Ioxoi
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Aldol Reaction of Acetone and Nitrous Acid
Hello all,
This is probably more of an organic question, but it is somewhat mundane so I placed it here. I have done a reaction and, lacking access to an NMR at
the moment, I have no idea of what I have made. Here is what I did:
About 2mL acetone was placed in a glass vial.
About 1/4 mL isopropyl nitrite (as an indirect form of nitrous acid) was added.
Nothing happened, as predicted.
A drop of 30% HCl was added and swirled. This produced a strong orange coloration.
The temperature remained the same for a while, and then it slowly began to warm, and soon became so hot it was somewhat painful to hold the vial.
After a while the orange coloration disappeared.
A few more drops isopropyl nitrite were added slowly, with heat generated.
Some NaHCO3 was added, creating a small amount of bubbling.
The liquid portion was dried, producing a mass of needlelike crystals with a sweet odor.
I believe the reaction was an aldol-like reaction, where acetone enol attacks from alpha carbons on NO+ ion generated in situ.
A similar reaction between ethyl nitrite and methyl ethyl ketone is found here on Org Syn:
http://orgsynth.org/orgsyn/orgsyn/prepContent.asp?prep=cv2p0...
In their reaction, the product is the methyl ethyl ketone with an oxime attached to the alpha carbon. I would thus predict my plate of crystals is
CH3 - C=O -CH=NOH
i.e. the monoxime of Methylglyoxal:
http://en.wikipedia.org/wiki/Methylglyoxal
Since the oxime is at an aldehyde position, I would expect it to be quite vulnerable to being attacked. So if I let it sit in water I'd probably get
methylglyoxal and hydroxylamine.
Might there also be a small amount of double aldol product as well? ie HON=CH-CO-CH=NOH
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DJF90
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You may also have other acetone condensation products in there, such as mesityl oxide, supposedly with a peppermint odour. But I also susepect you
have formed the oxime(s) also.
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woelen
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The transient orange color could very well be from nitrosyl chloride, formed from the nitrite and the acid. Just for fun, try adding some NaNO2 to
conc. HCl and then you'll probably observe exactly the same orange color. With organic nitrites I also can imagine that in some way first HNO2 is
formed, which reacts with conc. HCl, giving ONCl and H2O.
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Nicodem
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This is not an aldol reaction. An aldol reaction is an electrophilic substitution at the alpha-position of a ketone/aldehyde with a nonenolizable aldehyde as
electrophile. In alpha-nitrosations of ketones, the electrophile is a nitrite ester, HNO2 or other electrophilic nitrosation reagents. The mechanism
is related, though via acid catalysed enolization (base catalysed nitrosations also exist), but so is also in the alpha-halogenations, acylations, the
Mannich reaction and many other reactions of ketones at the alpha position.
There is no need to call for any NO+ species to explain the mechanism. Nitrite esters and HNO2 are electrophilic at the nitrogen atom already as such
(and obviously there are no "alpha carbons on NO+ ion"). Other example of ketone alpha-nitrosation at Org. Synth. include:
http://orgsynth.org/orgsyn/orgsyn/prepcontent.asp?print=1&am...
http://orgsynth.org/orgsyn/orgsyn/prepcontent.asp?print=1&am... (with rearrangement)
In the literature you can find numerous other examples.
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papaya
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"Might there also be a small amount of double aldol product as well? ie HON=CH-CO-CH=NOH " - I want to raise this question again - what are the
expected products of the reaction of acetone and sodium nitrite in acidic aqua solution? If diisonitrosoacetone (wrong name?) can be synthesized this
way - how to separate it? Thanks.
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Boffis
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I don't know if this helps but some years ago while investigating metal complexes of 1,2 dioximes I tried to prepare some asymmetric dioximes by the
published route to dimethylglyoxime via butanone and butyl nitrite. I tried it with acetophenone, butyl nitrite and HCl gas and got an orange waxy
product. When I attempted to purify it I recovered almost half of the acetophenone but all of the nitrite seemed to have been consumed. I couldn't
identify the orange product but the colour suggests a nitroso compound, I don't have a melting point value to hand but the melting point was fairly
low <100 C.
