月: 2023年1月

What Is Trifluoroacetic Acid?

Trifluoroacetic acid (TFA) is a colorless liquid at room temperature and a type of carboxylic acid, with the chemical formula CF3COOH. It is commonly abbreviated as TFA and is known as one of the strongest organic acids, second only to trifluoromethanesulfonic acid (TFSA).

First synthesized in 1922, TFA has become an important chemical in organic chemistry, with a global demand estimated at several hundred tons per year due to its distinctive properties.

Uses of Trifluoroacetic Acid

Trifluoroacetic acid is widely used in organic synthesis both as a raw material and as a preparation solution. In the pharmaceutical and agrochemical industries, it is highly valued, particularly as an intermediate for herbicides. It also serves as a protecting group for amino acids in pharmaceutical manufacturing.

Additionally, TFA is used in the production of anhydrous trifluoroacetic acid and trifluoroacetic acid esters.

In other industrial applications, TFA acts as an acid catalyst for various addition, esterification, and condensation reactions. It is also utilized in the manufacture of electronic materials, and as a solvent due to its unique chemical properties.

What Is Tellurium?

Tellurium, with atomic number 52, belongs to group 16 of the periodic table.

This nonmetallic element, symbolized as Te, has an atomic weight of 127.60 and exhibits isotopes ranging from mass numbers 105 to 132. Among these, eight are stable while the remainder are radioactive.

Classified under various safety laws, tellurium, and its compounds pose toxicity risks to humans.

Uses of Tellurium

Tellurium serves as an alloy additive in steel and other acid-resistant alloys to enhance workability and sulfuric acid resistance. Its compounds find uses in colorants for glass and ceramics, oxidizers, and thermoelectric elements, notably in thermocouples for electronic refrigeration systems. High-purity intermetallic Se-Te compounds are utilized in photosensitive drums for dry copying, offering high recovery and reuse rates.

Moreover, adding 0.01-1.0% metallic tellurium to steel improves its free-cutting features, toughness, and corrosion resistance, making such steel ideal for automotive and precision machine parts.

Properties of Tellurium

While many tellurium compounds emit a garlic-like odor, elemental tellurium is odorless. It has a melting point of 449.51°C, a boiling point of 988°C, and a specific gravity of 6.232. Chemically akin to sulfur and selenium, it burns in air with a blue-green flame to form tellurium dioxide (TeO₂) and reacts violently with halogens. Tellurium exhibits oxidation states of 6, 5, 4, 2, and -2 and forms a weakly acidic oxide.

Structure of Tellurium

Tellurium’s metallic form is a silvery-white crystal with a hexagonal structure, and its electron configuration is [Kr] 4d¹⁰ 5s² 5p⁴. It occurs naturally in various minerals, both as elemental tellurium and in compounds with gold, silver, copper, and lead.

Other Information on Tellurium

1. Production of Tellurium

Although tellurium’s environmental presence is minimal, it is primarily obtained from sulfide ores as tellurides and in minor quantities in gold and silver. Leading reserves are found in the United States, Peru, and Canada, with major producers being Canada, Belgium, the United States, Peru, and Japan, accounting for 82.3% of global production.

In Japan, tellurium is sourced from the Kawazu Mine in Shizuoka and the Tezu Mine in Hokkaido. Industrially, it is derived from anode mud in copper and lead refining processes, treated with soda ash to produce soluble tellurium salts, and then isolated as telluric acid (TeO₂・nH₂O).

2. Tellurium Isotopes

Of the 30 known tellurium isotopes, naturally occurring ¹²⁸Te and ¹³⁰Te are radioactive, undergoing double beta decay, with ¹²⁸Te having the longest half-life of any radioactive isotope. A small fraction of ¹¹⁰Te decays to ¹⁰⁶Sn via alpha decay. Artificially, ¹³¹I can be produced from neutron capture of ¹³⁰Te.

3. Tellurium Toxicity

Both elemental tellurium and its compounds are toxic, metabolizing in the body to produce dimethyl telluride, which emits a garlic-like odor. Exposure to tellurium compounds can lead to symptoms such as loss of appetite, headaches, nausea, and difficulty breathing, among others. These can be mitigated by avoiding further exposure.

What Is Potassium Thiocyanate?

Potassium thiocyanate, chemical formula KSCN and CAS No. 333-20-0, is a colorless, odorless crystal known for its high solubility in water and organic solvents like alcohol and acetone. This compound is an important salt of the thiocyanate anion, utilized across various industries due to its unique chemical and physical characteristics.

Uses of Potassium Thiocyanate

It serves a critical role in detecting iron (III) ions through its distinctive red color reaction and is used in the production of thiourea, pharmaceuticals, and synthetic resins, and as an auxiliary agent in photography and textile processes. Additionally, its endothermic dissolution property makes it useful as a refrigerant, hypotensive agent, insecticide, and fungicide. It also acts as an analytical reagent in chemical analysis.

