tom haggen
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Toluene and KNO3
Will toluene react with potassium nitrate at room temperature?
N/A
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woelen
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No, it will not. KNO3 is rather inert at room temperature.
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mnick12
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React in what way? I dont think KNO3 would react with toluene even at an elevated tempurature.
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hissingnoise
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Presumably toluene would react in a KNO3/H2SO4 mixture but I don't know to what extent.
Some MNT is probable, DNT possible but to get TNT this way would be very difficult and wasteful of acid, I think.
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ScienceSquirrel
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I reckon you could reflux potassium nitrate in toluene and nothing would happen.
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Mumbles
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I speak from experience that you can make MNT at least with some DNT impurity from KNO3/sulfuric acid.
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2bestyle
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Do you want to nitrify Toluene to Monnitrotoluene or do you want do oxidize it to Benzoic Acid? For the First one you could use a mixture of KNO3 and
Sulfuric Acid. For the second one you have to use Potassium permanganate.
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rrkss
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Nitration of Toluene is very tough and will require some very harsh conditions if that is what you are after. Mono-Nitro-Toluene can be made by
refluxing toluene in a mixture of Nitric Acid/Sulfuric acid or KNO3 in concentrated H2SO4. You might get some DNT but Nitro-groups are very
deactivating which means that the more Nitro groups you attach to the toluene, the more difficult it is to attach another one.
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mnick12
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Quote: Originally posted by rrkss  | | Nitration of Toluene is very tough and will require some very harsh conditions if that is what you are after. Mono-Nitro-Toluene can be made by
refluxing toluene in a mixture of Nitric Acid/Sulfuric acid or KNO3 in concentrated H2SO4. You might get some DNT but Nitro-groups are very
deactivating which means that the more Nitro groups you attach to the toluene, the more difficult it is to attach another one. |
I sorta disagree,
Toluene is generally very easy to mono- nitrate and even di- nitrate, as long as your reagents are not complety full of water. It is usually tri-
nitration that tends to be a problem, but if you are simply after a MNT then there is no need to reflux, and if you want DNT then just nitrate your
MNT at an elevated tempurature.
rrkss, mabe you are thinking of benzene? Benzene is quite a bit harder to nitrate, though I do not think you need to reflux just react for a longer
time.
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rrkss
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Well thinking about it more, you are right. The methyl group on toluene would slightly activate the ring making the first nitro easy to put on. TNT
seems like it would need very harsh conditions to make with two deactivating nitro groups and would most likely need heat + oleum to be a possibility.
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DJF90
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I disagree, even benzene is not that tough to mono-nitrate, requiring only a mixture of concentrated sulfuric and nitric acids, and temperature
regulation at about 55*C (in the procedures I've seen)... toluene is even more reactive and I would probably try the nitration at 0*C; methyl
m-nitrobenzoate is formed by nitration of methyl benzoate (in which the ring is deactivated by the ester group) at 5-10*C. Trinitration is
however pretty tough, although doesn't require oleum if you're willing to reflux for a longer period; chlorobenzene (in which the chlorine substituent
is a deactivating ortho/para directing group) can be trinitrated using fuming nitric acid (easy to make by distillation of 68% HNO3 from
equal volume of conc. sulfuric acid) and concentrated sulfuric acid at reflux for 35h, with replacement of the acid at the 17h mark... toluene would
be much easier than this, and I suspect that using the same nitrating mixture would have the reaction over in about 5-10hrs.
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densest
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"The Chemistry of Powder and Explosives", Tenney L. Davis, 1941-1943 on pp 141-153 shows the 3-step process for nitrating toluene. Each additional
NO2 requires stronger acid. There is a one-step procedure using a mercury catalyst which I don't have a reference handy. Both have approximately the
same yield. There are a number of side reactions which limit yield and reaction rate/temperature.
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hissingnoise
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Densest, was the mercury-catalysed nitration not the one which produced picric acid by refluxing 68% HNO3/benzene?
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Formatik
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Wilbrand's synthesis of TNT (Ann. 128 [1863], 178) consisted of heating toluene with mixed fuming sulfuric and fuming nitric acids for several days at
gentle boiling. Then adding water, washing obtained precipitate with water and drying, recryst. from alcohol.
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densest
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@hissingnoise - you're quite right! It's even in the same book a few pages down. I'll see if I can remember where I saw the 1-step TNT synthesis...
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hissingnoise
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The preparation of TNB by direct nitration is so difficult, it was found more economical to remove the methyl group of TNT by oxidation. . .
Densest, sure you're not mixing up TNT with PA?
[Edited on 5-4-2010 by hissingnoise]
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