Dimethylglyoxime
Structural formula | ||||||||||||||||
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General | ||||||||||||||||
Surname | Dimethylglyoxime | |||||||||||||||
other names |
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Molecular formula | C 4 H 8 N 2 O 2 | |||||||||||||||
Brief description |
colorless, odorless powder |
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properties | ||||||||||||||||
Molar mass | 116.12 g mol −1 | |||||||||||||||
Physical state |
firmly |
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Melting point | ||||||||||||||||
solubility |
slightly soluble in water (0.6 g l −1 at 20 ° C) |
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safety instructions | ||||||||||||||||
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Toxicological data | ||||||||||||||||
Thermodynamic properties | ||||||||||||||||
ΔH f 0 |
−199.7 kJ / mol |
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As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . |
Dimethylglyoxime , also diacetyldioxime , is a dioxime and is used as a detection reagent ( Tschugajew reagent) for various heavy metal ions .
history
The complexing agent was first described in 1905 by Lev Alexandrovich Tschugajew .
Extraction and presentation
Dimethylglyoxime is obtained in a multi-stage reaction. Butanone (methyl ethyl ketone) is converted into diacetyl monoxime by nitrosation with ethyl nitrite . Without prior isolation, this reacts with sodium hydroxylamine-O-sulfonate to form dimethylglyoxime.
Course of the synthesis of dimethyldioxime, starting from butanone and ethyl nitrite.
properties
Dimethylglyoxime is a complexing agent that forms colored chelate complexes with heavy metal ions such as Ni 2+ , Fe 2+ , Co 2+ , Cu 2+ , Pt 2+ , Pd 2+ and Re 7+ . As a qualitative proof, the complexes can be precipitated under the appropriate conditions ( pH and temperature). Complexes of Co, Fe, Ni, Pd and Re are suitable for quantitative, photometric determination .
The complexes have the following colors:
- Nickel (II) complex: raspberry red
- Copper (II) complex: brown-red
- Iron (II) complex: red
- Cobalt (II) complex: purple
- Palladium (II) complex: yellow-yellowish
- Platinum (II) complex: brown and blue
- Lead (II) complex: white
- Bismuth (III) complex: intense yellow
The heat of decomposition determined by DSC is −230 kJ · mol −1 or −1980 kJ · kg −1 .
Nickel complex
In particular, the pink-red to raspberry-red, very poorly soluble bis (diacetylglyoximato) nickel (II) (nickel-dimethylglyoxime complex; [Ni (dmg) 2 ]) in ammoniacal solution serves as a qualitative nickel (II) test (see also nickel test ) and is used for quantitative determination, both via photometric and gravimetric methods, for nickel salts. The chelate compound has a square planar structure.
The color can still be detected at 0.015 µg nickel / ml. (Limit concentration of 1: 4 · 10 5 )
In the solid state, the complexes form stacks of molecules with a Ni – Ni distance of 325 pm.
Reagent
- 1% alcoholic solution of dimethyldioxime
Individual evidence
- ↑ a b c Entry on biacetyldioxime. In: Römpp Online . Georg Thieme Verlag, accessed on June 12, 2014.
- ↑ a b c d Entry on butanedione dioxime in the GESTIS substance database of the IFA , accessed on January 9, 2019(JavaScript required) .
- ↑ Entry on dimethylglyoxime in the ChemIDplus database of the United States National Library of Medicine (NLM) .
- ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-26.
- ↑ Lev Tschugaeff: About a new, sensitive reagent on nickel. In: Reports of the German Chemical Society. 1905, Vol. 38, No. 3, pp. 2520-2522, doi: 10.1002 / cber.19050380317 .
- ^ KH Slotta, KR Jacobi: Production of organic reagents in the analytical laboratory. III. Diacetyl dioxime . In: Journal for Analytical Chemistry . tape 83 , no. 1-2 , January 1931, pp. 1–5 , doi : 10.1007 / bf01361818 ( PDF ).
- ↑ Gerhard Jander: Jander⋅Blasius textbook of analytical and preparative inorganic chemistry , Hirzel, Stuttgart, 1985, pages 259, 359, 361st
- ↑ a b c G. Jander, H. Wendt: Textbook of analytical and preparative inorganic chemistry . 2nd Edition. S. Hirzel Verlag, Leipzig 1954, p. 108 f., 191 .
- ↑ Grewer, T .; Klais, O .: Exothermic decomposition - investigations of the characteristic material properties , VDI-Verlag, series "Humanisierung des Arbeitsleben", Volume 84, Düsseldorf 1988, ISBN 3-18-400855-X , p. 9.
- ^ Wittko Francke and Wolfgang Walter: Textbook of organic chemistry . S. Hirzel Verlag Stuttgart; 24. revised 2004 edition, ISBN 3-7776-1221-9 ; P. 342.
- ^ A b Wolfgang Werner: Qualitative inorganic analysis: for pharmacists and natural scientists Deutscher Apotheker Verlag; 4. completely rework. u. exp. Edition 2006; ISBN 3-8047-2264-4 ; P. 95.
- ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 1715.