Dimethylglyoxime - C4H8N2O2

What is Dimethylglyoxime?

Dimethylglyoxime is a white powder with the molecular formula C4H8N2O2.

Dimethylglyoxime is soluble in methanol or in sodium hydroxide solution. It is one of the first selective organic reagents applied in analytical chemistry.

Table of Contents

General Properties of Dimethylglyoxime – C4H8N2O2

Dimethylglyoxime is an extraordinarily sensitive and specific reagent for nickel. Many derivatives of Dimethylglyoxime have been synthesized and proposed. Although commonly used as a reagent specific to nickel, Dimethylglyoxime actually allows the detection of other metal ions.

Other names – 2,3-Butanedione, Biacetyl dioxime, dioxime, N-(3-hydroxyiminobutan-2-ylidene)hydroxylamine

C4H8N2O2 Dimethylglyoxime
Density 1.37 g/cm³
Molecular Weight/ Molar Mass 116.12 g/mol
Boiling Point Not determined
Melting Point 240 to 241 °C
Chemical Formula CH3C(NOH)C(NOH)CH3

Dimethylglyoxime Structure – C4H8N2O2

Dimethylglyoxime Structure

Dimethylglyoxime Structure – C4H8N2O2

Dimethylglyoximato Ligand

Dimethylglyoximato is an example of asymmetric ligand. The charge of dimethylglyoximato is -1 and so it is an anionic ligand. The number of donor atoms in dimethylglyoximato ligand is 2. It is a bidentate ligand. It coordinates through 2 N atoms.

Physical Properties of Dimethylglyoxime – C4H8N2O2

Odour Odourless
Appearance Off White Powder
Complexity 112
Dipole moment 0
Hydrogen Bond Donor 2
Solubility Insoluble in water, soluble in alcohol

Chemical Properties of Dimethylglyoxime – C4H8N2O2

  • Nickel cation reacts with dimethylglyoxime forms an insoluble red precipitate of nickel dimethylglyoxime.

Ni2+ + 2C4H8N2O2 → Ni(C4H7N2O2)2↓(red precipitate) + 2H+

  • Dimethylglyoxime reacts with ferrous sulphate and ammonium hydroxide forms a complex compound of iron and ammonium sulphate and water is formed.

FeSO4 + 2NH4OH + 2C4H8N2O2 → Fe(C4H7N2O2)2 + (NH4)2SO4 + 2H2O

Uses of Dimethylglyoxime – C4H8N2O2

  • Widely used in analytical chemistry as a selective precipitating reagent, detecting reagent and photometric reagent for nickel, palladium, platinum and some other metal ions.
  • Used as a test for nickel release and used for jewellery and for other objects that come in direct contact with the skin. In many countries, the dimethylglyoxime test is now commercially available in pharmacies or chemist shops.
  • Used as a specific precipitant for nickel and palladium. Nickel precipitates as a bright red voluminous compound from ammoniacal solution, and white palladium comes down as a yellow compound from dilute hydrochloric acid solutions. These are dried and weighed as stoichiometric compounds.

Frequently Asked Questions – FAQs


What is Dimethylglyoxime used for?

Dimethylglyoxime is used for the identification and quantification of nickel into the bright red compound of nickel bis(dimethylglyoximate)


Why is Dimethylglyoxime insoluble in water?

Ni(DMG)2 is a neutral complex the abbreviation is dmgH2 for neutral form, and dmgH for anionic form, where H stands for hydrogen that is usually insoluble since there are no charges on the compound to bind and solvate the ion by polar water molecules.


What type of ligand is DMG?

Dimethylglyoxime (dmg) is a bidentate ligand chelating large amounts of metals. Only two dmg molecules per metal centre are needed, because Ni(dmg)22 + has a square-planar geometry.


What is the role of DMG in analytical chemistry?

Dimethylglyoxime (DMG) is an analytical reagent used from its aqueous solution to precipitate Ni. The method is very effective in terms of selectivity and completeness for Ni recovery but is hardly industrially adopted. The cause is attributed to calcination to the failure of the reagent.


Is DMG Bidentate?

Dimethylglycine (dmg) is a bidentate ligand chelating large amounts of metals. Only two dmg molecules per metal centre are needed because Ni(dmg)22 + has a square-planar geometry.

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