Chemical Properties
white crystals or powder
Uses
Chaotropic agent; strong denaturant. Increases solubility and recovery of proteins
Uses
The product is wildly used in pharmaceutical industry, agricultural, chemicals, metallurgical industry, petroleum and so on. It is also main material for producing thiourea dioxide(CH1N2O2S).
Uses
Used in determination of bismuth.
Definition
ChEBI: The simplest member of the thiourea class, consisting of urea with the oxygen atom substituted by sulfur.
Uses
In animal glue liquifiers and silver tarnish removers. Photographic fixing agent and to remove stains from negatives; manufacture of resins; vulcanization accelerator; a reagent for bismuth, selenite ions.
General Description
White or off-white crystals or powder. Sinks and mixes with water.
Reactivity Profile
THIOUREA(62-56-6) is a white crystalline material or powder, toxic, carcinogenic. When heated to decomposition THIOUREA(62-56-6) emits very toxic fumes of oxides of sulfur and oxides of nitrogen. Violent exothermic polymerization reaction with acrylaldehyde (acrolein) [MCA SD-85, 1961], violent decomposition of the reaction product with hydrogen peroxide and nitric acid [Bjorklund G. H. et al., Trans. R. Soc. Can.,1950, 44, p. 28], spontaneous explosion upon grinding with potassium chlorate [Soothill, D., Safety Management, 1992, 8(6), p. 11].
Air & Water Reactions
Water soluble.
Health Hazard
Poisonous inhaled or swallowed. Irritating to skin; may cause allergic skin eruptions.
Potential Exposure
Thiourea is used as rubber antiozonant, toning agent; corrosion inhibitor; and in pharmaceutical manufacture; in the manufacture of photosensitive papers; flame-retardant textile sizes; boiler water treatment. It is also used in photography; pesticide manufacture; in textile chemicals.
First aid
Move victim to fresh air. Call 911 or emergency medical service. Give artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; give artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. For minor skin contact, avoid spreading material on unaffected skin. Keep victim warm and quiet. Effects of exposure (inhalation, ingestion or skin contact) to substance may be delayed. Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves. Medical observation is recommended for 24-48 hours after breathing overexposure, as pulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consider administering a drug or other inhalation therapy.
Shipping
UN2811 Toxic solids, organic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required. UN3077 Environmentally hazardous substances, solid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous hazardous material, Technical Name Required.
Incompatibilities
Dust may form explosive mixture with air. Reacts violently with acrolein, strong acids (nitric acid). Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides.
Waste Disposal
Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal.
Preparation
Thiourea is manufactured by heating ammonium thiocyanate at 140-145??C
for about 4 hours; equilibrium is established when about 25% of the
thiocyanate is converted to thiourea.Thiourea may also be prepared by the interaction of cyanamide and hydrogen sulphide:
Thiourea closely resembles urea in that reaction with formaldehyde gives
methylol derivatives and then resinous condensates which on continued
heating yield network structures. Thiourea-formaldehyde resins are slower
curing than urea-formaldehyde resins and the hardened products are more
brittle and more water-resistant. At one time thiourea-formaldehyde resins
were added to urea-formaldehyde resins to give mouldings and laminates
with improved water-resistance. These mixed resins have now been largely
superseded by melamine-formaldehyde resins which give products with better
resistance to heat.
Production Methods
Thiourea is formed by heating ammonium thiocyanate at 170 °C (338 °F). After about an hour, 25% conversion is achieved. With HCl, thiourea forms thiourea hydrochloride; with mercuric oxide, thiourea forms a salt; and with silver chloride, it forms a complex salt.
Hazard
A questionable carcinogen. May not be
used in food products (FDA); skin irritant (allergenic).
Fire Hazard
Noncombustible solid. There is no report of
any explosion resulting from reactions of
thiourea. Small amounts of thiourea in contact with acrolein may polymerize acrolein,
which is a highly exothermic reaction.
Agricultural Uses
Thiourea is a sulphur analogue of urea. It is a crystalline
and colorless solid which is relatively insoluble in water.
Thiourea, capable of breaking the dormancy of seeds, is
used to stimulate seed germination. Seeds are soaked for
less than 24 hours before planting.
Biochem/physiol Actions
Thiourea is a free radical scavenger of the peroxide radical. It was shown to inhibit lipid peroxidation and ultraviolet (UV)-induced crosslinking of collagen. Bud dormancy in plants can be inhibited by thiourea, which is used as a growth stimulator. It is also known to be used in the treatment of hyperthyroidism.
Carcinogenicity
Thiourea is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental
animals.
Purification Methods
Crystallise thiourea from absolute EtOH, MeOH, acetonitrile or water. Dry it under vacuum over H2SO4 at room temperature. [Beilstein 3 IV 342.]
