Fantasma4500
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Ispropyl Nitrite synth now requires heating?
So, im gonna start off with saying the NaNO2 im using i made myself by thermal decomposition of NaNO3, i have done this with quite an amount of NaNO3
so far and got the whole deal under control, i have tested the finished NaNO2 with conc H2SO4 and copper wires and it yields a very boring and mundane
reaction, a slight bit of NO3 is no issue and is natural to occur as NO2 absorbs oxygen from air over time.
Anyhow- to the point of this thread, long ago when i was much less experienced i prepared a nice heap of IPN, the reaction was quite swift and i used
50% H2SO4 with bought NaNO2 and same grade of isopropyl alcohol as i do today
back then when i added the reagents it heated up well and produced visible NOx fumes
this is no longer the case, and i have done this reaction a bunch of times with more and more resistance, as i from vasodilating properties of the
mixture in the flask noticed there surely was some IPNitrite i decided to pull 50mL into my new 100mL flask and see if i could lure any of it out, and
as its heating up to around 60-70*C its now turning into the characteristic HNO2 color, despite the NaNO2 had been predissolved and whats worse, i had
zero heat being produced when i cautiously poured the IPA + H2SO4 with NaNO2 solution
but its quite evidently now generating HNO2
is my memory really that bad, did this always require heating and are all the preparations online bogus? is it possible that all the synths have been
edited, and that lining up with my memory being entirely wrong
i have had many reactions working against me and even some being entirely impossible no matter how far i stretched it, but this reaction is known to
require cooling as the heat produced is quite frightening and the thing might turn into a runoff reaction if it gets just a bit too warm
im just wanting to hear if other people are experiencing preparations changing personality overnight or if anyone has been around IPN synth lately
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DavidJR
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No, you need to keep it ice cold because HNO2 is very unstable at room temperature
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Tsjerk
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I remember adding the alcohol/96% sulfuric mixture ice cold to ice cold nitrite in water. Remember it is a esterfication. You want as little water as
possible, you do need some however as you need to keep the nitrite dissolved while having a homogeneous mixture. Also you don't want your HNO2 too
concentrated and dissolved in as much water as possible.
On Prepchem there are a couple of different preps with alcohols, sulfuric (or HCl) and nitrite, none of them uses diluted acid, and the one using HCl
is low yielding.
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njl
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Can you outline the thermal decomposition to nitrite? I've seen several threads on here with conflicting info about this procedure and Wikipedia/refs
don't seem to corroborate either.
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Fantasma4500
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using HCl it now appears to be working out, im not chilling it but im adding HCl to NaNO2 / IPA one "whoops" at a time, i have seen the HNO2 persist
even with pretty high temperature, which shouldnt be possible, the HNO2 having a lightblue color, distillation removed this from both solutions
as for the decomp of NaNO3 into NaNO2, its quite simple, it yields oxygen
NaNO3 --> NaNO2 + ½O2
some sodium oxide may be formed too, but also some small amounts of NOx appears to form as the stainless steel container turned into a very neat
superblack, oxygen at high temperature doesnt do this afaik
maybe i used too much water, but it just doesnt add up still, the HNO2 should react somewhat fast with the IPA, and i followed recipe for it, i also
had a batch where even heating the NaNO2 slurry with acid in it and IPA didnt create anything at all
also NaNO2 solution turns into some type of a thin gel as IPA makes NaNO2 insoluble in water
one time i managed to offend it enough to runoff it didnt cause any NOx fumes, but rather the IPN just boiled out? maybe the way to go is to just
throw this into a 500mL flask, attach distillation bridge and pour it all together and hope for the best, let it distill itself
of what ive understood nitritification is less problematic than nitration
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woelen
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|I did the nitrite ester formation reaction with several different alcohols (methanol, iso-propanol, n-propanol, n-butanol). In all cases, the
reaction proceeds fast and without any hassle. I use cold (not ice cold, just cold) solutions. I mix the alcohol with some dilute acid and to this I
slowly add a cold solution of NaNO2. With CH3OH this leads to vigorous bubbling (escape of the gaseous CH3ONO, which easily burns with a grey flame),
with the other alcohols I get a yellow layer on top of the aqueous layer. It easily can be pipetted from the aqueous layer and neutralized with
NaHCO3. Never had any issues with this reaction. I use commercial grade NaNO2.
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