Sciencemadness Discussion Board - Liquid-phase nitration of n-butane

Liquid-phase nitration of n-butane

Grizli7 - 1-9-2021 at 12:14

Hello everyone. We are talking about Konovalov's reaction. I'm going to set up an experiment, but with a number of significant differences. Unfortunately, there is very little information about the detailed description of the experiment. The author used a glass sealed tube inside which there was a 13.5% solution of nitric acid and hydrocarbon. The reaction took place for 4-5 hours at a temperature of 140-150 C.
I understand that this excluded the toxic effect on the reaction mass. But in my case, a stainless steel pipe will be used. Brand unknown. But in the "past life" the pipe was used to fuel rockets - so I assume that the alloying content is high. I will also passivate first with hydrochloric acid and then with nitric acid.
As you know, the main problem of liquid-phase nitration is that the hydrocarbon does not dissolve in nitric acid, but nitration products are perfectly soluble in it, undergoing further nitration and oxidation. And that worries me the most. I could not find information anywhere about which products are formed and in what quantity. And what the quantity during process after 1 hour, 2 hour etc. I can only assume that all nitro products: nitroethane, nitromethane, 1-nitropropane, 1-nitrobutane, 2-nitrobutane - all of them will undergo further nitration. All I found sounds like an increase in polynitro compounds is facilitated by the concentration of nitric acid, temperature and an increase in pressure. There is also very little information on the explosive properties, sensitivity of di and polynitro compounds. For example, Urbansky, 1,2-dinitroethane is described in more detail than 1,1-dinitroethane. Maybe someone has worked with substances such as trinitroethane, dinitromethane, trinitromethane, tetranitromethane, dinitrobutane, etc. Dinitromethane worries me most of all, but its properties indicate that at temperatures above 40C it decomposes with the release of dioxide. If I understand correctly, then it should not form at all during the reaction, but preassure about 24 bar.. I also plan to use a 10: 1 molar ratio of butane to nitric acid to increase process safety. I suppose that the more nitric acid is consumed for nitration, the less it will remain for nitration of nitro products. But here, too, everything is not so simple - the easiest to replace is the tertiary atom, the second is more difficult, and the first is even more difficult, i.e. the formation of 1-nitrobutane will occur very quickly, and as soon as it is formed, its further nitration and oxidation will begin. To prepare the solution, high-purity nitric acid and butane of technical qualification from a gas filling station will be used. This means that ethyl mercaptan and possibly gas condensate, which is gasoline kerosene fractions, will also get into the reaction.
Those who conducted the experiment said that a liquid with a large amount of dioxide is obtained at the exit, and here another question is it safe to use sodium bicarbonate or urea to remove it, like nitroethane and nitromethane react with carbonates? And so I will briefly summarize the questions:
1.) Will passivated stainless steel be toxic?
2.) What di and polynitro compounds are formed and in what quantity?
3.) What is the most dangerous?
4.) Which molar ratio is best?
5.) How to remove the dioxide before overclocking?
6.) Is it possible to add boric acid before overclocking if there are polynitro compounds?
Thank you.

Swinfi2 - 2-9-2021 at 02:03

Not sure if this goes without saying, but it sounds like you're making explosives, inside an apparatus that already constitutes a pipe bomb.

I could be wrong but do you like being in one piece?

Also I'd be pretty particular about the grade of steel with nitric acid, I think you need ceramic or Teflon liners or it will corrode rapidly... before you add the heat and pressure...

karlos³ - 2-9-2021 at 02:21

Quote: Originally posted by Swinfi2

Not sure if this goes without saying, but it sounds like you're making explosives, inside an apparatus that already constitutes a pipe bomb.

I could be wrong but do you like being in one piece?

Well, one of our members actually build successfully a functioning apparatus for the direct nitration of even shorter alkanes, C1-C3.
Scary, too scary for me personally.

But he was skilled enough to realize that project, despite the level of danger coming with it.
I can't find it right now, but I'm sure somebody else knows which project I'm talking about?
Nope, can't find the thread.

