Thiocyanogen
Encyclopedia
Thiocyanogen,2, is a pseudohalogen
derived from the pseudohalide thiocyanate
, [SCN]−. This hexatomic compound exhibits C2 point group symmetry
and has the connectivity NCS-SCN. The oxidation ability is greater than bromine. It reacts with water:
(SCN)2 + H2O → HSCN + HSCNO
Thiocyanogen was originally prepared by the reaction of iodine
with a suspension of silver thiocyanate in diethyl ether
, but this reaction suffers from competing equilibria
attributed to the weak oxidizing power of iodine. An improved method for generating thiocyanogen entails oxidation of plumbous thiocyanate, which precipitates when aqueous solutions of lead(II) nitrate
and sodium thiocyanate
are combined. A suspension of anhydrous Pb(SCN)2 is treated with bromine
in glacial acetic acid to afford a 0.1M solution of thiocyanogen that is stable for days.
Thiocyanogen adds to alkenes to give 1,2-bis(thiocyanato) compounds.
Pseudohalogen
Pseudo'halogen molecules are inorganic molecules of the general formsPs–Ps or Ps–X, where Ps is a pseudohalogen group such as cyanide, cyanate, thiocyanate and others, and X is a "true" halogen...
derived from the pseudohalide thiocyanate
Thiocyanate
Thiocyanate is the anion [SCN]−. It is the conjugate base of thiocyanic acid. Common derivatives include the colourless salts potassium thiocyanate and sodium thiocyanate. Organic compounds containing the functional group SCN are also called thiocyanates...
, [SCN]−. This hexatomic compound exhibits C2 point group symmetry
Symmetry group
The symmetry group of an object is the group of all isometries under which it is invariant with composition as the operation...
and has the connectivity NCS-SCN. The oxidation ability is greater than bromine. It reacts with water:
(SCN)2 + H2O → HSCN + HSCNO
Thiocyanogen was originally prepared by the reaction of iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
with a suspension of silver thiocyanate in diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...
, but this reaction suffers from competing equilibria
Dynamic equilibrium
A dynamic equilibrium exists once a reversible reaction ceases to change its ratio of reactants/products, but substances move between the chemicals at an equal rate, meaning there is no net change. It is a particular example of a system in a steady state...
attributed to the weak oxidizing power of iodine. An improved method for generating thiocyanogen entails oxidation of plumbous thiocyanate, which precipitates when aqueous solutions of lead(II) nitrate
Lead(II) nitrate
Lead nitrate is an inorganic compound with the chemical formula Pb2. It commonly occurs as a colourless crystal or white powder and, unlike most other lead salts, is soluble in water....
and sodium thiocyanate
Sodium thiocyanate
Sodium thiocyanate is the chemical compound with the formula NaSCN. This colorless deliquescent salt is one of the main sources of the thiocyanate anion. As such, it is used as a precursor for the synthesis of pharmaceuticals and other specialty chemicals...
are combined. A suspension of anhydrous Pb(SCN)2 is treated with bromine
Bromine
Bromine ") is a chemical element with the symbol Br, an atomic number of 35, and an atomic mass of 79.904. It is in the halogen element group. The element was isolated independently by two chemists, Carl Jacob Löwig and Antoine Jerome Balard, in 1825–1826...
in glacial acetic acid to afford a 0.1M solution of thiocyanogen that is stable for days.
- Pb(SCN)2 + Br2 → (SCN)2 + PbBr2
Thiocyanogen adds to alkenes to give 1,2-bis(thiocyanato) compounds.