Acetone azine
| Acetone azine | |
|---|---|
| IUPAC name | acetone azine diisopropylidenehydrazine |
| Identifiers | |
| InChI | InChI=1/C6H12N2/c1-5(2)7-8-6(3)4/h1-4H3 |
| InChIKey | PFLUPZGCTVGDLV-UHFFFAOYAR |
| Standard InChI | InChI=1S/C6H12N2/c1-5(2)7-8-6(3)4/h1-4H3 |
| Standard InChIKey | PFLUPZGCTVGDLV-UHFFFAOYSA-N |
| CAS number | [] |
| EC number | |
| ChemSpider | |
| SMILES | |
| Properties[1] | |
| Chemical formula | C6H12N2 |
| Molar mass | 112.17 g mol−1 |
| Appearance | colourless liquid |
| Density | 0.8390 g cm−3 |
| Melting point |
−12.5 °C |
| Boiling point |
133 °C |
| Refractive index (nD) | 1.4535 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
Acetone azine, Me2C=N–N=CMe2, is the condensation product of two equivalents of acetone with one equivalent of hydrazine. It is an intermediate in the industrial production of hydrazine by the Atofina–PCUK cycle.[2][3]
Laboratory preparation and use
On a laboratory scale, acetone azine is prepared by the direct reaction of acetone with hydrazine hydrate, with water being removed from the product by stirring with solid potassium hydroxide:[4][5] it is also commercially available. It is a useful precursor to acetone hydrazone[5][6] and hence to 2-diazopropane,[6][7][8] both of which must be prepared immediately before use and cannot be stored.[5][8]
As well as its use as an intermediate in organic synthesis, the coordination chemistry of acetone azine (as a ligand) has also been studied.[9][10]
Atofina–PCUK process
The industrial preparation of acetone azine[2] might, at first sight, appear to be the reverse of the laboratory procedure: the azine is produced from acetone hydrazone, and then hydrolyzed to give hydrazine and acetone. The interest in preparing the azine is that it can be removed from the initial reaction mixture as an azeotrope with water:[3] in both laboratory practice and the Atofina–PCUK process, the aim is to avoid directly handling the unstable acetone hydrazone.
The Atofina–PCUK process produces acetone azine from acetone (2 eq.), ammonia (2 eq.) and hydrogen peroxide (1 eq.). The first step is the formation of acetone imine, Me2C=NH; this is then oxidized by hydrogen peroxide through a complex mechanism to give 3,3-dimethyloxaziridine, which reacts with a further molecule of ammonia to produce acetone hydrazone. The hydrazone then condenses with a further molecule of acetone to produce the azine. The acetone azine product is distilled out of the reaction mixture as its azeotrope with water (n(H2O)/n(azine) = 6).[3]
The hydrolysis of the azine is acid-catalyzed, hence the need to isolate the azine from the initial ammonia-containing reaction mixture. It is also endothermic,[11] and so requires an increase in temperature (and pressure) to shift the equilibrium in favour of the desired products: acetone (which is recycled) and hydrazine hydrate.[3] The reaction is carried out by simple distillation of the azeotrope: typical conditions are a pressure of 8 bar and temperatures of 130 °C at the base of the column and 179 °C at the top of the column. The hydrazine hydrate (30–45% aqueous solution) is run off from the base of the column, while the acetone is distilled off from the top of the column and recycled.[3]
References
- ↑ CRC Handbook of Chemistry and Physics, 62nd ed.; Weast, Robert C., Ed.; CRC Press: Boca Raton, FL, 1981; p C-74. ISBN 0-8493-0462-8.
- ↑ 2.0 2.1 Schirmann, Jean-Pierre; Combroux, Jean; Delavarenne, Serge Yvon (Produits Chimiques Ugine Kuhlmann) Method for preparing azines and hydrazones. US Patent 3972878, issued 3 August 1976. Schirmann, Jean-Pierre; Tellier, Pierre; Mathais, Henri, et al. (Produits Chimiques Ugine Kuhlmann) Process for the preparation of hydrazine compounds. US Patent 3978049, issued 31 August 1976.
- ↑ 3.0 3.1 3.2 3.3 3.4 Schirmann, Jean-Pierre; Combroux, Jean; Delavarenne, Serge Y. (Atochem) Preparation of a concentrated aqueous solution of hydrazine hydrate. US Patent 4724133, issued 9 February 1988.
- ↑ Curtius, T.; Thun, K. J. Prakt. Chem. 1891, 44, 161.
- ↑ 5.0 5.1 5.2 Day, A. C.; Whiting, M. C. Acetone hydrazone. Org. Synth. 1970, 50, 3, <http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6p0010>; Coll. Vol., 6, 10.
- ↑ 6.0 6.1 Staudinger, H.; Gaule, A. Ber. Dtsch. Chem. Ges. 1916, 49, 1897.
- ↑ Day, A. C.; Raymond, P.; Southam, R. M.; Whiting, M. C. J. Chem. Soc. C 1966, 467.
- ↑ 8.0 8.1 Andrews, S. D.; Day, A. C.; Raymond, P.; Whiting, M. C. 2-Diazopropane. Org. Synth. 1970, 50, 27, <http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6p0392>; Coll. Vol., 6, 392.
- ↑ Gudkova, A. S.; Reutov, O. A.; Aleinikova, M. Ya. Izv. Akad. Nauk SSSR, Otdel. Khim. Nauk 1962 (8), 1382–87; Reactions of hydrazones and azines with metal salts 4. Reactions of azines of aldehydes and ketones with cupric salts. Russ. Chem. Bull. (Transl.) 1962, 11 (8), 1298–1302. DOI: 10.1007/BF00907973.
- ↑ King, Fiona; Nicholls, David Complex of titanium halides with acetone azine and its isomer 3,5,5-trimethyl-pyrazoline. Inorg. Chim. Acta 1978, 28, 55–58. DOI: 10.1016/S0020-1693(00)87413-7.
- ↑ Gilbert, E. C. J. Am. Chem. Soc. 1929, 51, 3394–3409.
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