JonMc95
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Alkyl nitrite synthesis
Wikipedia: "Organic nitrites are prepared from alcohols and sodium nitrite in sulfuric acid solution. They decompose slowly on standing, the
decomposition products being oxides of nitrogen, water, the alcohol, and polymerization products of the aldehyde."
So I would like to synthesise isopropyl nitrite, I have isopropyl alcohol, sulphuric acid and distilled water.
What I need help with is, does sodium nitrite have to be used in this experiment (NaNO2)?
Surely another nitrite salt would work, let's say potassium nitrite (KNO2).
Also, if I got sodium nitrate (NaNO3), would heating it leave behind sodium nitrite (NaNO2)?
NaNO3 -> NaNO2 + O2 (if this is wrong, please correct me).
Final question, can this be done with potassium nitrate (KNO3)?
KNO3 -> KNO2 + O2.
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Bismuth
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You're correct about the sodium/potassium nitrite production methods but it's not as easy as it sounds. When heating it so it decomposes, some of the
oxygen recombines to form nitrate again. You won't get a pure product by simply heating it in a test tube and decomposing it.
See: http://www.sciencemadness.org/talk/viewthread.php?tid=52 for a bunch of methods on how to prepare these. All in all, having tried it myself, if
you can buy the nitrites, you're much better off in my honest opinion.
Sodium and potassium products are usually interchangeable if you need the anion.
Just to add, remember to balance the equations before you do the stoich.
[Edited on 28-6-2011 by Bismuth]
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kazaa81
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Been wondering about who could be the heaviest alkyl nitrite member...hexyl nitrite maybe?
Or are, say, glycerol and xylitol susceptible enough as alcohols to react just as monohydric alcohols do?
Tried to look on google but couldn't dig out anything.
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Praxichys
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Polyols do indeed form alkyl nitrite esters. Here on the forum, both glycerol and ethylene glycol were used.
http://www.sciencemadness.org/talk/viewthread.php?tid=6395
Polynitrites are probably less stable then mono-nitrites and based on oxygen balance are potentially explosive. It may be difficult to fully nitrite
some of the heavier alcohols. The reaction is analogous to nitration.
The reaction is simple acid esterification and will work on basically all aliphatic hydroxyls. There is no restriction on compound weight, though
eventually you will end up with solids.
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kazaa81
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I see, missed that. Thanks for the info.
Do only the lightest nitrites produce smooth muscles relaxiation and bind to form methemoglobin or do those of polyols too?
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kecskesajt
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I tried to make IPN with homemade nitrite but it just made a black, very unplesant smelly goo instead the sweety nitrite.I wanted but it wont even
ignite.
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Hawkguy
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Does anyone know any more specific guidelines for making Isopropyl Nitrite? I tried making some the other day, and it was unsuccessful. I dissolved
Sodium Nitrite into Sulphuric Acid, and cooled in an ice bath. Isopropanol was added slowly, and the temperature was kept low for about an hour. I
checked for layer separation, and there was nothing. What am I doing wrong?
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Metacelsus
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I did it once a long time ago with hydrochloric acid, and it worked fine. Maybe sulfuric acid doesn't work as well (but I don't see any obvious reason
for this to be true). You could also try changing the order of addition.
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Hawkguy
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Hydrochloric Acid? I thought Nitrite was higher in the activity series than the Chloride anion...
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LearnedAmateur
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Hawkguy - add your sulphuric acid to the alcohol first, the two won't react at lowered temperatures (although if added too quickly, propene will be
formed by dehydration). What is happening is that your nitrous acid is being generated and decomposing before it can form the ester. Upon addition of
the nitrite solution to the acid/alcohol mixture, there should be bubbling and the immediate formation of an alkyl nitrite layer on top of the water -
I managed this reaction, first time, in under 20 minutes (including preparation) so an hour is far too long for this small scale synthesis.
Anyway, nitrous acid is a weak acid whereas HCl is strong (pKa 3.4 vs -6.3, respectively) - all mineral acids will win out over the nitrite anion even
though its beefier cousin HNO3 is one of the strongest common acids, easy to get confused.
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XeonTheMGPony
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A friend asked me to make him some thing of this nature and doing some research I found a novel approach, they used nitric acid, sulfuric acid copper
shavings and then co-distill these in the alcohol.
I have yet not tried it nor to see how many nitrates would be made and so fourth but may be of assistance.
Attachment: Ethyle Nitrite.doc (46kB)
This file has been downloaded 906 times
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