1) Basic information of Thiourea:
CAS No.: 62-56-6
Molecular Weight: 76.13
Synonyms: 2-Thiourea; Isothiourea; sulfocarbamide; sulfouren; sulourea; Thiocarbamide; Thiurea; THU; thio arbamid; sulphourea; carbamoylsulfamic acid
Density: 1.326 g/cm3
Melting Point: 171 °C
Boiling Point: 186.836 °C at 760 mmHg
Flash Point: 66.796 °C
Solubility: 13.6 g/100 mL (20 °C) in water
Appearance: white crystals or powder
Character: white glossy crystal, bitter taste, soluble in water and alcohol
Packing: polypropylene bag, 25kg/bag net
Storage information: Store in Cool and dry .place, keep away from strong light, high temperature
Usage: Used in the manufacture of sulfonamide, dye, resin, molding powder and so on, also used as rubber vulcanization accelerator, metallic minerals flotation agent and so on
2) Introduction of Thiourea:
Thiourea, also called thiocarbamide, an organic compound that resembles urea but contains sulfur instead of oxygen; i.e., the molecular formula is CS(NH2)2, while that of urea is CO(NH2)2. Like urea, it can be prepared by causing a compound with the same chemical composition to undergo rearrangement, as by heating ammonium thiocyanate (NH4SCN). A method of preparation more commonly used consists of the addition of hydrogen sulfide to cyanamide. Thiourea exhibits many of the chemical properties of urea, but it has little commercial application. The small quantity of thiourea consumed is utilized primarily in photography as a fixing agent, in the manufacture of a thermosetting resin, as an insecticide, as a textile-treating agent, and as starting material for certain dyes and drugs. Thiourea forms as colourless crystals melting at 182° C (360° F). It is toxic, although the fatal dosage is not well established.
3) Specification of Thiourea are:
Loss on heating
4) Preparation of Thiourea :
Numerous methods have already been proposed for the manufacture of thiourea by the treatment of an alkaline earth metal salt of cyanamide, such as calcium cyanamide, in the presence or absence of water with hydrogen sulfide or an alkaline earth metal sulfide, as calcium or barium sulfide and an agent such as carbonic acid, phosphoric acid, sulfuric acid or the like which decompose to form hydrogen sulfide and an insoluble alkaline earth metal salt. The reaction has been conducted at elevated and at ordinary temperatures and with or without the application of pressure.
Its preparation methods is barium sulfide reaction with sulfuric acid or hydrochloric acid, hydrogen sulfide gas by lime milk, negative pressure absorbing hydrogen sulfide was calcium solution reacts with calcium cyanamide, sulfur, calcium hydroxide and calcium cyanamide mole ratio is 1:5, under stirring constantly, the reaction temperature for 80 + 5 ℃, reaction time is 3 h, the negative pressure filter, the thiourea can generate liquid, then through evaporation, filtration, cooling, crystallization, a quick crystal thiourea, centrifugal dehydration for a quick finished products.
Reaction equation, such as: BaS + - H2SO4, BaSO4 + H2S
H2s + Ca (OH) 2 and Ca 2 + 2 h2o (SH)
5) Uses of Thiourea:
l 1. Producing thiourea dioxide, replacing sodium hydrosulfite
l 2. Used as flotation agent in gold mine
l 3. Used as intermediate of thiazole and drugs inhibiting thyroid disease
l 4. Used as intermediate of pesticide
l 5. Used as bleaching agent, coloring agent and antioxidant in textile industry
l 6. Used in photography, electroplating etc.
6）Analytical methods of Thiourea
Other industrial uses of thiourea include production of flame retardant resins, and vulcanization accelerators.
Thiourea is used as an auxiliary agent in diazo paper, light-sensitive photocopy paper and almost all other types of copy paper.
It is also used to tone silver-gelatin photographic prints.
The determination of thiourea in workplace air can be carried out by adsorption on a glass fibre filter, filterelution with water in an ultrasonic bath, C18 reversedphase HPLC with water as the mobile phase, and UV detection at 245 nm. The detection limit is 0.4 μg thiourea/litre sample solution; a recovery rate of 106 ±6% is given.
This method can also be applied to the detection of thiourea in water. The detection limit is 0.1 mg/litre
water. Thiourea concentrations above 10 mg/litre have to be diluted before analysis; solutions with very low
concentrations of the chemical can be concentrated in a rotary evaporator.
7) Effects on humans of Thiourea
There are reports on disorders of workers coming into contact with thiourea during the course of, for example, maintenance of machinery or packing, without providing any details as to exposure levels. The symptoms observed were typical of hypothyroidism, as
evidenced by facial oedema, hypotonia, bradycardia,electrocardiograph alterations associated with reduced basal metabolism, constipation, flatulence, polyuria, and granulocytopenia, accompanied by lymphocytosis and monocytosis. The first perturbations of the blood count were observed after 5.6 months of exposure, and the highest incidence of the symptoms was evident in those workers who
had been in contact with the chemical for 5.15 years. Indications of reduced thyroid function were observed in a Russian study of workers employed in thiourea manufacture.
8)A tunable library of substituted thiourea precursors to metal sulfide nanocrystals
Controlling the size of colloidal nanocrystals is essential to optimizing their performance in optoelectronic devices,
catalysis, and imaging applications. Traditional synthetic methods control size by terminating the growth, an approach
that limits the reaction yield and causes batch-to-batch variability. Herein we report a library of thioureas whose
substitution pattern tunes their conversion reactivity over more than five orders of magnitude and demonstrate that faster
thiourea conversion kinetics increases the extent of crystal nucleation. Tunable kinetics thereby allows the nanocrystal
concentration to be adjusted and a desired crystal size to be prepared at full conversion. Controlled precursor reactivity
and quantitative conversion improve the batch-to-batch consistency of the final nanocrystal size at industrially relevant
9) Related images of Thiourea