Dithiooxamide

Description

Dithiooxamide, originally known as rubeanic acid, is a deep red crystalline solid with a decomposition temperature of ≈200 oC. It is a chelating agent for the detecting determining copper, cobalt, and nickel. It is also used to stabilize ascorbic acid in acidic solutions.
In early 2015, H. Firouzabadi, N. Iranpoor, and co-workers at Shiraz University (Iran) discovered that dithiooxamide can be used as a thiolating agent. Because it is stable, odorless, and commercially available, it is an excellent alternative to thiol reagents, which are foul-smelling and often require harsh reaction conditions. It reacts with alkyl or benzyl halides in base at 35 oC to form sulfides. With aryl halides, the reaction is run at 120 oC with a catalyst

Chemical properties

orange to brown crystalline powder

The Uses of Dithiooxamide

Dithiooxamide acts as a chelating agent and used in the determination of copper(II), nickel(II) and cobalt(II). It is used as a building block in the synthesis of cyclen. It is involved in the preparation of thiazolothiazole-linked porous organic polymers and N,N'-disubstituted dithiooxamides. It is also employed as a modifier to prepare the modified glassy carbon electrode which is used to investigate the electrochemical properties of quercetin, an important flavonoid derivative. Further, it is involved in the preparation of chelating resin with formaldehyde, which finds application in separation and concentration of silver ions.

The Uses of Dithiooxamide

As a reagent for copper, cobalt, and nickel. As a stabilizer of ascorbic acid solutions: Smoczkiewicz, Grochmalicka, Nature 192, 16 (1961).

The Uses of Dithiooxamide

Rubeanic acid may be used for the quantitative precipitation of copper, nickel and cobalt. The copper complex is dark green, the cobalt brownish-red and the nickel violet. All these complexes are chelates of outstanding stability, and this, together with their vivid Colours, affords the reaction great analytical sensitivity.
The copper complex is the most stable of the three; it can be precipitated even from mild mineral acidic solution, while precipitation of the corresponding cobalt and nickel complexes requires buffered media. On the other hand, palladium, platinum and silver react with rubeanic acid to give precipitates in strongly acidic solution. It should be mentioned, however, that in the case of platinum and some other metals (zinc, cadmium, silver, lead, mercury) the product is the corresponding sulfide rather than the rubeanate complex.
Rubeanic acid reacts with ruthenium to give a blue water-soluble complex ion, which is utilized for the spectrophotometric determination of ruthenium. Rubeanic acid has similarly been used for the spectrophotometric determination of osmium.
It has also proved suitable for the solvent extraction separation and determination of thallium. It has been found that thallium exists in the organic phase in the form of a complex of composition Tl/dto/Hdto, where dto represents the rubeanate anion with one negative charge.

General Description

Dithiooxamide is reported to form complexes with Ni(II).

Safety Profile

Poison by ingestion, intraperitoneal, and intravenous routes. When heated to decomposition it emits very toxic fumes of NOx and SOx

Purification Methods

Crystallise dithiooxamide from EtOH and sublime it at high vacuum. [Beilstein 2 IV 1871.]