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Lionel Spanner
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Quote: Originally posted by BAV Chem  | On another note, what is the calcium hydroxide even there for in this reaction?
Some include it while others leave it out completely. I had some success with starch and no hydroxide and got a 30% yield (see a few posts above).
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It's so the reaction takes place in alkaline conditions, and produces an insoluble carbonate that can easily be separated from the nitrite. I should
think you'd get very different reaction products in neutral or acidic conditions.
[Edited on 18-3-2022 by Lionel Spanner]
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BAV Chem
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It makes sense to run the reaction under alkaline conditions but doesn't that happen on its own without any hydroxide.
At the temperatures the reaction happens at some nitrite is inevitably gonna decompose to sodium oxide which ends up as sodium carbonate.
The calcium hydroxide will obviously deal with the carbonate but then you have NaOH instead of carbonate, which isn't much better. Also it'll turn
into carbonate anyways upon standing.
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Fantasma4500
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im gonna try the starch method asap. however it seems quite dark on my end as i have just tried using pure NaNO2, cold water and HCl with some IPA-
the reaction quickly gets very hot and 2 layers seperate very quickly- quite contrary to anything ive achieved so far
i believe i also did flour, KNO3 and Ca(OH)2 - as well as without calcium hydroxide and got around same results, if not infact a bit worse
as for what im seeing, 30% yield seems incredibly optimistic. now i typically do use potassium nitrate, which is stable at much higher temperature
(300*C higher?) and for now i can only pick between sodium sulfate contaminated NaNO3 or god forbid- sodium chlorate contaminated sodium nitrate. the
latter can cause a spike in adrenaline. if sodium hydroxide and glucose is used, even in small amounts- didnt bother more with that yet.
as my results are not very interesting so far ill share what ive gone through
CaSO3 (well contaminated with Ca(OH)2 ) - seemed to do nothing at all
calcium sulfamate - total negative
steel wool- great potential
flour and hydroxide- great potential
lead- it should work but not having much success
ascorbic acid, reacted in solution - dont bother- very violent if mixed dry but does also work to some extent- maybe stoichiometry will make this
work, or downing reaction speed with gypsum or similar.. sand?
MgAl- powder/chunks- some potential, mixture may with even very large pieces in closed atmosphere turn into a gigantic flare
sodium dithionate- total negative (solution)
iron oxalate- does work but not impressive yield
to be tried out: NaOH + NO2
NO2 from HNO3+ Cu, ascorbic can also work but will probably eat up a bunch of the formed NO2
it reacts accordingly: NaOH + NO2 = NaNO2 + NaNO3
oswald reactor leading into NaOH or even better KOH would work well, reference KNO2/KNO3 solubilities
as for crashing out KNO3, having a somewhat concentrated solution and added maybe 10-20% IPA (or ethanol) and then putting it in freezer should crash
out mostly the nitrate
yet to try is Cr2O3 fused with KNO3, yielding K2CrO4 and KNO2
as for thermal decomposition- KNO3 is much more resistant to heat, i did in the past have some luck decomposing NaNO3 on hotplate (700*C hot)- ive
tried this again with a new hotplate that only reaches 500*C and its just barely a slight positive for nitrite. ideally the sodium nitrite has to
reach up to 800*C to efficiently decompose into sodium nitrite
purification of the nitrite can be done by converting it into IPN, distilling it off and reacting with a strong base, to create IPA and corresponding
nitrite salt
cobalt and potassium combines with nitrite ions, or rather HNO2 to form a well insoluble complex called potassium cobolt hexanitrite. it does eat up
some nitrite in the formation, and the complex appears very stable towards acids- so reaction with base is one of few ways ive found viable to make
the nitrite useful in it- i didnt try concentrated sulfuric acid on it.
