Dimethylglyoxime
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| Dimethylglyoxime | |
|---|---|
| Image:Dimethylglyoxime.png | |
| General | |
| Systematic name | 2,3-Butanedione Dioxime |
| Other names | Dimethylglyoxime, Diacetyl dioxime, Chugaev's Reagent |
| Molecular formula | C4H8N2O2 |
| Molar mass | 116.1194 g/mol |
| Appearance | White/Off White Powder |
| CAS number | [95-45-4] [1] |
| Properties | |
| Density and phase | 1.37 g/cm3 |
| Solubility in water | insoluble |
| Melting point | 240 - 241°C (513.15 K) |
| Boiling point | N/A |
| Structure | |
| trans, symmetric | |
| Dipole moment | |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | Toxic, Skin/Eye Irritant |
| NFPA 704 | |
| Flash point | |
| R/S statement | R: 20/22 S: 22-36/37 |
| RTECS number | EK2975000 |
| Supplementary data page | |
| Structure and properties | n, εr, etc. |
| Thermodynamic data | ΔHsub 96.8kJ/mol |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Other anions | |
| Other cations | |
| Related compounds | Hydroxylamine |
| Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references | |
Dimethylglyoxime, C4H8N2O2, is an oxime derivative of butanedione. It is a compound used in analysis as a precipitant for palladium or nickel. A distictive red precipitate is formed in the presence of the nickel(II) cation. It is often prepared as a solution in ethanol. Synonyms include 2,3-butanedionedioxime, 2,3-diisonitrosobutane and diacetyldioxime.
Dimethylglyoxime is synthesized by the reaction of diacetyl and hydroxylamine:
For laboratory use dimethylglyoxime is typically not made, but purchased.
Dimethylglyoxime is useful as a ligand for transition metals. In particular the conjugate base dmgH- forms planar macrocyclic ligands where the two subunits are joined through hydrogen bonds. The most famous complex is the bright red Ni(dmgH)2, formed by treatment of Ni(II) sources with dmgH2. This planar complex is very poorly soluble and is used for the gravimetric determination of nickel, e.g. in ores.
The nitrogen groups are sp2 hybridized rather than the typical sp3. In this regard [dmgH-]2 resembles some biologically important macrocyclic ligands, as found for example in vitamin B12. A typical model complex, also called cobaloximes, is Co[CH[CH3)2](dmgH)2(py) In this complex, aside from the two dmgH- ligands, pyridine and the isopropyl groups occupy the axial positions, perpendicular to the (dmgH)2 plane.
[edit] References
↑ [Girolami, G.; Rauchfuss, T.; Angelici, R. Synthesis and Technique in Inorganic Chemistry: A Laboratory Manual. 3rd Ed, 1999, pp. 213-215.]
[edit] External links
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