PrimoPyro
August 6th, 2002, 05:56 AM
Here is a gift for your search engine, from a discussion at another bullitin board I love to frequent. I present to you the greatest gift anyone can give: information. :p
I'm simply going to copy the thread here for the full discussion, as more information came out in later posts than was originally presented in the first post by the author.
Author:
Preparation of 100% nitric acid
J. Org. Chem. 25, 469-470 (1960)
(a) Nitric acid (6.79 g.; 0.108 mole as 52.72 g. of a 12.88% solution) was carefully neutralized, with cooling, by addition of 4.32 g. (0.108 mole) of sodium hydroxide dissolved in the minimum amount of water. The water was removed by distillation and the dry salt was treated with concentrated sulfuric acid (18 ml, 0.32 mole).
Distillation at atmospheric pressure in the absence of sunlight gave 5.6g (0.089 mole) of 100% nitric acid, bp 80-83°C (82% recovery).
(b) Potassium nitrate (14.2 g.; 0.07 mole) and 31.1 ml. (0.56 mole) of concentrated sulfuric acid gave, upon distillation, 7.1 g. of 100% bp 78-82°C (81% recovery).
User A:
I've tried both KNO3/H2SO4 and HNO3/H2SO4 distillations at ordinary pressure and never got 100 % HNO3. The density was between 1,49 and 1,505. This indicates about 95% (dissolved NO2 not included in this calculation). I know of one literature reference where they claimed that distillation under reduced pressure below 0 degree centigrade is necessary to obtain almost pure acid.
Of course, 95% is better than commercially available 65-70% ...
Author:
Strange, in this article they are even working with nitric acid with a isotopically marked nitrogen atom, so one would think that they were extra careful when doing it. Perhaps it has something to do with the small batch size?
User A:
I've done the preparation on a liter-scale with much longer heating than on a small scale. My distillate was always yellow colored due to NO2 formation.
Moderator A:
The regularly available azeotropic HNO3 can be concentrated by distilling it from the same volume of H2SO4, preferably under a slight vacuum. I've done this big scale with 6L RB flasks and it worked great.
User B:
In my younger dayes (explosives yeahh)I did like osmium but two times (mix salpeter acid with sulfuric and destilate, then mix the product with sulfuric and destilate againAdding a nitric salt (KNO3, NaNO3) to salpeter result in a big chunc off nonsoluble sodium or potasium sulphate.
User C:
"To 25 ml of (cooled) concentrated sulfuric acid in a distillation flask add 30 g of previously dried potassium nitrate and a little bit of silver nitrate (swirling). Close with stopper and let sit for 1 hour (to complete conversion). Then distil carefully (I guess it means "slowly" here). The brown-yellow forerun is discarded, only the fraction in the distilling range from 83 to 85 °C is collected. The distillation is finished when red fumes begin to form in the condenser."
They also recommend vacuum distillation for the production of larger amounts of nitric acid in combination with full glass apparatus with ground glass joints. The joints are lubricated with sulfuric or phosphoric acid.
Boiling point of 100 % nitric acid: 83 °C (atmospheric pressure), 36-38 °C (26 mbar)
[Translated from:
"Jander-Blasius: Lehrbuch der analytischen und praeparativen anorganischen Chemie", 12. ed., 1985, S. Hirzel Verlag, Stuttgart]
User D:
The joints are lubricated with concentrated sulfuric acid? I understand why... but damn, I never realized how nasty and dangerous that acid would be to distill.
End Thread.
It is still debatable whether the claims in the article are truthful, but regardless, it good to have more evidence of NOT needing N2O5 to produce anhydrous 100% HNO3. I hate oxyacid anhydrides.
PrimoPyro
I'm simply going to copy the thread here for the full discussion, as more information came out in later posts than was originally presented in the first post by the author.
Author:
Preparation of 100% nitric acid
J. Org. Chem. 25, 469-470 (1960)
(a) Nitric acid (6.79 g.; 0.108 mole as 52.72 g. of a 12.88% solution) was carefully neutralized, with cooling, by addition of 4.32 g. (0.108 mole) of sodium hydroxide dissolved in the minimum amount of water. The water was removed by distillation and the dry salt was treated with concentrated sulfuric acid (18 ml, 0.32 mole).
Distillation at atmospheric pressure in the absence of sunlight gave 5.6g (0.089 mole) of 100% nitric acid, bp 80-83°C (82% recovery).
(b) Potassium nitrate (14.2 g.; 0.07 mole) and 31.1 ml. (0.56 mole) of concentrated sulfuric acid gave, upon distillation, 7.1 g. of 100% bp 78-82°C (81% recovery).
User A:
I've tried both KNO3/H2SO4 and HNO3/H2SO4 distillations at ordinary pressure and never got 100 % HNO3. The density was between 1,49 and 1,505. This indicates about 95% (dissolved NO2 not included in this calculation). I know of one literature reference where they claimed that distillation under reduced pressure below 0 degree centigrade is necessary to obtain almost pure acid.
Of course, 95% is better than commercially available 65-70% ...
Author:
Strange, in this article they are even working with nitric acid with a isotopically marked nitrogen atom, so one would think that they were extra careful when doing it. Perhaps it has something to do with the small batch size?
User A:
I've done the preparation on a liter-scale with much longer heating than on a small scale. My distillate was always yellow colored due to NO2 formation.
Moderator A:
The regularly available azeotropic HNO3 can be concentrated by distilling it from the same volume of H2SO4, preferably under a slight vacuum. I've done this big scale with 6L RB flasks and it worked great.
User B:
In my younger dayes (explosives yeahh)I did like osmium but two times (mix salpeter acid with sulfuric and destilate, then mix the product with sulfuric and destilate againAdding a nitric salt (KNO3, NaNO3) to salpeter result in a big chunc off nonsoluble sodium or potasium sulphate.
User C:
"To 25 ml of (cooled) concentrated sulfuric acid in a distillation flask add 30 g of previously dried potassium nitrate and a little bit of silver nitrate (swirling). Close with stopper and let sit for 1 hour (to complete conversion). Then distil carefully (I guess it means "slowly" here). The brown-yellow forerun is discarded, only the fraction in the distilling range from 83 to 85 °C is collected. The distillation is finished when red fumes begin to form in the condenser."
They also recommend vacuum distillation for the production of larger amounts of nitric acid in combination with full glass apparatus with ground glass joints. The joints are lubricated with sulfuric or phosphoric acid.
Boiling point of 100 % nitric acid: 83 °C (atmospheric pressure), 36-38 °C (26 mbar)
[Translated from:
"Jander-Blasius: Lehrbuch der analytischen und praeparativen anorganischen Chemie", 12. ed., 1985, S. Hirzel Verlag, Stuttgart]
User D:
The joints are lubricated with concentrated sulfuric acid? I understand why... but damn, I never realized how nasty and dangerous that acid would be to distill.
End Thread.
It is still debatable whether the claims in the article are truthful, but regardless, it good to have more evidence of NOT needing N2O5 to produce anhydrous 100% HNO3. I hate oxyacid anhydrides.
PrimoPyro