How Thiourea is Produced and Its Role in Chemistry
An organosulfur compound is composed of carbon, nitrogen, hydrogen and sulfur atoms. Its chemical formula is SC(NH2)2. As the name and its composition suggest, thiourea is very much similar to urea. In thiourea, the oxygen atom of urea is displaced by the sulfur atom. Here you need to note that urea and thiourea are structurally similar but very different in physical and chemical properties. Thiourea is also known as thiocarbamide.
Thiourea, also known as thiocarbamide, is an organic molecule that is similar to urea (q.v.) but includes sulphur rather than oxygen; its chemical formula is CS(NH2)2, whereas ureas are CO(NH2)2. It, like urea, is made by inducing a chemically similar substance to undergo rearrangement, such as heating ammonium thiocyanate (NH4SCN). The addition of hydrogen sulphide to cyanamide is a more regularly utilised technique of production. Thiourea contains a lot of the same chemical features as urea, although it's not as widely used. The little amount of thiourea consumed is mostly used in photography as a fixing agent, in the production of thermosetting resin, as an insecticide, in the treatment of textiles, and as a starting ingredient for some colours and pharmaceuticals. At 182° C (360° F), thiourea crystallises as colourless crystals. It is poisonous, albeit the lethal dose has not been determined.
It is a bitter-tasting white water-soluble crystalline chemical that forms additional compounds with metal ions and is utilised in photographic fixing, rubber vulcanization, and synthetic resin production.
The sulphur analogue of urea is thiourea. Thiourea is employed because of its chemical resemblance to hydrogen sulphide. It plays a crucial function in the creation of heterocycles. It looks like white crystals that are flammable and emit unpleasant or poisonous odours when exposed to fire. It serves as a precursor to sulphide, allowing metal sulphides such as mercury sulphide to form.
Exposure to thiourea has negative health consequences and can lead to poisoning. It enters the body by inhalation of its aerosol and ingestion. Thiourea is known to produce skin sensitization and a variety of thyroid health problems when exposed to it repeatedly or for an extended period of time.
Thiourea is used in the manufacturing of flame retardant resins and vulcanization accelerators, among other things. Thiourea is utilised as an auxiliary agent in the diazo paper (light-sensitive photocopy paper) and nearly all other types of copy paper. This is also used to colour silver-gelatin photography prints.
Thiourea dioxide is a thiourea oxidising chemical that is stable in solid form and cold aqueous solution. It exhibits a moderate acidic reaction and only achieves maximal reduction capacity in an aqueous solution when heated to around 100 ° C.
The carbonyl group is the functional group in urea. A molecule has a functional group with a carbonyl group attached to two nitrogen atoms, or a functional group with a carbonyl group bound to two nitrogen atoms. The simplest member of this class is also known as urea.
When urea dissolves in water, it is neither acidic nor alkaline. This is utilised by the body in a variety of ways, the most essential of which is for nitrogen excretion. The liver modifies the urea cycle by combining two ammonia molecules (NH3) with a carbon dioxide molecule (CO2).
Drugs containing thiourea have non-competitive inhibition kinetics. All medications containing thiourea were classified as non-competitive inhibitors in enzyme inhibition kinetics, whereas the reference compounds (PTU and kojic acid) were classified as competitive inhibitors.
FAQs on Thiourea: Formula, Structure, and Uses Explained
1. What is thiourea and what is its chemical formula?
Thiourea, also known as thiocarbamide, is an organosulfur compound with the chemical formula CH₄N₂S. Structurally, it is similar to urea, but the oxygen atom is replaced by a sulfur atom. It typically appears as a white, crystalline solid and is soluble in water and polar organic solvents. Its molar mass is approximately 76.12 g/mol.
2. How is the structure of thiourea different from urea?
The primary structural difference between thiourea and urea lies in the atom double-bonded to the central carbon atom. While both molecules feature a central carbon bonded to two amine (-NH₂) groups, urea contains a carbonyl group (C=O), whereas thiourea contains a thiocarbonyl group (C=S). This substitution of sulfur for oxygen significantly impacts the molecule's properties, including bond length, polarity, and chemical reactivity, making thiourea a better complexing agent and reducing agent.
3. What are the main physical and chemical properties of thiourea?
Thiourea exhibits several distinct properties that are crucial for its applications. Key properties include:
Appearance: A lustrous, white crystalline solid at room temperature.
Solubility: It is soluble in water, hot ethanol, and ammonium thiocyanate solution but insoluble in non-polar solvents like ether.
Reactivity: It can act as a reducing agent and readily forms stable complexes with various metal ions, which is a basis for many of its uses.
Tautomerism: Thiourea can exist in tautomeric forms, primarily the thione form (C=S) and the thiol form (C-SH), which influences its reaction pathways.
4. What are the most common uses of thiourea in various industries?
Thiourea is a versatile chemical with a wide range of industrial applications. Some of its most common uses include:
Manufacturing: It is used in the production of flame-retardant resins and vulcanization accelerators for synthetic rubber.
Textile Industry: It acts as a reducing agent in dyeing and printing processes.
Photography and Copying: It is used as a fixing agent or auxiliary agent in diazo paper (light-sensitive copy paper) and to tone silver-gelatin photographic prints.
Metal Finishing: It is a component in solutions for cleaning and plating metals, including as a tarnish remover for silver and in electroplating baths.
Chemical Synthesis: It serves as a building block for synthesising certain dyes, pesticides, and pharmaceuticals.
5. How does thiourea work as a tarnish remover for silver?
Silver tarnish is primarily silver sulfide (Ag₂S), a compound that is very dark and insoluble in water. Thiourea is effective at removing this tarnish because it acts as a powerful complexing or sequestering agent. In an acidic solution, thiourea bonds strongly to the silver ions within the silver sulfide layer. This process forms a soluble silver-thiourea complex, which lifts the tarnish away from the object's surface and dissolves it into the solution, thereby restoring the silver's original shine.
6. Why is thiourea considered hazardous, and what precautions are necessary when handling it?
Thiourea is considered hazardous because it is a toxic and carcinogenic (cancer-causing) substance. Prolonged or significant exposure can interfere with the normal functioning of the thyroid gland, an effect known as goitrogenesis. Furthermore, when heated to decomposition, it releases highly toxic fumes of sulfur and nitrogen oxides. Due to these risks, strict safety precautions are necessary when handling thiourea, including using personal protective equipment (PPE) like gloves and safety glasses, ensuring adequate ventilation, and avoiding inhalation of its dust or fumes.
7. What is the functional group in thiourea and how does it influence its reactivity?
The key functional group in thiourea is the thiocarbonyl group (C=S) bonded to two amine groups. The presence of the sulfur atom is the main driver of its chemical reactivity. Compared to the oxygen atom in urea's carbonyl group (C=O), the sulfur atom is larger, less electronegative, and its double bond with carbon (C=S) is weaker and more easily polarized. This makes the sulfur atom in thiourea highly reactive, allowing it to easily participate in reactions, act as a reducing agent, and form strong, stable complexes with metal ions.
8. How is thiourea synthesized on an industrial scale?
On an industrial scale, thiourea is commonly produced through two primary methods. The traditional method involves the thermal isomerization of ammonium thiocyanate (NH₄SCN), where heating the compound causes it to rearrange into thiourea. A more modern and widely used method involves the reaction of hydrogen sulfide (H₂S) with calcium cyanamide (CaCN₂) in the presence of carbon dioxide. This process is often preferred for large-scale production due to its efficiency and the availability of the starting materials.
