium amide is needed, one can allow the solvent to evaporate to leave the material behind as a slightly
grey powder.
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Picric-A
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DJ- Both procedures have potential for explosion. In the high temp reaction it is true the temperature is off-putting however dont forget only pure
NH3 is being tapped in and so no fuel/air mixtures are being produced-especially those as obscure as 15-28%.
The risks of the liquid NH3+Na method is well known as it is often a reason for meth labs 'random' explosion- runaway reaction.
I have to agree however, the latter would be better for producing <3g quantities.
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DJF90
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You're missing the point Picric-A; when you're pumping the ammonia in to the apparatus, air is already in there. You may argue that with a tube this
is not much of an issue and you're right, but for producing quantities via the hot method you typically use an oven as in "Inorganic Syntheses", in
which the air might not be as readily displaced by the ammonia gas as you'd like.
Explosion from the liquid ammonia method is negligable; we're chemists here, not meth cooks, and so will know external cooling is required. Chances
are you'll already have the flask in a (dry) ice bath anyway in order to help condense the ammonia and/or to minimise evaporative losses (this
shouldnt be an issue with a dewar condenser though but some methods advocate allowing the ammonia to boil off during the preparation and topping up as
required). Portionwise addition od sodium metal (also mentioned by Feiser) also helps with this issue.
I'm going to disagree with you again on your final point; for preparation of <3g quantities, especially if purity is an issue, the hot method would
be more appropriate. 3g worth of material can be made readily from a quantity of sodium in a combustion boat in a tube. Again, this may not be the
best method from a safety point of view if you have access to liquid ammonia (or if you condense it yourself), but on such a scale it is a minor
problem (recall my comments about the tube above) readily overcome and gives a purer product (necessary if you're worried trace Fe compounds may
interfere with your reaction).
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The WiZard is In
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When thrown into water a most lively action occurs, just as if the
crystals had consisted of globules of red-hot metal, violent hissing
occurring without the evolution of any gas except water vapour.
The solution is found to contain only soda and ammonia.
Sodamide may be prepared in much larger quantities and in very
much less time by allowing .......
http://tinyurl.com/2aqhbsa
Didn't take a second or two to find this at Google.com/books
and a SL of other stuff.
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panziandi
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Also do not forget that with the method Picric-A suggests:
Na + NH3 => NaNH2 + 0.5H2
Some of this H2 is consumed forming NaH but some of it will escape. Note that both H2 and NH3 will form explosive mixtures with air. The reaction time
is much longer, equipment is not the bog standard quickfit etc and will require a much larger amount of gaseous ammonia (in my opion but I haven't
done the maths).
Reaction of sodium with liquid ammonia with a little ferric nitrate is the STANDARD method of preparing sodium amide for use in the lab. Liquid
ammonia is both a reactant and later a solvent for the reaction. On work up the liquid ammonia is evaporated off and the follows standard work up.
Much less hassle and much less time.
Liquid ammonia is easy. Simply pass ammonia into a flask cooled with a freezing mixture (normally dry ice-acetone) at first it's tricky to get it to
condense but once a small amount has liquified the rest soon follows.
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Sedit
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Why all the talk of Liquid ammonia when it should work equally as well using a complex with Na using the gas form of ammonia. Then one would just have
to bubble NH3 into Et2O and stir and the complex will rise to the surface for decanting. It would make the process even easier since ice and salt
water bath is plety cold enough for this and since your going for NaNH2 cooling may not even be needed at all, just feed in NH3 until all the Na is
consumed and precipitated as the amide.
In theory it should work rather well for the production on a small scale and Iv been planing it for sometime with LiNH2 but have had other focus
everytime Iv made the Lithium complex such as studing its stablity and properties while also attempting to streamline the synthesis.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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franklyn
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http://en.wikipedia.org/wiki/Sodium_amide
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv3...
.
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ScienceSquirrel
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I have made sodium amide by reacting sodium with liquid ammonia as described above.
Cylinders of ammonia gas are available quite readily in the UK and the gas can be condensed in a flask using a dry ice / acetone cooling mixture.
There is nothing about the reaction that a competent undergraduate could not achieve given the resources.
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Barium
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Perhaps UK is the exception to this law of physics, but everywhere else in the world a commercial cylinder of compressed ammonia actually mostly
contains liquid ammonia. Just get the right type of equipment to remove it in the liquid form.
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Anders Hoveland
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Quote: Originally posted by DJF90  |
| Quote: | | Most laboratory procedures are based upon the discovery by Nieuwland and co-workers that the reaction between sodium and liquid ammonia is
accelerated markedly by a black catalyst prepared originally by the reaction of a ferric salt with oxides of sodium in liquid ammonia. Liquid ammonia
(500ml) was stirred at -33*C and treated with 0.3g Fe(NO3)3-6H2O and then with 1g of sodium. Air was bubbled through the mixture to discharge the
initial blue colour and produce a black precipitate of catalyst. Additional sodium (25g), added portionwise was then consumed in about 20min. with
discharge od the blue colour and production of a grey suspension of sodium amide. The solubility of sodium amide prepared in this way is 1 mole per
liter of liquid ammonia at -33*C. |
[Edited on 20-5-2010 by DJF90] |
This is an excellent reference. I am surprised. This should be very useful to make sodium azide. There are two main reactions for this. One is sodium
nitrite warmed with hydrazine, the other is sodium amide and nitrous acid. If I can skip the hydrazine, this will be much easier.
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AndersHoveland
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Solvent for sodium amide
Is anyone aware of other solvents that can actually dissolve sodium amide, without reacting with it?
Anhydrous liquid ammonia is usually employed for such reactions, as this seems to be the only liquid which can dissolve sodium amide without reacting
with it, but this solvent is extremely inconvenient for a variety of reasons.
