Dimethylglyoxime - C<sub>4</sub>H<sub>8</sub>N<sub>2</sub>O<sub>2</sub>

What is Dimethylglyoxime?

Dimethylglyoxime is a white powder with the molecular formula C4H8N2O2. It is soluble in methanol or in sodium hydroxide solution. It is one of the first selective organic reagents applied in analytical chemistry. It is an extraordinary sensitive and specific reagent for nickel. Many derivatives of Dimethylglyoxime has been synthesized and proposed. Although commonly used as a reagent specific to nickel, Dimethylglyoxime actually allows the detection of other metal ions.

Other name – 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

Structure of Dimethylglyoxime

Physical Properties of Dimethylglyoxime – C4H8N2O2

Odour Odorless
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, white palladium come down as a yellow compound from dilute hydrochloric acid solutions. These are dried and weighed as stoichiometric compounds.

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