Thiourea dioxide
| Thiourea dioxide | ||
|---|---|---|
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| IUPAC name amino(imino)methanesulfinic acid | ||
| Other names Thiourea dioxide, DegaFAS, Reducing Agent F, Depilor, Formamidine Sulfinic Acid | ||
| Identifiers | ||
| CAS number | 1758-73-2  | |
| PubChem | 61274 | |
| Jmol-3D images | Image 1 | |
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| Properties | ||
| Molecular formula | CH4N2O2S | |
| Molar mass | 108.12 g mol−1 | |
| Appearance | White powder | |
| Melting point | 126 °C; 259 °F; 399 K | |
| Solubility in water | 3.0 g/100 mL | |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | ||
| Infobox references | ||
Thiourea dioxide or thiox is an organosulfur compound that is used in the textile industry.[1] It functions as a reducing agent.[2] Thiourea dioxide is not a dioxide, but instead is a derivative of a sulfinic acid (RS(O)(OH), hence the alternative name formamidine sulfinic acid.[3]
Synthesis
Thiourea dioxide is prepared by the oxidation of thiourea with hydrogen peroxide.[4]
- (NH2)2CS + 2H2O2 → (NH)(NH2)CSO2H + 2H2O
The mechanism of the oxidation has been examined.[5] The aqueous solution of Thiourea dioxide has a pH about 6.5 at which thiourea dioxide is hydrolized to urea and sulfoxylic acid. It has been found that at pH values lower that 2 thiourea and hydrogen peroxide react to form a disulfide species. It is therefore convenient to keep the pH between 3 to 5 and the temperature below 10 °C.[6] It can also be prepared by oxidation of thiourea with chlorine dioxide.[7] The quality of the product can be assessed by titration with indigo.[4]
Uses
Thiourea dioxide is used in reductive bleaching in textiles.[8] Thiourea dioxide has also been used for the reduction of aromatic nitroaldehydes and nitroketones to nitroalcohols.[9]
Structure
The structure of thiourea dioxide is related to that for thiourea. The N2CS core is approximately planar, but the sulfur is pyramidal. Selected bond lengths: S-C = 1.85, C-N = 1.31, and S-O = 1.49 Å.[3]
References
- ↑ Klaus Fischer et al. "Textile Auxiliaries" in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a26_227
- ↑ Milne, G. W. A. Dictionary, in Gardner's Commercially Important Chemicals: Synonyms, Trade Names, and Properties, John Wiley & Sons, Inc. 2005, Hoboken, NJ, USA. doi:10.1002/0471736627.ch1.
- ↑ 3.0 3.1 Sullivan, R. A. L.; Hargreaves, A. (1962). "The Crystal and Molecular Structure of Thiourea Dioxide". Acta Crystallografica 15 (7): 675–682. doi:10.1107/S0365110X62001851.
- ↑ 4.0 4.1 D. Schubart "Sulfinic Acids and Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry, 2012, Wiley-VCH, Weinheim. doi:10.1002/14356007.a25_461
- ↑ Michael Hoffmann, John O. Edwards. "Kinetics and Mechanism of the Oxidation of Thiourea and N,N'-dialkylthioureas by Hydrogen Peroxide" Inorganic Chemistry, 1977, volume 16, pp 3333-3338. doi:10.1021/ic50178a069
- ↑ US patent 2783272, James H. Young, "PRODUCTION OF FORMAMIDINE SULFINIC ACID", issued 1957-2-26
- ↑ Rábai, G., Wang, R. T. and Kustin, "Kinetics and mechanism of the oxidation of thiourea by chlorine dioxide" International Journal of Chemical Kinetics, 1993, volume 25: 53–62. doi:10.1002/kin.550250106.
- ↑ Hebeish, A., El-Rafie, M. H., Waly, A. and Moursi, A. Z. (1978). "Graft copolymerization of vinyl monomers onto modified cotton. IX. Hydrogen peroxide–thiourea dioxide redox system induced grafting of 2-methyl-5-vinylpyridine onto oxidized celluloses". Journal of Applied Polymer Science 22 (7): 1853–1866. doi:10.1002/app.1978.070220709.
- ↑ Sambher, S., Baskar, C., & Dhillon, R. S. (2009). "Chemoselective reduction of carbonyl groups of aromatic nitro carbonyl compounds to the corresponding nitroalcohols using thiourea dioxide". Arkivoc 10: 141–145. ISSN 1551-7012.