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Dimethylglyoxime is a chemical compound with the formula C4H8N2O2. It is abbreviated as DMG and has a white powder-like appearance.
- Dimethylglyoxime is also referred to as 2,3-Butanedione Dioxide.
- Dimethylglyoxime is an extraordinarily sensitive and specific reagent for Nickel.
- It is less soluble in water than Sodium Hydroxide or Methanol.
- Dimethylglyoxime is one of the first selective organic reagents used in Analytical Chemistry.
- It has been possible to manufacture many of its derivatives.
- It aids in the detection of numerous other metal ions apart from Nickel.
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Key Terms: Dimethylglyoxime, Reagent, Sodium Hydroxide, Nickel, DMG, Metals, Palladium, Analytical Chemistry, Dimethylglyoximato Ligand
What is Dimethylglyoxime?
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Dimethylglyoxime is a white-colored powder-like chemical compound.
- It has the chemical formula C4H8N2O2.
- It is substantially less soluble in water but soluble in sodium hydroxide solution or methanol.
- It is also referred to as 2,3-Butanedione Dioxide and has the abbreviation DMG.
- DMG is commonly used as a reagent in analytical chemistry.
- Multiple derivatives of DMG have been synthesized to date.
- Dimethylglyoxime helps in the detection of various other metal ions apart from Nickel.
- The anionic form of Dimethylglyoxime is termed DMGH, and its neutral form is DMGH2 where H indicates hydrogen.
- DMGH2 is used to identify Nickel and Palladium and also acts as a bidentate ligand, that is, it has two donor arms.
Dimethylglyoxime
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| Relevant Concepts | ||
|---|---|---|
| Oximes | Dimethyl Sulfoxide | Coordination Compounds |
| Nomenclature of Coordination Compounds | Coordination Number | Organometallic Compounds |
Dimethylglyoxime Structure
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Dimethylglyoxime, abbreviated as DMG is a white-colored chemical that is substantially less soluble in water. The chemical formula of Dimethylglyoxime is C4H8N2O2, and it is also known as 2,3-Butanedione dioxide.
Dimethylglyoxime Structure is as follows:
Dimethylglyoxime Structure
Dimethylglyoximato Ligand
Dimethylglyoximato is a good example of an asymmetric ligand. Dimethylglyoximato has a charge of -1, making it an anionic ligand. Dimethylglyoximato ligand has two donor atoms and is a bidentate ligand. It coordinates through 2 N atoms.
Properties of Dimethylglyoxime
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Dimethylglyoxime is a reagent for nickel that is incredibly sensitive and focused. Many derivatives of Dimethylglyoxime have already been synthesized and produced. Dimethylglyoxime, though frequently employed as a reagent specific to nickel, also enables the detection of other metal ions.
The properties of Dimethylglyoxime are as follows:
| Properties of Dimethylglyoxime | |
|---|---|
| Chemical Formula | C4H8N2O2 |
| Density | 1.37 g/cm3 |
| Molecular Weight/ Molar Mass | 116.12 g/mol |
| Boiling Point | Not Determined |
| Melting Point | 240 to 241 °C |
Physical Properties of Dimethylglyoxime
The physical properties of Dimethylglyoxime are as follows:
| Physical Properties of Dimethylglyoxime | |
|---|---|
| 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
Given below are the chemical properties of Dimethylglyoxime:
(I) Dimethylglyoxime and nickel ions react to generate an insoluble crimson precipitate of nickel dimethylglyoxime.
| Ni2+ + 2C4H8N2O2 \(\to\) Ni(C4H7N2O2)2\(\downarrow\) (Red Precipitate) + 2H+ |
(II) A complex combination of iron, ammonium sulfate, and water is created when dimethylglyoxime interacts with ferrous sulfate and ammonium hydroxide.
| FeSO4 + 2NH4OH + 2C4H8N2O2 \(\to\) Fe(C4H7N2O2)2 + (NH4)2SO4 + 2H2O |
Uses of Dimethylglyoxime
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The important uses of Dimethylglyoxime are as follows:
- It is widely used in analytical chemistry as a photometric reagent, a reagent for detecting metal ions, and a reagent for selectively precipitating nickel, palladium, and platinum ions, among other metal ions.
- Dimethylglyoxime is used as a test for nickel release in jewelry and other items that come into direct touch with the skin.
- Dimethylglyoxime test is now commercially available in pharmacies or chemist stores in several nations.
- It is used as a specific precipitant for the precipitation of nickel and palladium.
- White palladium precipitates as a yellow product from diluted hydrochloric acid solutions, whereas nickel comes down as a brilliant red, voluminous substance from the ammoniacal solution.
- These are weighed as stoichiometric compounds after being dried.
Dimethylglyoxime Health Hazards
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Dimethylglyoxime can cause several health effects in case of unregulated exposure. Given below are a few potential health hazards of DMG:
- DMG can cause eye and skin irritation.
- Ingestion of DMG can be harmful causing irritation in the digestive tract.
- It can also cause irritation in the respiratory tract as well as mucous membranes.
Due to its flammable nature, dimethylglyoxime is a direct fire hazard as it may be ignited by sparks alone. If it leads to fire, highly toxic gases may be emitted with combustion or thermal decomposition.
Things to Remember
- Dimethylglyoxime is a white-colored powder-like compound with the chemical formula C4H8N2O2.
