Natures Natrium
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Reaction of alkyl nitrite/chloride and sodium hydroxide
I am currently trying to work up and separate the products resulting from a 4 hour reflux of isopropyl nitrite, isopropyl alcohol, and sodium
hydroxide.
0.4 mol of sodium hydroxide
Source: drain cleaner, no additives, used directly
200 mL of Isopropanol
Source: Rubbing alcohol, salted out, separated and distilled
0.4 mol of Isopropyl nitrite
Source: Reaction of meat curing salt (6.25% NaNO2) and single distilled 20% HCl(aq), however due to a miscalculation and a deviation from
planned reaction, I didn't have enough HCl, so I finished with a slight excess of H2SO4. I realized only afterwards that this probably created
favorable conditions for the chlorination of the secondary alcohol.
After addition of sodium hydroxide to the isopropanol, a secondary layer was formed that likely represented the remaining water fraction of the
solution. After allowing the hydroxide to dissolve as much as possible and the overall solution to cool to room temperature, the distilled isopropyl
nitrite (which I now suspect contained an unknown amount of chloride) was added to the rbf flask.
The solution was refluxed for 4 hours, during which time the color changed from a light yellow to a deep red. In particular the water layer was much
darker than the isopropanol layer.
After reflux the alcohol was distilled off, the first 50mL being a very light yellow in color and having just a vague scent of isopropyl nitrite.
Most of this was isopropanol according to the distillation temp. The next 100 mL was clear, and smelled of "dirty" isopropanol.
The resulting water solution (still deep red) was allowed to cool and a good deal of salts crystallized out, enough to freeze the stir bar.
A bit of these salts were scraped up with a spatula, and placed in a beaker with a few drops of sulfuric acid. The salts immediately reacted by
dissolving and effervescing, however the gas being emitted was was not colored brown by contact with air. It did appear to be a heavy than air gas,
and remained at the bottom of the beaker. An accidental smell seemed to indicate oxides of nitrogen. The clear sulfuric acid (battery grade) turned
a very light yellow color.
Are oxides of nitrogen particularly soluble in sulfuric acid? Does sodium hyponitrite effervesce on contact with sulfuric acid?
100mL of distilled water was added, which formed a lighter red, pH neutral solution. This is being heated to drive off 1/3 to 1/2 the water, then
will be chilled and the crystals filtered in an effort to seperate the salt from the red solution.
Just not sure what I have yet, if I can get it recrystallized I can try to take a melting point, or even decompose it under dry heat to help identify
it. If anyone has any comments or suggestions, by all means, please do so.
As an aside, the salt formed here strikes me a bit like the salt that I formed many years ago, from capturing the off gasses of a psuedonitrosite
formation in a column of strong sodium hydroxide solution. That solution was put in the back of a cabinet and slowly evaporated over many months to
yield very thick, hard, and clear crystals of a substance that also effervesced on addition to strong mineral acid, but did not appear to create any
NO2.
[Edited on 14-11-2012 by Natures Natrium]
\"The man who does not read good books has no advantage over the man who cannot read them.\" - Mark Twain (1835-1910)
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Natures Natrium
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Registered: 22-12-2004
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Update:
The switching heating element controller on my hotplate died.
The solution became hot, but not enough to boil or evaporate appreciably, then cooled after the element stopped functioning.
Interestingly enough, it diverged into two phases, the lighter one being a slightly off tan, translucent, oily liquid. The heavy phase continued to
be red but more trending toward brown, and seems like it is the water phase due to volume and viscosity. They were separated via funnel and placed
into rubber stoppered erlenmeyer.
Upon cooling both in a standard freezer, neither phase precipitated solids or crystallized.
I suppose I can check boiling points on these if/when I get my hotplate fixed. I have a non-stirring plate, but I am spoiled and prefer the
relatively hands free operation of the stirring plate.
\"The man who does not read good books has no advantage over the man who cannot read them.\" - Mark Twain (1835-1910)
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Natures Natrium
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Posts: 163
Registered: 22-12-2004
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Sorry for the triple post. Decided I would share this anyways.
Hotplate is semi-working, top half of dial is working.
Boiled off 2/3 the volume of the clear solution, B.P. of liquid was ~80C and it smelled heavily of isopropyl alcohol. What is left is a thick,
slightly yellow liquid. No salt crystallized out.
Boiled off 1/2 of red solution, temperature of boiling liquid was 109C rising to 125C with heavy foaming towards end. After removing from heat,
crystals of a salt began to form immediately. This was allowed to cool to room temperature. It formed a thick suspension of salt in viscous
brown-red goop. 50mL of distilled methanol was added to effect solvation of the goop and further "crashing out" of the salt crystals.
Instead, while the methanol and red goop did solvate, the solution became rather warm to the touch, and began to very lightly effervesce.
At this point I am not much inclined to pursue it further, as my desire was the simple isolation and purification of nitrite salts from meat curing
mixtures. I lack the skill and equipment to identify what compounds are present.
Has anyone here ever tried to form an alkali nitrite from an alkyl nitrite by refluxing with an alkali hydroxide? If so, I would very much like to
hear about your experiences with the reaction.
\"The man who does not read good books has no advantage over the man who cannot read them.\" - Mark Twain (1835-1910)
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