brisance
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Magnesium Nitride
I appologize for asking a question with such a definite answer. I have indeed searched all my resources for the answer, but have come up with none,
so I entreat you to offer me your resources for this specific question:
At what temperature (and possibly pressure, too) does magnesium combust with nitrogen?
Thank you.
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chemoleo
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I am sure this has been talked about somewhere else.. but anyway:
According to Brauer, page 911:
Magnesium shavings (so quite coarse) which were prepared under an atmosphere of argon (it's necessary if you want to prepare PURE Mg3N3) are
reacted with dry N2 at 200 ml/min.
The reaction commences at 400 deg C. The reaction is held at 700 deg C for 3 hours, and for recrystallisation (that's what it says ?!) for 16
hours at 940 deg C. To finish it off, it is cooled with N2 to RT.
Normally, Mg3N2 is made by reacting it with N2 by first getting it to ignite with O2; as soon as the O2 is used up, the nitride is produced. It is a
yellowish green loose powder.
I often thought, magnesium nitride (or the analogous carbon nitrides, or even CaC2) should be great syntheons, i.e. I imagine Mg3N2 reacts with
ethanol (dry) to form triethylamine and Mg(OH)2... I guess many other useful reactions can be done that way too 
Seriously, I have often thought about this: what do you think:
The nitride is an extremely weak acid, ethanol is a much stronger one.
So I should think that the OH reacts with the Mg, forming Mg(OH)2, while the remaining ethyl group reacts with the nitrogen moiety. Since there are
three, it would produce triethylamine.
Anyone got some input on this, the reactions of magnesium nitride?
[Edited on 8-3-2005 by chemoleo]
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halogen
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Could Mg3N2 react with a chlorocarbon and replace with N onto the carbon and form MgCl2?
[edit for clarity]
[Edited on 1-12-2006 by halogen]
F. de Lalande and M. Prud'homme showed that a mixture of boric oxide and sodium chloride is decomposed in a stream of dry air or oxygen at a red heat
with the evolution of chlorine.
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Dr. Beaker
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Some basic chemistry guys...
N-3 is such a powerfull lewis base and this will probably put in shade it's nucleophilicity. I think it'll just deprotonate things up i.e:
N(-3) + ROH -----> RO(-) + NH(-2)
and thus all the way to NH3 with addn. eq. of hydroxyl groups.
with haloalkanes it'll make eliminations (extraction of HX and formation of C=C).
on the other hand the reaction with boranes might be interesting:
N(-3) + 4BX3 -----> N(BX3)4(-) ?
or polymers with addn of X2B-CH2-BX2 to the monoprotonated NH(-2)
[-NH-BX2-CH2-BX2-]n
[Edited on 1-12-2006 by Dr. Beaker]
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Nicodem
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| Quote: | Originally posted by halogen
Could Mg3N2 react with a chlorocarbon and replace with N onto the carbon and form MgCl2? |
No. There would be no reaction unless you find a solvent that is able to solvate Mg3N2. As far as I know no such solvent exists and if it would the
reaction would be elimination (like Beaker explained) except with those alkyl halides that can't eliminate HX (like MeX, BnX etc.).
Mg3N2, like other similar polycrystalline (ceramic) compounds, only reacts as an ionic compound with acids (H2O, alcohols etc.), but will not behave
as a ionic amide in other reactions (unlike sodium amides). A similar situation is, for example, with calcium carbide (CaC2). It reacts rapidly with
weak acids (H2O, alcohols etc.), but it will not react even with benzyl chloride under reflux in any solvent (unlike the sodium acetylides that react
with alkyl halides immediately).
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
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scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
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