Thiocyanate

As thiocyanates (also rhodanides obsolete), the salts and esters of volatile thiocyanic ( hydrogen thiocyanate acid) HSCN called. The name " thiocyanate " derives from the Greek rhodos for " red ", since iron (III ) thiocyanate has a deep red color. The salts can be prepared with sulfur easiest by melting the corresponding cyanides

Potassium thiocyanate is the best known salt and is used among other things for the detection of Fe 3 ions, the deep red colored iron (III ) thiocyanate (Fe ( SCN ) 3) is formed.

The thiocyanate ion ( NCS ) can coordinate as ligand in complexes, both via the nitrogen atom but also via the sulfur atom is attached to the central atom, and therefore in the spectrochemical series occurs twice. In its chemical behavior it resembles the halides and is therefore included in the group of pseudo-halides.

The human liver produces thiocyanate in the degradation of cyanides by the enzyme thiocyanate synthetase. Also from some foods, such as cabbage, can thiocyanates from the mustard oil glycosides contained therein, such as glucobrassicin, are enzymatically released. Since the thiocyanate ion prevents the iodine uptake in the thyroid, it may cause excessive consumption ( depending on the type 0.5 to several kg per day) of carbon to form a goiter ( "cabbage goiter ").

Thiocyanate is also produced as a metabolite in the degradation of tobacco products in the body. About this way tobacco consumption among individuals can be demonstrated.

Organic chemistry

The esters of R-S -C ≡ N (R = organic radical, such as alkyl, aryl, etc.) of the thiocyanic acid are called Thiocyansäureester and constitutional isomers of Isothiocyansäureester RN = C = S. You smell garlic -like and are only slightly resistant.

Production

Thiocyansäureester can be synthesized from Bunte salts and sodium cyanide in a single stage.