Swinfi2 - 2-9-2021 at 03:40

I do agree you can do anything if you're mindful of the risks and are careful enough to survive the process.

That said I still have the scar from trying molten NaOH electrolysis lol.
I'd pass on direct nitrations.

Grizli7 - 2-9-2021 at 07:12

Quote: Originally posted by Swinfi2

Not sure if this goes without saying, but it sounds like you're making explosives, inside an apparatus that already constitutes a pipe bomb.

I could be wrong but do you like being in one piece?

Also I'd be pretty particular about the grade of steel with nitric acid, I think you need ceramic or Teflon liners or it will corrode rapidly... before you add the heat and pressure...

If I'm not mistaken, the composition of the melange is 24% nitric tetroxide and 72% nitric acid and a little crystalline iodine as a corrosion inhibitor - something like this was pumped through the pipe. I had an idea to make a PTFE pipe inside, but there was no money.

[Edited on 2-9-2021 by Grizli7]

Grizli7 - 2-9-2021 at 07:14

Quote: Originally posted by karlos³

Quote: Originally posted by Swinfi2

Not sure if this goes without saying, but it sounds like you're making explosives, inside an apparatus that already constitutes a pipe bomb.

I could be wrong but do you like being in one piece?

Perhaps you will remember a little later. It would be great if the person shared their experience. Successful experience.

Grizli7 - 2-9-2021 at 07:21

See what's the matter. At one time, I tried to find as much information as possible on this issue and never once did I come across information that the reaction ended in an explosion. Although I understand perfectly well that many books on chemistry are written by theorists who simply rewrote from other books and did not even conduct an experiment.
On the other hand, if you think about it, then all the differences are only in the material of the case, since according to such a characteristic as the critical detonation diameter, neither Konovalov nor I pass. Yes, a sealed glass ampoule has a negligible amount of substance measured, let it be 10-15 milliliters, but it is not so much the quantity that matters as the molar concentration of the substance per unit volume. Or I'm wrong?

Boffis - 2-9-2021 at 11:42

Hi Grizli7, have you looked at the original papers by Konovalov or Markovnikov? The references are Nos 3 and 4 in the attached paper. They are both available from the French Gallica site for free.

Attachment: Nitration of paraffins with nitronium hexafluorophosphate ProNatAcadSci Olah et al 1997.pdf (173kB)
This file has been downloaded 303 times

karlos³ - 2-9-2021 at 20:18

Quote: Originally posted by Grizli7

Perhaps you will remember a little later. It would be great if the person shared their experience. Successful experience.

Could not remember it.... had to search it the hard way, with a twenty year old search engine

But here it is

http://www.sciencemadness.org/talk/viewthread.php?tid=13633&...

Triflic Acid - 3-9-2021 at 05:19

Don't do this if you want nitrobutane. Do this instead: https://pubs.rsc.org/en/content/articlelanding/2001/cc/b1023... a bit of catalyst goes a long way. N Hydroxy phalamide.

Grizli7 - 4-9-2021 at 09:35

Quote: Originally posted by Boffis

Hi Grizli7, have you looked at the original papers by Konovalov or Markovnikov? The references are Nos 3 and 4 in the attached paper. They are both available from the French Gallica site for free.

What an interesting electronic library, but I didn't know. Links checked but there are other substances.

Grizli7 - 4-9-2021 at 09:46

Quote: Originally posted by karlos³

Quote: Originally posted by Grizli7

Perhaps you will remember a little later. It would be great if the person shared their experience. Successful experience.

Could not remember it.... had to search it the hard way, with a twenty year old search engine

But here it is

http://www.sciencemadness.org/talk/viewthread.php?tid=13633&...

The branch is very interesting. But there it is mainly about vapor-phase nitration - this is completely different. In particular, with a competent approach, it is safer, since according to the 4th rule of Hess di and polynitro compounds are not formed, since they safely fall apart on the way to the reactor when the temperature reaches 260C. And they are the ones who bother me.