Thiourea

  • Thiocarbamide
  • Thiourea
  • Sulfocarbamid
  • Thiourea
  • TH

White odorless solid

Fixed

1.41 g · cm -3 at 20 ° C.

182 ° C

Decomposition

Moderately soluble in water: 137 g · l-1 (20 ° C)

Attention

Not set

1750 mg · kg -1 ( LD50, rat, oral)

-89.1 KJ / mol

Template: Infobox chemical / molecular formula search available

Thiourea is a derivative of urea, whose oxygen atom is substituted by a sulfur atom.

Production and representation

Thiourea can be obtained from ammonium or calcium cyanamide:

Chemical Properties

Thiourea is an organic compound and a complexing agent. It occurs in two tautomeric forms. In aqueous solutions, the thione form dominates:

Crystal structure

Thiourea has an orthorhombic crystal structure with space group Pnma at room temperature. The carbon and the sulfur atom are located on a mirror plane so that the molecule has the point group symmetry CS. It is almost planar and the symmetry thus approximately C2v. On cooling the crystal or at high pressure caused by solid-solid phase transitions crystal structures with other symmetry.

Use

In 1993, the worldwide annual production was 10,000 tons. As a pure compound thiourea is mainly (25 % of production) used for the extraction of metals such as gold and silver from ores. Furthermore it is used as an adjuvant in the diazo paper (16 % of production) and as a catalyst for the isomerization of maleic acid to fumaric acid is used ( 12 % of production). As a reactant thiourea is used primarily for the production of thiourea dioxide ( 27.5 % of production). Other important applications are:

  • Additive in explosives ( explosive sludge)
  • Metal finishing ( copper refining )
  • Metal cleaning ( silver cleaning)
  • Modification of resins
  • Manufacture of additives for the textile and dyeing industry
  • Production of chemical intermediates

Biological Significance

Thiourea can inhibit the enzymes tyrosinase and urease.

Safety

Thiourea is carcinogenic category 3 ( possibly carcinogenic to humans) and teratogenic Category 3 (possibly teratogenic in humans). It can be very difficult to remove with normal wastewater treatment methods wastewater.

Derived compounds

  • Thiourea dioxide
  • Thioharnstoffnitrat ( CH5N3O3S )
  • Propylthiouracil
  • Propylene thiourea
  • Thiourea chelate
CAS registry number PubChem Dangerous Substances Directive (67/548/EEC) Selenourea CRC Handbook of Chemistry and Physics Digital Object Identifier
754379
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