Difference between revisions of "Raschig hydroxylamine process"
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==Process chemistry== | ==Process chemistry== | ||
The synthesis is a three step process. First, [[ammonia]] is [[Oxidation|oxidized]] in air to give nitrogen oxides (preferably [[dinitrogen trioxide]]), which react with [[ammonium carbonate]] to give [[ammonium nitrite]]: | The synthesis is a three step process. First, [[ammonia]] is [[Oxidation|oxidized]] in air to give nitrogen oxides (preferably [[dinitrogen trioxide]]), which react with [[ammonium carbonate]] to give [[ammonium nitrite]]: | ||
| − | : | + | :2 NH<sub>3</sub> + 3 O<sub>2</sub> → N<sub>2</sub>O<sub>3</sub> + 3 H<sub>2</sub>O |
| − | :N<sub>2</sub>O<sub>3</sub> + (NH<sub>4</sub>)<sub>2</sub>CO<sub>3</sub> → | + | :N<sub>2</sub>O<sub>3</sub> + (NH<sub>4</sub>)<sub>2</sub>CO<sub>3</sub> → 2 NH<sub>4</sub>NO<sub>2</sub> + CO<sub>2</sub> |
The ammonium nitrite is reduced with [[sulfur dioxide]] in the presence of ammonia at 5 °C to give [[diammonium hydroxylaminedisulfonate]]: | The ammonium nitrite is reduced with [[sulfur dioxide]] in the presence of ammonia at 5 °C to give [[diammonium hydroxylaminedisulfonate]]: | ||
| − | :NH<sub>4</sub>NO<sub>2</sub> + | + | :NH<sub>4</sub>NO<sub>2</sub> + 2 SO<sub>2</sub> + NH<sub>3</sub> → (NH<sub>4</sub>)<sub>2</sub>[HON(SO<sub>3</sub>)<sub>2</sub>] |
The disulfonate is then hydrolyzed at 100 °C to give [[hydroxylamine sulfate]]: | The disulfonate is then hydrolyzed at 100 °C to give [[hydroxylamine sulfate]]: | ||
:(NH<sub>4</sub>)<sub>2</sub>[HON(SO<sub>3</sub>)<sub>2</sub>] + H<sub>2</sub>O → NH<sub>2</sub>OH·H<sub>2</sub>SO<sub>4</sub> + (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> | :(NH<sub>4</sub>)<sub>2</sub>[HON(SO<sub>3</sub>)<sub>2</sub>] + H<sub>2</sub>O → NH<sub>2</sub>OH·H<sub>2</sub>SO<sub>4</sub> + (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> | ||
Revision as of 17:50, 3 July 2010
The Raschig hydroxylamine synthesis is an industrial process for producing hydroxylamine. The hydroxylamine is generally used in the manufacture of caprolactam and hence nylon-6, although it also finds use in the semiconductor industry.
Process chemistry
The synthesis is a three step process. First, ammonia is oxidized in air to give nitrogen oxides (preferably dinitrogen trioxide), which react with ammonium carbonate to give ammonium nitrite:
- 2 NH3 + 3 O2 → N2O3 + 3 H2O
- N2O3 + (NH4)2CO3 → 2 NH4NO2 + CO2
The ammonium nitrite is reduced with sulfur dioxide in the presence of ammonia at 5 °C to give diammonium hydroxylaminedisulfonate:
- NH4NO2 + 2 SO2 + NH3 → (NH4)2[HON(SO3)2]
The disulfonate is then hydrolyzed at 100 °C to give hydroxylamine sulfate:
- (NH4)2[HON(SO3)2] + H2O → NH2OH·H2SO4 + (NH4)2SO4
References
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