otherwise to have the crude portion precipitated out as KNO2/KNO3 in freezer with some alcohol added would remove most of the nitrate. KNO3 is
16g/100mL at 0*C in water, lower temperature aswell as alcoholic solution will further down the solubility while KNO2 is soluble at 200+g/100mL
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clearly_not_atara
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After some further consideration, it seems like the goal is a less energetic reducing agent. Perhaps a formate salt would be ideal:
2 KNO3 + 2 KHCO2 >> K2CO3 + 2 KNO2 + CO2 + H2O (g)
Or maybe even oxalate (if it reacts):
KNO3 + Na2C2O4 >> KNO2 + Na2CO3 + CO2
A sodium-potassium nitrate eutectic might be useful, but potassium formate already melts at 165 C with decomposition from 280-335 C:
https://pubs.acs.org/doi/pdf/10.1021/es60044a002
[Edited on 18-3-2022 by clearly_not_atara]
[Edited on 04-20-1969 by clearly_not_atara]
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Lionel Spanner
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| Quote: Originally posted by S.C. Wack | Nitrite can be determined quantitatively by titration of a solution with permanganate in warm dilute sulfuric acid: 2KMnO4 + 5KNO2 + 3H2SO4 ->
5KNO3 + 3H2O + 2MnSO4 + K2SO4
[Edited on 17-3-2022 by S.C. Wack] |
Another way is titration with ceric sulphate with ferroin as an indicator. This is advantageous if, like me, you don't have the patience for
permanganate titrations.
(At my last job, I often carried out permanganate titrations to determine hydrogen peroxide content of peroxide cream, and it'd get painfully slow
towards the end point; a single titration would typically take around 30-40 minutes.)
[Edited on 18-3-2022 by Lionel Spanner]
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Keras
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| Quote: Originally posted by Keras | Still, I’m surprised that the sodium dithionite method doesn’t work. If I follow the CRC Handbook, we have:
NO₃⁻ + H₂O + 2 e⁻ ⇋ NO₂⁻ + 2 OH⁻ e = 0.01 V
2 SO₃⁻ + 2 H₂O + 2 e⁻ ⇋ S₂O₄²⁻ + 4 OH⁻ e = -1.12 V
So logically, this reaction:
NO₃⁻ + 2 OH⁻ + S₂O₄²⁻ → NO₂⁻ + 2 SO₃⁻
should have e = 1.13 V, which is a pretty high K and should be almost quantitative, no?
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Darn, that was totally wrong 
Should be:
NO₃⁻ + S₂O₄²⁻ + 2 OH⁻ → NO₂⁻ + 2 SO₃²⁻ + H₂O
In any case, it doesn’t seem to work. I tried to heat the solution, and still no luck; so the problem is not kinetic. Why this does not work is
beyond me.
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clearly_not_atara
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The ions electrostatically repel; there is no mechanism to bring them together. Kinetically, decomposition of dithionite is probably faster than rxn
with nitrate under any realistic conditions. Maybe you could reduce an alkyl nitrate with dithionite, but that's a poor choice safety-wise.
[Edited on 04-20-1969 by clearly_not_atara]
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Fantasma4500
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@clearly_not_atara
KNO3/NaNO3 mix have been used as a thermally stable salt mix for solar panels or something relating to solar panels
avoid KNO3.
ive had great success using lead, finally. but it requires sodium nitrate
you get about 200g Pb3O4 per 80g of nitrite, so you will need a bunch of lead if you wanna try it or utilize it
i havent looked much into turning Pb3O4 into Pb, which would be very handy..
procedure was as simply as just dump NaNO3 and Pb into a crucible, put on hotplate and cover with insulated pot, Al2O3 wool secured through a hole
with a bolt+washer. my hotplate gets to 500*C which is plenty fine, you wanna stir the mixture up a few times as the reaction happens at the surface
of the lead and Pb3O4 forms
it seems quite effective, best to do is to pour the molten content from crucible out into a metal tray, discard most of the lead for further use and
then dissolve it in hot water, filter it and then turn it into IPN right away
then you suck out the IPN and store in bulk, distill it at 40*C and hydrolyze with NaOH to get- practically pure NaNO2
as it appears KNO3 + Pb doesnt work, i would steer clear of fractionally crystallizing nitrate/nitrite
if one was to construct oswald device and pump the NOx into KOH, one would get KNO3/KNO2 mix, which then can be fractionally crystallized, 60g is
doable a day in industrial setup, maybe 30g with a really great homebuilt setup- loose number ive gotten from setups found on youtube with vague
explanations of yield
NO would react with NaOH to form NaNO2- but forming NO doesnt as i see it seem viable, if NOx could be turned into NO that would make for very great
yields with oswald
in any case, making nitrite it appears that you wanna avoid using potassium nitrate as starting material as its quite stable compared to sodium
nitrate. i did also do 100g KNO3 + 50g Ca(OH)2 + 32g flour and it had some yields but not super impressive, i highly doubt it was as high as 30%
yield, but it does appear to increase yields when you scale it up
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clearly_not_atara
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Nitrate salt eutectics are used as heat storage fluids with a wide liquid range and low corrosive potential in solar thermal installations to allow
dispatchable electricity generation; could this be what you mean?