It would appear from the amount of unreacted acetophenone that it reacts with 2 molecules of nitrite instead of the desired one. I came across a
base-catalysed condensation of alkyl nitrite with 2 nitrotoluene to give the oxime of 2 nitrobenzaldehyde so I might try this reaction with
acetophenone sometime bur according to the references I have it is a very difficult reaction to control (very exothermic).
I would postulate that acetone would react similarly.
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papaya
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Why they use organic nitrite in such reactions, what about NaNO2 + acetone + acid ?
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Boffis
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@papaya; because if you are trying to isolate the nitroso/isonitroso/oxime a non-aqueous environment reduces hydrolysis. An aqueous environment also
limits the strength of acid or base you can use affecting the reactive species. Have you tried nitrosating any organic compound with aqueous nitrous
acid, specifically acetone?
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papaya
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No, I didn't, this is why I'm asking. If there's an easy way to dinitrosoacetone I may try to make it since I suppose it is able to give an insoluble
complex with nickel like dimethylglyoxime (the latter requires sodium hydroxylamine monosulfonate in synthesis which is inaccessible). Btw. IF it
gives insoluble complex with nickel 2+ then this is way to isolate it, right?
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Boffis
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@papaya, there is a whole thread on di-isonitrosoacetone, check out;
http://www.sciencemadness.org/talk/viewthread.php?tid=2969
I have looked at the route from citric acid but judging from Axt's experiments described in that thread you do need fuming sulphuric acid to get a
good yield and this is hard to get. Its interesting to note that in one of the published preparations of the intermediate acetone-dicarboxylic acid it
states that it doesn't matter whether you use anhydrous citric acid or the monohydrate (most common citric acid it the monohydrate) with your fuming
sulphuric acid. Axt doesn't say whether he used the monohydrate ore not but if you are using conc sulphuric acid (98%) it may be better to dry the
citric acid first. Sorry this is a bit off topic.
By the way you don't need Na hydroxylamine sulphonate to prepare dioximes from the mono-oxime. Any hydroxylamine salt will do. Axt has described the
preparation of the hydrochloride in his thread on diaminofurazans (check out pre-publication) and Bauer in the SM library carries a synthesis of the
sulphate which is very do-able.
Yes you can isolate many of the compounds by their Ni salt and the treat with ice-cold HCl or possibly H2S. I have had mixed results with hydrochloric
acid, sometimes the yield is very low and I suspect that there is significant hydrolysis of the oxime by the acid though avoiding an excess acid may
be the key here.
I might investigate the orange products again; it appears that only compounds with an active methylene groups undergo the nitrite condensation to give
an oxime (=isonitroso) group, compound that only posses a methyl group adjacent to the carbonyl seem to under go a different reaction. The methylene
group doesn't have to be adjacent to a carbonyl group some nitriles react similarly eg malononitrile gives an oxime with aqueous nitrite and acid and
in an old paper I am currently translating there is a reference to a similar reaction being given by cyanoacetic acid.
If you try aqueous nitrous acid on acetone etc please report your results. By the way it might be worth trying acetylacetone as it has an active
methylene group. I have references to many of these reactions so I'll try and dig them out and post them.
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Random
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It is a known route to isonitrosoacetone which by Fe/HCl reduction yields a compound that can be oxidized to 2,5-dimethylpyrazine.
I have posted multiple times on this forum this reaction but lacked nitrite to actually perform it.