- It is abbreviated as DMG, DMGH in anionic form, and DMGH2 in the neutral form where H denotes Hydrogen.
- Dimethylglyoxime is an odorless, colorless white powdered substance, slightly soluble in water and a weak chelating agent.
- It is used as a selective precipitating reagent, detecting reagent, and photometric reagent for nickel, and palladium in Analytical Chemistry.
- It also helps in the detection of various other metal ions other than Nickel.
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Previous Year Questions
- Red precipitate is obtained when ethanol solution of dimethylglyoxime… (NEET - 2012)
- In basic medium the amount of Ni2+ in a solution can be… (WBJEE - 2013)
- The structure and hybridisation of… (NEET - 1996)
- The total number of possible isomers for the complex… (NEET - 1998)
- Among the following complexes, the one which shows… (NEET - 2014)
- Correct increasing order for the wavelengths of absorption in… (NEET - 2017)
- Which of the following carbonyls will have the strongest… (NEET - 2011)
- Which compound is zero valent metal complex… (KCET - 2005)
- A ligand can also be regarded as… (KCET - 2008)
- In which of the following complex ion, the central metal ion is in a… (KCET - 2006)
Sample Questions
Ques. What are the properties of Dimethylglyoxime? (3 Marks)
Ans. The properties of Dimethylglyoxime are as follows:
- DMG is a translucent, crystalline reagent that is water-insoluble but soluble in alcohol, acetone, and ether.
- Its melting point ranges from 238 to 241 °C.
- Its molecular weight is 116.12.
- It has no smell at all, i.e. it is odorless.
- Colored precipitates are produced by their reaction with metal ions, including vivid red precipitate with nickel and blue precipitate with copper, among others.
Ques. State the harmful health effects of Dimethylglyoxime. (3 Marks)
Ans. The harmful health effects of Dimethylglyoxime are as follows:
- Dimethylglyoxime can lead to eye and skin irritation
- Ingestion of Dimethylglyoxime can also cause irritation in the digestive tract
- Inhalation of Dimethylglyoxime can cause irritation in the respiratory tract as well as mucous membranes.
Ques. What is the purpose of Dimethylglyoxime? (3 Marks)
Ans. Dimethylglyoxime is widely utilized in Analytical Chemistry for the following purposes:
- As a Photometric Reagent
- Reagent for Detecting Metal Ions
- Reagent for Selectively Precipitating Nickel, Palladium, and Platinum Ions, among other metal ions.
Ques. Why is Dimethylglyoxime not water-soluble? (3 Marks)
Ans. Dimethylglyoxime has the chemical formula C4H8N2O2 and is abbreviated as DMG. The anionic form of Dimethylglyoxime is DMGH, and its neutral form is DMGH2 where H refers to hydrogen. It is often insoluble because the combination has no charges that would allow polar water molecules to bind to and solvate the ion. Thus, it is not soluble in water.
Ques. What function does DMG perform in Analytical Chemistry? (3 Marks)
Ans. Dimethylglyoxime (DMG) is an analytical reagent that is used to precipitate Nickel from its aqueous solution. Although the approach is quite effective for Ni recovery in terms of selectivity and completeness, it is not frequently used in industry. The failure of the reagent is blamed on Calcination as the cause.
Ques. What is Dimethylglyoxime Chemical Formula? (1 Mark)
Ans. Dimethylglyoxime Chemical Formula is C4H8N2O2. The formula is CH3C(NOH)C(NOH)CH3 when expanded. Dimethylglyoxime is also known as 2,3-butanedione dioxide.
Ques. What type of ligand is DMG? (1 Mark)
Ans. Dimethylglyoxime is classified as a bidentate ligand chelating large amounts of metals. Only two DMG molecules per metal center are required because Ni(dmg)22+ has a square-planar geometry.
Ques. Why is Dimethylglyoxime a Specific Reagent? (2 Marks)
Ans. Dimethylglyoxime is a white chemical powder. It is soluble in sodium hydroxide solution or methanol but only to a very limited extent in water. It is among the earliest organic selective reagents used in analytical chemistry. It is a highly sensitive and focused reagent for the metal Nickel.
Ques. How is Dimethylglyoxime produced? (3 Marks)
Ans. Biacetyl Monoxime is subjected to the following chemical reactions to produce Dimethylglyoxime:
- Hydrochloric Acid on Biacetyl Monoxime
- Hydroxylamine on Biacetyl
- Hydroxylamine on Biacetyl Monoxime
- Sodium Hydroxylamine Monosulfonate on Biacetyl Monoxime
Ques. What is Dimethylglyoxime Test? (2 Marks)
Ans. Dimethylglyoxime Test is used to detect the existence of a red precipitate. 1% dimethylglyoxime in an alcoholic solution and 10% ammonium hydroxide solution is added to a test item, and the dimethylglyoxime test helps to detect the existence of the red precipitate.
Ques. What function does DMG serve in a Gravimetric Analysis? (2 Marks)
Ans. Dimethylglyoxime (DMG) is only marginally soluble in water (0.063 g in 100 mL at 25°C), thus, an alcoholic solution of DMG is used as the precipitating reagent. Therefore, it is essential to avoid adding an excessive amount of the reagent because it would crystallize out with the chelate.
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