Difference between revisions of "Bayer hydrazine process"
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| − | The '''Bayer hydrazine process''' is a modification of the [[Raschig process]] for the industrial production of [[hydrazine]]. Both processes are based around the oxidation of [[ammonia]] to hydrazine with [[hypochlorite]], but the Bayer process traps the hydrazine as [[acetone azine]] before hydrolyzing the [[azine]] in a separate step.<ref name="Bayer">{{citation | inventor1-last = Eichenhofer | inventor1-first = Kurt-Wilhelm | inventor2-last = Schliebs | inventor2-first = Reinhard | assignee = Bayer | title = Production of ketazines | country-code = US | patent-number = 3965097 | issue-date = 1976-06-22}}.</ref><ref name="H&W">{{Holleman&Wiberg|page=619}}.</ref> | + | The '''Bayer hydrazine process''' is a modification of the [[Raschig process]] for the industrial production of [[hydrazine]]. Both processes are based around the oxidation of [[ammonia]] to hydrazine with [[hypochlorite]], but the Bayer process traps the hydrazine as [[acetone azine]] before hydrolyzing the [[azine]] in a separate step.<ref name="Bayer">{{citation | inventor1-last = Eichenhofer | inventor1-first = Kurt-Wilhelm | inventor2-last = Schliebs | inventor2-first = Reinhard | assignee = Bayer | title = Production of ketazines | country-code = US | patent-number = 3965097 | issue-date = 1976-06-22}}.</ref><ref name="H&W">{{Holleman&Wiberg|page=619}}.</ref> The process is operated by Bayer at its Leverkusen plant in western Germany.<ref>{{citation | title = Material Flowsheet CHEMPAK LEV | url = http://www.chempark.com/medien/allgemein/downloads/VERBLEV20090430mFLogoENG.pdf | publisher = Bayer | date = 2009-04-28 | accessdate = 2010-07-03}}.</ref> |
The oxidation of ammonia by hypochlorite proceeds by a [[chloramine]] intermediate:<ref name="C&W">{{Cotton&Wilkinson5th|page=317}}.</ref> | The oxidation of ammonia by hypochlorite proceeds by a [[chloramine]] intermediate:<ref name="C&W">{{Cotton&Wilkinson5th|page=317}}.</ref> | ||
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:2NH<sub>2</sub>Cl + N<sub>2</sub>H<sub>4</sub> → 2NH<sub>4</sub>Cl + N<sub>2</sub> | :2NH<sub>2</sub>Cl + N<sub>2</sub>H<sub>4</sub> → 2NH<sub>4</sub>Cl + N<sub>2</sub> | ||
The disproportionation reaction is "rather fast once some hydrazine has been formed", and a [[gelatin]] inhibitor must be used in the Raschig process to obtain appreciable yields of hydrazine.<ref name="C&W"/> | The disproportionation reaction is "rather fast once some hydrazine has been formed", and a [[gelatin]] inhibitor must be used in the Raschig process to obtain appreciable yields of hydrazine.<ref name="C&W"/> | ||
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| + | The Bayer process adds acetone to the reaction mixture to trap the hydrazine as acetone azine, which is inert to chloramine. The mechanism appears to be slightly different from the Raschig process, with chloramine reacting with acetone to for [[3,3-dimethyloxazidirine]], which then reacts with ammonia to form [[acetone hydrazone]]. The hydrazone then reacts with a further equivalent of acetone to form the azine, which is the isolated product.<ref name="Bayer"/> | ||
==References== | ==References== | ||
Revision as of 08:49, 3 July 2010
The Bayer hydrazine process is a modification of the Raschig process for the industrial production of hydrazine. Both processes are based around the oxidation of ammonia to hydrazine with hypochlorite, but the Bayer process traps the hydrazine as acetone azine before hydrolyzing the azine in a separate step.[1][2] The process is operated by Bayer at its Leverkusen plant in western Germany.[3]
The oxidation of ammonia by hypochlorite proceeds by a chloramine intermediate:[4]
- NH3 + ClO− → NH2Cl + OH−
- NH3 + NH2Cl + OH− → N2H4 + Cl− + H2O
However, the hydrazine is prone to a disproportionation reaction in the presence of chloramine:
- 2NH2Cl + N2H4 → 2NH4Cl + N2
The disproportionation reaction is "rather fast once some hydrazine has been formed", and a gelatin inhibitor must be used in the Raschig process to obtain appreciable yields of hydrazine.[4]
The Bayer process adds acetone to the reaction mixture to trap the hydrazine as acetone azine, which is inert to chloramine. The mechanism appears to be slightly different from the Raschig process, with chloramine reacting with acetone to for 3,3-dimethyloxazidirine, which then reacts with ammonia to form acetone hydrazone. The hydrazone then reacts with a further equivalent of acetone to form the azine, which is the isolated product.[1]
References
- ↑ 1.0 1.1 Eichenhofer, Kurt-Wilhelm; Schliebs, Reinhard (Bayer) Production of ketazines. US Patent 3965097, issued 22 June 1976.
- ↑ Holleman, A. F.; Wiberg, E. Inorganic Chemistry; Academic Press: San Diego, 2001; p 619. ISBN 0-12-352651-5.
- ↑ Material Flowsheet CHEMPAK LEV; Bayer, 2009-04-28, <http://www.chempark.com/medien/allgemein/downloads/VERBLEV20090430mFLogoENG.pdf>. (accessed 3 July 2010).
- ↑ 4.0 4.1 Cotton, F. Albert; Wilkinson, Geoffrey Advanced Inorganic Chemistry, 5th ed.; Wiley-Interscience: New York, 1988; p 317. ISBN 0-471-84997-9.
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