[Edited on 26-9-2013 by Random]
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papaya
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Quote: Originally posted by Boffis  | @papaya, there is a whole thread on di-isonitrosoacetone, check out;
http://www.sciencemadness.org/talk/viewthread.php?tid=2969
I have looked at the route from citric acid but judging from Axt's experiments described in that thread you do need fuming sulphuric acid to get a
good yield and this is hard to get. Its interesting to note that in one of the published preparations of the intermediate acetone-dicarboxylic acid it
states that it doesn't matter whether you use anhydrous citric acid or the monohydrate (most common citric acid it the monohydrate) with your fuming
sulphuric acid. Axt doesn't say whether he used the monohydrate ore not but if you are using conc sulphuric acid (98%) it may be better to dry the
citric acid first. Sorry this is a bit off topic.
By the way you don't need Na hydroxylamine sulphonate to prepare dioximes from the mono-oxime. Any hydroxylamine salt will do. Axt has described the
preparation of the hydrochloride in his thread on diaminofurazans (check out pre-publication) and Bauer in the SM library carries a synthesis of the
sulphate which is very do-able.
Yes you can isolate many of the compounds by their Ni salt and the treat with ice-cold HCl or possibly H2S. I have had mixed results with hydrochloric
acid, sometimes the yield is very low and I suspect that there is significant hydrolysis of the oxime by the acid though avoiding an excess acid may
be the key here.
I might investigate the orange products again; it appears that only compounds with an active methylene groups undergo the nitrite condensation to give
an oxime (=isonitroso) group, compound that only posses a methyl group adjacent to the carbonyl seem to under go a different reaction. The methylene
group doesn't have to be adjacent to a carbonyl group some nitriles react similarly eg malononitrile gives an oxime with aqueous nitrite and acid and
in an old paper I am currently translating there is a reference to a similar reaction being given by cyanoacetic acid.
If you try aqueous nitrous acid on acetone etc please report your results. By the way it might be worth trying acetylacetone as it has an active
methylene group. I have references to many of these reactions so I'll try and dig them out and post them. |
Well I tried to mix diluted HCL/acetone + NaNO2 water solutions slowly, however I noticed nothing to precipitate on standing - it just bubbles slowly,
also addition of NiCl2 didn't give any precipitate. I don't know if anything interesting formed and still stays in the solution - most probably not.
Is this reaction really require anhydrous conditions (what will happen to the oxime in water)?
And yes - I saw that thread, but I don't have any hydroxylamine salts, and have a question: he makes acetone dicarboxylic acid, then reacting with
nitrite gives dioxime(is COOH replaced by =N-OH or alfa methylene hydrogens condense with nitrous acid and then it decarboxylates?) then they want to
introduce the third N-OH with hydroxylamine - why just not react citric acid with nitrite and put 3 groups at once? or I don't understand something
very important (that's the case - I don't understand much of organic chemistry).
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AndersHoveland
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I am not sure if this will help, but I have some references to acetone being oxidized by mixtures of nitric acid and nitrogen dioxide:
| Quote: |
"US patent 5043488: slow addition of nitric acid to acetone produces an unknown explosive", probably ethylnitrolic acid (1-Nitro-1-oximinoethane).
CH3C(NOH)NO2
"was prepared by mixing acetone with nitric acid (of 24% concentration) and a little fuming HNO3 and allowing the mixture to stand for 8 days at room
temperature. An ether extraction gave on evaporation some acetylmethylnitrolic acid"
Beil 3,621 and
R. Behrend & H. Tryller, Ann283,221- 3( 1894)
"... right after the strong oxidation left behind was a clear, thick yellow oil of a pungent odor. According to Jahresbericht über Fortschritte der
Chemie (1902), Behrend and Tryller, p. 1075-77 this oil contained one-third to half acetylmethylnitrolic acid (CH3.CO.C(NOH).NO2) (cryst., mp. 62
deg., very decomposable) and other byproducts, including pyruvic and oxalic acids. They say in the same instance methyethyl ketone affords CH3COOH,
HCOOH, and considerable amounts of ethylnitrolic acid and dinitroethane"
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I would imagine the reaction of nitrous acid on acetone would produce a nitrolic acid. There are some other references describing nitrous acid
reacting with oximes to produce nitrolic acids.
Probably various different products are forming in your reaction, depending on the degree of oxidation.
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