Nitrate salt decomposition is not exothermic in the absence of acids (incl. CO2) so as long as these salts are sealed they work great. In fact:
2 Na2O + 2 N2 + 5 O2 >> 4 NaNO3
is "exothermic" but kinetically impossible (for all we know).
[Edited on 04-20-1969 by clearly_not_atara]
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Keras
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| Quote: Originally posted by clearly_not_atara | | The ions electrostatically repel; there is no mechanism to bring them together. Kinetically, decomposition of dithionite is probably faster than rxn
with nitrate under any realistic conditions. Maybe you could reduce an alkyl nitrate with dithionite, but that's a poor choice safety-wise.
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Of course, you’re right. I’m dumb.
By the way, I just tested sodium dithionite with ferrous chloride, and that gave me iron powder, which immediately oxidised when exposed to air.
[Edited on 21-3-2022 by Keras]
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Keras
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Is there any reason why zinc or iron could not reduced nitrates?
Since NO₃⁻ + H₂O + 2 e⁻ ⇋ NO₂⁻ + 2 OH⁻ e = 0.01 V, every metal that HCl oxidised should be able to reduce nitrates to nitrites, no?
Like: NO₃⁻ + Zn + H₂O → Zn(OH)₂ + NO₂⁻
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Keras
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Update: I did that. I just dropped a screw made of zinc plated steel into a solution of a few hundredths of milligrams of KNO₃.
Heated it up a bit, let it evaporate at r.t.
Got some beautiful transparent, needle like crystals. Does that correspond to potassium nitrate?
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Fantasma4500
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@keras please read the other posts in this thread
interesting with dithionite and iron, this in solution could maybe work for nitrite- it could maybe work to produce zinc powder? i have a bit of it
that stuff- honestly i feel done with experimenting with producing nitrites, i have found working methods by now
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Fantasma4500
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NOCl + NaOH = NaNO2 + NaCl + H2O
HCl + KNO3 would form NOCl? this is much like NO2 + NaOH except- this one may be more selective as all the nitrogen compounds goes to NaNO2 where for
instance NO2 + NaOH turns into i believe 1:1 nitrate/nitrite
https://pubs.acs.org/doi/abs/10.1021/jp972143m
i did also find other - seemingly automated saying:
NOCl + NaOH = NaNO3 + NO + NaCl + H2O
NaOH + NOCl = NaCl + HNO2
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clearly_not_atara
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I think it could work, but it's my understanding that the offgas from aqua regia is a lot more complicated than just NOCl. There's also some NO2, NO,
and Cl2 in there.
Also, the variation I had heard most often was sending just nitric oxide -- NO without NO2 -- through NaOH, which apparently still gives nitrite (and
nitrous? or something?). But I'm not sure how to generate this reliably in a controlled fashion -- the dilution of your HNO3 will change as it reacts,
if you use metal reduction, so obtaining a steady stream of NO is non-obvious.
