xwinorb
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MeCN + H2SO4
I have one question on acetonitrile : Does it react with sulfuric acid ? I used Google, could not find a conclusive answer.
If the answer is yes, could someone please post what the reaction produces.
One MSDS says acetonitrile is incompatible with H2SO4, but I think there are procedures that use them both. One example would be the Ritter reaction,
right ? BTW, I am just mentioning the Ritter reaction here as a case example.
Also, I think H2SO4 + NaCN or KCN would generate HCN ( cyanide ), right ? What about MeCN + H2SO4 ?
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kclo4
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H2SO4 I think would be able to cause hydrolysis leading to the amide and then to a carboxylic acid.
Probably pretty hard to get CN- out of it, but probably possible so I'd be careful.
http://en.wikipedia.org/wiki/Nitrile#Reactions_of_nitriles might be of interest to you if you haven't seen it, reviewed it recently.
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Nicodem
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Acetonitrile does react with H2SO4, because if you pour a stoichiometric 1:1 mixture into water you get acetamide rather than recover MeCN. It is hard
to define what you obtain from the reaction of MeCN with H2SO4, because it is dynamic equilibrium of different electrophilic species rather than a
solution of a definable compound.
In principle the reaction should be reversible, and if you would quench the mixture with pyridine instead of water, you should be able to recover
unchanged acetonitrile, but I doubt anybody ever tried.
And no, no cleavage to cyanide occurs.
[Edited on 2/10/2009 by Nicodem]
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Formatik
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Alkalies, as well as aq. HCl or H2SO4 when heated with acetonitrile "soaponifies" it to acetic acid and ammonia. With fuming sulfuric acid (28% SO3),
ice-salt cooled reaction with acetonitrile yields acetyl-acetamidine-N-sulfonic acid (CH3.C(:N.SO3H).NH.CO.CH3). With SO3 the compound (CH3.CN)3.2SO3
forms. (Ref.: Beilstein).
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unionised
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The reaction of conc H2SO4 and ACN can be dangerously violent.
It produces a mixture of products- mainly the cyclic trimer.
[Edited on 3-10-09 by unionised]
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JohnWW
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CH3CN being an ester of a weak acid, its reaction with H2SO4 would certainly cause hydrolysis, with the evolution of HCN gas (very toxic) and probably
formation of dimethyl sulfate (also toxic).
Depending on the concentration of acid and the temperature and pressure, there may also be other products. The formation of the aromatic trimer of
CH3CN, 1,3,5-trimethyl-2,4,6-triazine, (which would not require H2SO4 except possibly as a catalyst), as well as that of HCN, 1,3,5-triazine, would be
energetically favored, but would require high pressure to occur substantially.
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UnintentionalChaos
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Quote: Originally posted by JohnWW  | CH3CN being an ester of a weak acid, its reaction with H2SO4 would certainly cause hydrolysis, with the evolution of HCN gas (very toxic) and probably
formation of dimethyl sulfate (also toxic).
Depending on the concentration of acid and the temperature and pressure, there may also be other products. The formation of the aromatic trimer of
CH3CN, 1,3,5-trimethyl-2,4,6-triazine, (which would not require H2SO4 except possibly as a catalyst), as well as that of HCN, 1,3,5-triazine, would be
energetically favored, but would require high pressure to occur substantially. |
It's not an ester any more than methyl bromide is an ester. There is no ester functionality; it's simply an alkyl nitrile. Cleavage in the way you
describe would require cleaving of a carbon-carbon bond which is not one of H2SO4's specialties.
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'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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panziandi
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Dilute sulphuric acid would hydrolyse the acetonitrile to acetamide and then to acetic acid and ammonium hydrogen sulphate, as shown below:
CH3CN + H2O =(H2SO4)=> CH3CONH2
CH3CONH2 + H2SO4 + H2O => CH3COOH + NH5SO4
Reaction with concentrated sulphuric acid will likely be a mixture of various reactions.
Strong acids (both Lewis acids and strong Brønsted acids) are able to attack nitriles forming ionic species, such as is seen in the Houben-Hoesch
reaction. I do not know if suilphuric acid is strong enough to do this off the top of my head.
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