Microtek
September 2nd, 2003, 08:50 AM
Thus far, I have been content to view nitric acid of sufficient concentration to produce RDX as "highly concentrated". However, now that I am moving on to HMX, the need has arisen to acertain that the acid is more than 85 % concentrated ( the minimum required to get a measurable yield of RDX ).
An NaOH soln of known concentration was prepared by dissolving solid NaOH in deionized water and titrating a carefully weighed amount of pure benzoic acid in neutral ethanol.
- A batch of ca. 50 % H2SO4 was heated to 170 C to drive off most of the water. Titration showed a concentration of 90 %.
- 100 mL of this 90 % H2SO4 was mixed with 100 mL 62 % HNO3 in a retort of 250 mL capacity,
and distilled at atmospheric pressure on a sandbath on an electric hotplate ( the hotplate is for cooking, and was set at 50 % ). No cooling was applied to the condenser.
- After 3 hours, no more distillate was coming over, and the collected acid was seen to be distinctly yellow with NOx.
- About 50 mL distillate is recovered from this batch size, which is a quite good yield.
- A sample of the distillate was titrated and found to be 88.00 ( +/- 0.04 ) % concentrated ( but note that NOx was not removed prior to titration, so actual value is slightly lower ).
- The rest of the distillate was mixed with 50 mL 96 % H2SO4 from a lab supply and redistilled under the same conditions as before.
- Almost the same amount of distillate was recovered and was purged of NOx by bubbling dry air through it and adding about 0.25 g urea with heating ( the bubbling had to be continued for more than 10 minutes, and was much more effective at elevated temps ( 50 C )).
- Once the acid was completely clear, a sample was titrated and found to be 95.88 (+/- 0.08) %
I believe that the acid was diluted somewhat by the purging process, and that some of this dilution could have been avoided by not using urea and bubbling at elevated temps from the beginning.
An NaOH soln of known concentration was prepared by dissolving solid NaOH in deionized water and titrating a carefully weighed amount of pure benzoic acid in neutral ethanol.
- A batch of ca. 50 % H2SO4 was heated to 170 C to drive off most of the water. Titration showed a concentration of 90 %.
- 100 mL of this 90 % H2SO4 was mixed with 100 mL 62 % HNO3 in a retort of 250 mL capacity,
and distilled at atmospheric pressure on a sandbath on an electric hotplate ( the hotplate is for cooking, and was set at 50 % ). No cooling was applied to the condenser.
- After 3 hours, no more distillate was coming over, and the collected acid was seen to be distinctly yellow with NOx.
- About 50 mL distillate is recovered from this batch size, which is a quite good yield.
- A sample of the distillate was titrated and found to be 88.00 ( +/- 0.04 ) % concentrated ( but note that NOx was not removed prior to titration, so actual value is slightly lower ).
- The rest of the distillate was mixed with 50 mL 96 % H2SO4 from a lab supply and redistilled under the same conditions as before.
- Almost the same amount of distillate was recovered and was purged of NOx by bubbling dry air through it and adding about 0.25 g urea with heating ( the bubbling had to be continued for more than 10 minutes, and was much more effective at elevated temps ( 50 C )).
- Once the acid was completely clear, a sample was titrated and found to be 95.88 (+/- 0.08) %
I believe that the acid was diluted somewhat by the purging process, and that some of this dilution could have been avoided by not using urea and bubbling at elevated temps from the beginning.