[Edited on 04-20-1969 by clearly_not_atara]
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Fantasma4500
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i did a run where i used 100ish mL of HNO3 and maybe 15g copper, boiled down the solution a bit before reacting it with IPA + HCl, acquired about 25mL
IPN - a slight bit tainted with IPA, it appears the IPA can both be in the water phase but also gets pulled out into the IPN
the IPN formed quickly pulls the IPA out of solution and seperates
i need to scale this up with proper dripping mechanism
i have 1 reaction flask with HNO3 being dripped into it, 1 airpump going in to force the gasses through (and eventually clean apparatus, and avoid
suckback)
and then distillation bridge going to next flask to collect water, HNO3 and avoid suckback, then hose attachment comes out of this to bubble into NaOH
biggest challenge in this whole thing is keeping apparatus cold, getting the nitric acid and also having a working setup- dripping funnel, this can
maybe be discarded by using lower conc HNO3 and dumping copper in like that
you get your second crop of NO2 by decomposing Cu(NO3)2 at 220*C, this gives same amount of NO2 as the nitric acid reaction does
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clearly_not_atara
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How are you differentiating isopropyl nitrite from isopropyl nitrate?
[Edited on 04-20-1969 by clearly_not_atara]
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BAV Chem
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| Quote: Originally posted by Antiswat | i did a run where i used 100ish mL of HNO3 and maybe 15g copper, boiled down the solution a bit before reacting it with IPA + HCl, acquired about 25mL
IPN - a slight bit tainted with IPA, it appears the IPA can both be in the water phase but also gets pulled out into the IPN
the IPN formed quickly pulls the IPA out of solution and seperates
i need to scale this up with proper dripping mechanism
i have 1 reaction flask with HNO3 being dripped into it, 1 airpump going in to force the gasses through (and eventually clean apparatus, and avoid
suckback)
and then distillation bridge going to next flask to collect water, HNO3 and avoid suckback, then hose attachment comes out of this to bubble into NaOH
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Hey Antiswat, I can't quite follow this procedure here. I would think you added IPA and HCl to a solution of Cu(NO3)2 ...which
produced isopropyl nitrite? Now that seems like it wouldn't work.
Or did you just react IPA, HCl, HNO3 and Cu directly to afford a whole slew of reactions which end up producing isopropyl nitrite amongst
other things.
Either way this brings me to another idea which might just work to make nice and pure alkali nitrite.
I'm thinking if you react nitric acid with a large excess of EtOH you'll get a whole bunch of interesting reaction products: NOx gasses,
HNO2, Acetaldehyde, Acetic acid, CO2... and eventually Ethyl nitrite. The latter is a gas and could easily be bubbled through an
ethanolic solution of NaOH or KOH, affording the corresponding alkali nitrite which precipitates out.
I've already done some test with ethanol and nitric acid. If a large excess of EtOH is used the resulting gas is colorless and certainly smells like
Ethyl nitrite. It also burns with the characteristic white flame of nitrite esters.
Quite possibly one could even substitute nitric acid for a nitrate salt and a mineral acid.
What do you think about this approach?
[Edited on 20-6-2022 by BAV Chem]
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Fantasma4500
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the procedure was reacting Cu with HNO3 to form Cu(NO3)2 and NOx, was was pumped into NaOH to yield NaNO3/NaNO2- this solution was reduced and then
reacted with IPA/HCl to form IPN
i have thought of directly pumping it into IPN but it might give other compounds as well that you then have to deal with seperating, volatile ones,
potentially explosive.
HNO3 and EtOH? interesting. ascorbic acid also works despite the ascorbic acid reacts with the NOx
https://en.wikipedia.org/wiki/Calcium_nitrite
this would explain that NOx + hydroxide is indeed a quite viable method. burning dry ammonia is also an idea, but thats a more complicated apparatus,
imo. oh i might also stress... ethyl nitrate may derive from HNO3+ EtOH. methyl nitrate is a high-explosive with decent sensitivity. thiscould be a
dangerous reaction.
upon reading your writings on Etnitrite- thats very interesting... Etnitrite is like 13*C boiling point or something iirc, i would try this with IPA
where the resulting nitrite is boiling at about- hm 40*C? this is much easier to handle, less volatile, you will need to react this chemical with NaOH
to once again produce the desired nitrite salt.