Ammonia has a boiling point of minus 33 degrees Celsius, which means "dry ice" (frozen CO2) needs to be used to keep the ammonia cold. Liquid
anhydrous ammonia is mildly corrossive and can cause severe chemical and cold burns on contact with skin. The liquid gives off of poisonous fumes,
which can result in unconsciousness, or even death in high enough concentrations in air. Some reactions involving sodium amide require heat, which
necessitates pressurizing the liquid ammonia. This requires the proper reaction vessel and is potentially dangerous.
Nearly all other solvents react with sodium amide. Alcohols, ethylene diamine, analine, hydrazine*, pyridine, and N,N-diisopropylethylamine all react
with the amide ion.
Frequently, a dispersion of sodium amide in a hydrocarbon solvent is used for reactions. As the mixture is actually a suspension, the sodium amide is
not actually dissolved.
The only thing I can think of that might work as a solvent is something like an alkyl zinc amide. CH3CH2CH2CH2ZnNH2
*Sodium hydrazide NaN2H3 is a pale yellow crystalline compound which is pyrophoric and can explode on exposure to air, and explodes violently when
heated above 100 C. It can be produced by gradually addition of drops of hydrazine hydrate into a suspension of sodium in ether, then heating in the
absence of oxygen. Otherwise hydrazine reacts very vigorously with sodium metal, producing only hydrogen and ammonia. For the reaction between sodium
amide and anhydrous hydrazine, it was found necessary to use the sodium amide in finely divided form, as otherwise it will react only very slowly with
the hydrazine because a protective coating of the sodium hydrazide forms on the surface.
[Edited on 13-4-2011 by AndersHoveland]
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RiP057
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very true if you cool the cylinder down and then invert it and open up it usually comes out liquid or so Ive heard.... but this thread looks like it
is chock full of people speaking out of there arse, but alas thats what the internet is for innit?
I did have a lecture bottle once of ammonia, and I actually had to keep heating it up so it would gas out the ammonia for when I was removing it from
the cylinder (gas form) it kept cooling the remaining down to the boiling point which is quite cold....
Also try buying ammonia in the US and see what happens...... especially if you tell them you are dissolving sodium or a metal in it 
However I like the use of ammonia hydroxide dripped over a bed of potassium hydroxide will gas ammonia right out.... best way to create ammonia gas in
the lab....
and for small amount I like the sodium straight in anyhdrous liquid ammonia best.....straight forward
[Edited on 16-4-2011 by RiP057]
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RiP057
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why not use benzene as a solvent??? I know it wouldnt solvate it very much, but it would a little
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Eclectic
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If you have good ventilation, delivering liquid anhydrous ammonia from tank bottom directly into a dewar works just fine. The heat of vaporization
is high enough that boiling off a small amount cools the remainder. I've seen a sodamide prep done this way.
Azides from hydrazine and nitrite seems much less hazardous.
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AndersHoveland
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Sodium metal and dry ammonia gas, when heated to 320-350degC, react to form sodium amide and hydrogen. The reaction proceeds around 5 times faster by
bubbling the anhydrous NH3 gas into the molten sodium (heated between 300-350degC) for two hours. Interestingly, below 250 degC, an unknown substance
with a lower proportion of nitrogen is obtained. After complete reaction of the sodium, the unknown product did not produce hydrogen gas on reaction
with water. With the reaction conducted at 200degC, the product contained 71.2% sodium by weight and 23.4% nitrogen. This possibly suggests formation
of some Na2NH. However, this observation was published in the early part of the century (without modern analytical equipment) and there does not seem
to be any other published detailed investigations into the unknown product of this reaction.
The "Concise encyclopedia chemistry", by Mary Eagleson, claims that, "sodium amide, m.p. 210C, sublimable in vacuum, decomposing above 500C to sodium
imide, Na2NH, and then to sodium nitride, Na3N, and ammonia".*
It also says that sodium amide “is produced…by allowing the blue solution of sodium in liquid ammonia to stand. This slowly loses color and
develops hydrogen (the reaction is more rapid in the presence of catalytic amounts of iron)…”
So apparently a catalyst is not absolutely required for sodium to react with cold liquid ammonia, the reaction is just very slow.
*However, I have severe doubts about the accuracy of the "sodium imide" and "sodium nitride".
A recent article (Synthesis and characterization of amide–borohydrides: New complex light hydrides for potential hydrogen storage, Philip A. Chater,
2007) claims that "Sodium imide is unknown". Sodium nitride is very unstable, decomposing into its elements at only 87 °C. Sodium metal cannot be
made to react directly with nitrogen, and thermal decomposition of sodium azide only produces elemental sodium and N2.
Investigations by Titherly, C.A. Kraus, and William Argo showed that molten fused sodium amide, even when free from traces of sodium hydroxide, both
very slowly dissolves metallic platinum, and catalyzes the partial decomposition of molten sodium amide. Using platinum black and fused sodium amide,
the platinum slowly dissolved, and the color turned first red, then brown, and finally black, with apparent increased viscosity. The evolution of gas
from the reaction was slow at 210C but increased rapidly with increased temperature. After heating for 14 hours at 300C, the gas evolved was almost
entirely NH3. The solid product remaining was found to contain 1.658 moles of sodium for every mole of nitrogen present in the compound (sodium amide
contains 1 mole of sodium for every 1 mole of nitrogen).
The fact that no nitrogen was evolved during the partial decomposition, and that the reaction product only produced NH3 when later reacted with water,
suggested the formation of either some sodium imide and/or sodium nitride, although neither of these were isolated.
[Edited on 16-4-2011 by AndersHoveland]
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woelen
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Thread Split
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