Sciencemadness Discussion Board - Propane + HNO3 400C + 10bar vapor phase?

Propane + HNO3 400C + 10bar vapor phase?

chucknorris - 16-12-2012 at 10:31

Giving a thought for nitrating short chain paraffins, I was interested in the idea of making titanium pipe, inert N2 atmosphere and 10bar pressurised system so that the propane gas was released through the pipe and from other pipe at the junction comes HNO3 and the joint is heated up to 400C temp so both will be in high vapor phase. What would be the resultant products?

bfesser - 16-12-2012 at 11:02

Try a little research.
http://pubs.acs.org/doi/abs/10.1021/ie50603a025

I think you're going to be dealing with NO2 at those temperatures, but I'm not positive:
4 HNO3 → 2 H2O + 4 NO2 + O2

kristofvagyok - 16-12-2012 at 12:12

Quote: Originally posted by chucknorris

Giving a thought for nitrating short chain paraffins, I was interested in the idea of making titanium pipe, inert N2 atmosphere and 10bar pressurised system so that the propane gas was released through the pipe and from other pipe at the junction comes HNO3 and the joint is heated up to 400C temp so both will be in high vapor phase. What would be the resultant products?

The main resultant product would be a loss of a few finger, maybe one eye and a lot blood. Industrial chemistry with unfriendly reagents, high pressure and a lot heat could easily cause great problems.

Here is an easier method for nitration propane: http://pubs.acs.org/doi/abs/10.1021/ie50583a023

They give lower yields, but it works on atmospheric pressure, doesn't require any special things, not even a titanium pipe and the not reacted propane could be easily recirculated, the only thing what is needed to fed is the commercial 67% HNO3.

hissingnoise - 16-12-2012 at 13:13

Quote:

Propane + HNO3 400C + 10bar vapor phase?

This is hardly a reaction to be conducted in a home setting!
Dinitropropane isn't a reaction product in any case and only ~38% HNO₃ reacts to form nitroparaffins!
Other products include aldehydes, alcohols, CO. NO and other nitroxides . . .

AndersHoveland - 31-1-2013 at 23:28

The vapor phase nitration of propane with nitric acid at 420 °C produces various nitroalkanes in 40% yield total. The yield for nitromethane is only 4%, for nitroethane 10%, for 2-Nitropropane the yield is 16%.
The various nitroalkanes are then separated by distillation. Nitromethane boils off first at 101 °C, then nitroethane at 114 °C. The vapor-phase nitration can alternatively be done with nitrogen dioxide, giving better yields, with the additional advantage that the products contain less 2-nitropropane.

2-Nitropropane boils at 120 °C. 1-Nitropropane boils at 131 °C. 2-Nitropropane is a carcinogen, breathing of its vapor should be avoided.

This is actually the industrial process used to make nitroethane (used as a solvent), where nitromethane results as a byproduct. The 2-nitropropane must be destroyed, and removed from the final products due to its toxicity.

[Edited on 1-2-2013 by AndersHoveland]

testimento - 25-6-2013 at 03:26

My friend told me that this setup would work:

-You make everything from stainless steel so it can hold 10 bars, nitric will eat through normal steel at 400c in minutes but it can hold very nicely with high grade stainless like 316 grade
-The reactor you coat it with clay or some stuff from the hot part where the reagents will meet at vapor phase, not necessary but its better to the nitric to eat the clay before the steel so it can hold up atleast few runs
-In one pot you put ethanol
-In another pot on the side you will put hno3
-You will flush the system with some gas like co2 or propane to get air out
-Then you will heat the both pots to get them boil and increase the pressure to 10 bar
-Then you will release a little from valve so the vapor gases go to the reactor which is just pipe with etoh coming from other end and hno3 from other end and in the middle is the output pipe, you control the pressure with flow rate and boiling power of the etoh and hno3 pots, higher boiling power allows for higher flow rate bot too high may decrease yield or cause dangerous type of nitrite formation
-You heat the reactor to 400c and the stuff will meet and react to make ethyl nitrite and immediately turn into nitroethane
-Keep the flow rate so that pressure stays at 10bar, you will get cheap pressure gauges from everywhere, mount it at the ethanol pipe so it wont be eaten by nitric and fly through your roof
-If you put too high flow rate the stuff will react too fast and the amount of ethyl nitrite can be high enough to cause detonation, in normal situations it is formed only in milligrams or maximum grams a second which has no enough power to rupture the reactor even if it happens to detonate
-One should get at least 60-70% nitroethane from this
-You can also use ethylene or other gases created in the reactor directly with electrolysis or other methods to get higher yield

[Edited on 25-6-2013 by testimento]