NaHSO4 + nitrate could do yeah, though i think activating the NaHSO4 takes some heat- you might have to distill on it seperately first, thus arriving
at HNO3
cant platinum or something catalyse the decomposition of nitric acid? there has got to be some more simple way to this
i would indeed say the nitrite flame is quite likely .... buuut that could also be the same with nitrate? so acquire an amount of this material and
test boiling point maybe, i usually just put digital thermometer into a testtube and carefully heat it
maybe we should look further into the decomposition of HNO3? as i mentioned, Cu(NO3)2 - which can be made by Ca(NO3)2 + CuSO4 decomposes at 220*C to
yield decent amounts of NO2 as it turns into CuO. if some NO forms thats actually much better than NO2, maybe we wanna also look into turning NO2 into
NO? my last searches on this yielded not much
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Hexabromobenzene
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Sodium nitrite is a byproduct of the production of nitric acid from the air. Absorbing gases after water by sodium carbonate solution you will have
pure nitrite with almost no nitrate
To get pure nitrite, you need an equivalent mixture of NO and NO2.
If you do not want to get nitric acid from the air, then you can get nitrite directly from the air. Reduce the maximum volume of the oxidation chamber
for nitrous gases
You will need a transformer from neon lamps for 7-15 kilovolts.
You can easily have a nitric acid output of up to 10 grams per kilowatt hour or more.
Nitric acid and sodium nitrite can be free if you find a wire with 220 volts without an electric meter))
[Edited on 23-6-2022 by Hexabromobenzene]
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clearly_not_atara
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So what you're saying is, if you feed NOx through neutral water first, and the unabsorbed gases through alkali, the second flask will contain almost
exclusively nitrite?
It makes sense, since the secondary flow should be mostly NO with little NO2. It may be relevant in this context that iron (III) nitrate releases
practically all of its NOx at just over 150 C:
https://link.springer.com/content/pdf/10.1023/A:101011281401...
[Edited on 23-6-2022 by clearly_not_atara]
[Edited on 04-20-1969 by clearly_not_atara]
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Fantasma4500
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it appears that youre right, about 150*C its effectively turning into NOx
https://tkuir.lib.tku.edu.tw/dspace/retrieve/82495/-JMR-JMR5...
im not sure if im reading this right though, it seems quite vague, they dont mention really what the weight is thats being lost- nothing about nitrous
gasses? as for copper vs iron i would further argue that the decomposed copper nitrate can be recycled with nitric acid, while Fe2O3 might be more
difficult to do like this, obviously iron nitrate has a lot of waterweight to it and they mention as much as 1300*C
i think i did come around the actual relevant decomposition temperature of iron nitrate last time i looked into the nitrate salt decompositions for
NOx
the NO2 scrubbing with water is very interesting, but simply dump it into KOH solution, chill this well and you will have quite concentrated KNO2
solution- and then you can very easily turn this into nitrite of whatever sort, maybe ethyl nitrite directly used for isomeric re-jumbling into
nitroalkyl, whatever the correct term be.
ANOTHER trick i was hinted by a fellow chemist in this would be to add some H2SO4 to the copper before adding nitric acid
this will react with the Cu(NO3)2 formed- making more HNO3, which then goes on to react once again
this would be very interesting to try with iron. drip HNO3 onto that while its already got H2SO4, the iron never becomes iron nitrate
the NO2 water scrubbing method seems rather silly to me because largely NO2 is produced- however if you recycle the freshly formed HNO3- albeit very
dilute it can start to make sense, but you'd be running some serious bulk to make it work, KOH would be best bet at seperating out large amounts very
fast.
forming NO2/NO out of air and pumping into KOH would be a better method than using precious HNO3, it may produce about 30 grammes a day with a small
setup, that being maybe 15g of nitrite? in a month thats 450g.
we still have yet to test out how NOCl + NaOH does. if the nitrogen in that works entirely like NO would in NaOH that would mean very great yields,
and one could just fractionally crystallize the sodium nitrite and HCl / nitrate salt may be possible for generating the gas
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Fantasma4500
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im thinking of utilizing ethyl nitrite, as this can be isomerized into nitro by passing it through a tube thats heated to 130*C packed with mineral
wool
if the temperature is kept at near BP of EtOH- ethyl nitrate should decompose? its a potentially dangerous procedure, i was thinking of just dropping
nitric acid into EtOH/copper metal and using ethyl nitrite directly
but ethyl nitrate is quite dangerous if it doesnt decompose.
