Dithizone

• 3 - ( phenylamino ) - 1 - phenylimino thiourea ( IUPAC)
• 1.5 Diphenylthiocarbazone

Blue-black crystalline powder

Fixed

165-168 ° C ( decomposition)

• Insoluble in water, slightly in ethanol
• Well in carbon tetrachloride and chloroform, soluble with green color

Attention

• 56 mg · kg -1 ( LD50, mouse, i.v.)
• > 500 mg · kg -1 (LD, rat, oral)

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Dithizone is a bidentate chelating agents, which is used as a sensitive reagent in the ( trace ) Analysis of heavy metals.

Dithizone was synthesized in 1878 by Emil Fischer in 1925 and introduced by Hellmuth Fischer as heavy metal ion reagent.

Representation

Dithizone is formed by the reaction of phenylhydrazine with carbon disulfide. The resulting intermediate Diphenylthiocarbazid dehydrated by heating in a methanolic potassium hydroxide solution for dithizone.

Properties

Dithizone forms complexes with heavy metal ions form stable complexes, which are insoluble in water but soluble in carbon tetrachloride. The solutions of this dithizonates possess a characteristic color:

They can be determined qualitatively and quantitatively on the basis of this coloring and the fixed stoichiometry on colorimetric or photometric means.

Based on the differences in solubility of metal ions and metal complexes is employed in the extractive dithizone titration. In this, the aqueous solution of the analyte is titrated with a standard solution of dithizone in chloroform.

Dithizion is temporarily diabetogenic, as this zinc complexes, which is required for the function of insulin.

Use

The Dithizonat formation serves as a very sensitive method for trace analytical determination of various heavy metal ions. The detection limit for lead is 4.10 to 8 g at a concentration limit of 250 1:1 000 The zinc is using an extractive enrichment at a dilution of 1:50 000 000, i.e., 1 ug in 50 ml of water. Some evidence achieve detection of 10 to 100 ppm.

Pictures

Dithizone, 0.025 % solution / suspension in 96% ethanol

Dithizone in ethanol 96%, strongly diluted