Dimethylglyoxime

Dimethylglyoxime

Names
IUPAC name Butane-2,3-dione dioxime
Other names Dimethylglyoxime Diacetyl dioxime Chugaev's Reagent
Identifiers
CAS Number	95-45-4 Y
3D model (Jmol)	Interactive image
ChemSpider	10606175 Y
ECHA InfoCard	100.002.201
RTECS number	EK2975000
UNII	2971MFT1KY Y
InChI InChI=1S/C4H8N2O2/c1-3(5-7)4(2)6-8/h7-8H,1-2H3/b5-3-,6-4+ Y Key: JGUQDUKBUKFFRO-CIIODKQPSA-N Y InChI=1/C4H8N2O2/c1-3(5-7)4(2)6-8/h7-8H,1-2H3/b5-3-,6-4+ Key: JGUQDUKBUKFFRO-CIIODKQPBA
SMILES C\C(=N\O)\C(\C)=N\O
Properties
Chemical formula	C4H8N2O2
Molar mass	116.12 g·mol−1
Appearance	White/Off White Powder
Density	1.37 g/cm3
Melting point	240 to 241 °C (464 to 466 °F; 513 to 514 K)
Boiling point	decomposes
Solubility in water	low
Structure
Dipole moment	0
Hazards
Main hazards	Toxic, Skin/Eye Irritant
Safety data sheet	External MSDS
R-phrases	R20/22
S-phrases	R22, R36/37
NFPA 704	2
Related compounds
Related compounds	Hydroxylamine salicylaldoxime
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Dimethylglyoxime is a chemical compound described by the formula CH₃C(NOH)C(NOH)CH₃. Its abbreviation is dmgH₂ for neutral form, and dmgH for anionic form, where H stands for hydrogen. This colourless solid is the dioxime derivative of the diketone butane-2,3-dione (also known as diacetyl). DmgH₂ is used in the analysis of palladium or nickel. Its coordination complexes are of theoretical interest as models for enzymes and as catalysts. Many related ligands can be prepared from other diketones, e.g. benzil.

Dimethylglyoxime can be prepared from butanone first by reaction with ethyl nitrite followed by sodium hydroxylamine monosulfonate:

Dimethylglyoxime is used as a chelating agent in the gravimetric analysis of nickel:

The use of DMG as a reagent to detect nickel was discovered by L. A. Chugaev in 1905. For qualitative analysis, dmgH₂ is often used as a solution in ethanol. It is the conjugate base, not dmgH₂ itself, that forms the complexes. Furthermore, a pair of dmgH⁻ ligands are joined through hydrogen bonds to give a macrocyclic ligand. 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 so precipitates from solution. This method is used for the gravimetric determination of nickel, e.g. in ores.

The nitrogen atoms in dmgH₂ and its complexes are sp² hybridized. Because of the planarity of the resulting ligand, the macrocycle [dmgH]₂²⁻ resembles some biologically important macrocyclic ligands, as found for example in vitamin B12 and myoglobin. A well known family of model complexes, the cobaloximes, have the formula CoR(dmgH)₂L, where R is an alkyl group and L is typically pyridine. In such complexes, L and R occupy “axial” positions on the cobalt, perpendicular to the plane of the (dmgH)₂. One of the examples of cobaloxime is chloro(pyridine)cobaloxime.