https://en.wikipedia.org/wiki/Ethyl_nitrate
here they explain 10% HNO3 in EtOH is potentially explosive... because of vapors? and ethyl nitrate is commonly made by nitration of ethanol - but
methyl nitrate is made by distilling HNO3 with MeOH
we need something on how to completely eliminate EtNO3 because just a single drop of this that goes off could wreck glassware and even your life
https://en.wikipedia.org/wiki/Nital#:~:text=A%20solution%20o...
https://patents.google.com/patent/CN102531909B/en
"The invention discloses a method for preparing ethyl nitrate by continuously nitrifying nitric acid steam, which belongs to the field of energetic
materials ..."
they mention adding urea and trimeric cyanamide, its a bit confusing to read since its translated from chinese. they mention adding the ethanol
directly to this nitric acid mixture which is.. 75% or 68%? at a temperature of 60*C
distillation at 90*C where the ethyl nitrate is left in the reaction vessel, which it can then be washed with simply water
"be warming up to 90 ℃ and start to reflux 5 minutes; Reflux, just steam product on one side, 90 ℃ of crude product upper stratas that obtain of
distillation temperature are unreacted ethanol, and lower floor is thick ester and acid,"
this would be safer if you have excess EtOH and heat that to BP of ethanol?
99% EtOH reacts with 70% HNO3 within a minute at STP while 95% can take an hour of incubation time, where it in both cases vigorously boils up- likely
ethyl nitrite. hydroxylamine is also mentioned. possibly ethyl nitrate carefully decomposing into nitrogenous gasses
now, nitroethane however, is also somewhat insoluble in water- i believe its 4g/100mL, but it floats ontop of water, while ethyl nitrate- assuming the
two wouldnt end up dissolving in one another, would sink to the bottom
this would potentially make this reaction feasible
https://www.toppr.com/ask/question/when-ethyl-alcohol-reacts...
"When ethyl alcohol reacts with nitric acid, it forms: · Nitromethane · Nitroethane · Ethyl nitrate · Diethyl ether · Chemical Properties of
Alcohols and Phenols - ...
Top answer:
Correct option is C) Ethyl nitrate"
no mentions on reaction conditions.
keeping the HNO3/EtOH mixture from suddenly increasing in temperature would be how to keep ethyl nitrate away, i believe
and this could maybe be done by reacting the HNO3 directly with Cu to form NO/NO2, which with methanol can in vaporphase directly form nitromethane
and this would also ensure no runoff if the nitric acid can react right away with the copper.. in excess EtOH maybe? unfortunately EtOH is miscible
with practically all solvents, but the ethyl nitrite should come off if its just kept at 30*C, or room temperature even
[Edited on 9-7-2022 by Antiswat]
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Pumukli
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I would avoid ethyl-nitrite/nitrate altogether and would try to do something (optimize?) the HNO3/starch method.
E. Divers in 1899 (or so) wrote that this is the way to go if you want to make good quality NaNO2 with very low NaNO3 contamination.
The trick is he "forgot" to mention the right concentration of HNO3 and the right temperature of the reaction! :-) Only wrote about those that "you
should adjust them in order to produce NO/NO2 mix where NO is in a slight excess". This is the key. This is what the optimization should aim for!
He only wrote that the gas mix should be absorbed into NaOH (or Na2CO3) solution, AND the excess, unabsorbed gas should be only NO! So it should be
COLOURLESS what "bubbles away" from the absorbent solution!
Basically one should make a NOX generator which makes slightly more NO than NO2. I would rather "play" with this generator and determine the optimal
working parameters of it than risk to work with EtONO/EtONO2. But for each of his own. ;-)
[Edited on 13-7-2022 by Pumukli]
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Texium
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Thread Topped
13-7-2022 at 08:34 |
Texium
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Threads Merged
13-7-2022 at 08:38 |
Texium
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It looks like this thread has been the main place for nitrite synthesis-related discussion for the last five years, so I've merged it with the
original nitrite thread and stickied the resulting big thread for better visibility.
As it seems like sodium nitrite is becoming less available OTC in some areas, having a sticky thread on unconventional preparations seems warranted.
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