Properties of Potassium Thiocyanate

Deliquescent at room temperature, potassium thiocyanate has a melting point of 173°C and a boiling point of 500°C. It exhibits a relative density of 1.886 and forms a cold solution upon dissolution due to its endothermic reaction. When heated or mixed with oxidizing agents, it can decompose, producing toxic cyanide gas.

Other Information on Potassium Thiocyanate

1. Manufacturing Process

Produced by reacting ammonium thiocyanate with potassium hydroxide, or through the interaction of potassium cyanide with sulfur, potassium thiocyanate’s synthesis is straightforward, allowing for efficient production.

2. Reactions

Its reactions with trivalent iron ions and lead nitrate are particularly noteworthy for detection and conversion processes in synthetic chemistry. It also facilitates the transformation of acyl chloride into isothiocyanate and the production of carbonyl sulfide from ethylene carbonate.

3. Legal Information

While not heavily regulated by major laws, precautions are necessary when handling potassium thiocyanate to prevent exposure to its reactive and potentially hazardous properties.

4. Handling and Storage Precautions

Recommended safety measures include tight sealing, cool and dark storage conditions, the use of protective gear, and rigorous post-handling hygiene practices to mitigate any risks associated with its use.

What Is Ammonium Thiocyanate?

Ammonium thiocyanate, with the formula NH₄SCN and CAS No. 1762-95-4, is a colorless or white, odorless crystal that deliquesces. It’s an ammonium salt of thiocyanic acid, known for its role in various industrial and analytical applications.

Uses of Ammonium Thiocyanate

It’s utilized in the textile industry for dyeing and improving silk strength and as a raw material in pharmaceuticals, synthetic resins, and agriculture. Analytically, it serves in titrations and colorimetric analyses, notably for determining iron content in beverages and removing sulfur from coal combustion gases.

Properties of Ammonium Thiocyanate

This compound exhibits a melting point of 149°C and decomposes at 170°C. It’s soluble in water, ethanol, and acetone, reacting endothermically with water and exhibiting weak acidity in aqueous solutions.

Other Information on Ammonium Thiocyanate

1. Manufacturing Process

Produced by reacting carbon disulfide with aqueous ammonia, it forms through the decomposition of ammonium dithiocarbamate, releasing hydrogen sulfide in the process.

2. Reactions

Stable in air, ammonium thiocyanate can transform into thiourea upon heating. It reacts with alkaline solutions to form thiocyanate anions, interacts with metal ions to form colored complexes or precipitates, and decomposes at high temperatures to produce gases and thiocyanate residues.

3. Legal Information

It’s recognized as a hazardous substance under various safety laws, requiring careful handling.

4. Handling and Storage Precautions

Storage should be in a cool, dry, and dark environment, avoiding light and moisture. Protective measures are necessary when handling, especially to prevent contact with alkalis, and strong oxidizers, and to manage decomposition products safely.

What Is Ammonium Thioglycolate?

Ammonium thioglycolate is an organic compound, a salt of thioglycolic acid.

Its chemical formula is C2H7NO2S. As an ammonium salt of thioglycolate, it contains one mercapto group and one carboxyl group in its molecule. Commonly known as ammonium mercaptoacetate, ammonium thioglycolate, or ATG, its CAS number is 5421-46-5.

This compound has a molecular weight of 109.15 and is typically sold as an aqueous solution. It appears as a clear, colorless liquid at room temperature, with a characteristic sulfur or ammonia-like odor. Its density is 1.190 g/cm3.

For storage, it should be kept away from direct sunlight and high temperatures, and not mixed with strong oxidizers. Due to its potential to corrode metal, metal containers should be avoided. Under normal storage conditions, it is stable.

Ammonium thioglycolate is toxic if ingested and can cause allergic reactions upon skin contact. Handling should be done with care to avoid skin and eye exposure.

Uses of Ammonium Thioglycolate

This compound is widely used for breaking down proteins and as a reducing agent. Its applications include serving as a permanent wave agent, wool dyeing and straightening agent, PVC stabilizer, rust inhibitor, and metal surface treatment agent.

With a neutral pH (6.8 – 7.4), ammonium thioglycolate is safer than other organic solvents. It’s also less toxic compared to hydrochloric acid or sulfuric acid, common ingredients in rust removers. It is user-friendly as a rust remover, turning purple when reacting with red rust, which serves as a cleaning guide.

Principle of Ammonium Thioglycolate

As a reducing agent, ammonium thioglycolate is less hazardous than thioglycolic acid and is widely used.

In hair perming, it breaks down proteins by reducing disulfide bonds in keratin to mercapto groups. As a rust remover, it reduces iron rust to water-soluble iron thioglycolate, facilitating rust removal.

Its reducing action is also applied in synthetic chemistry, where it’s used to synthesize:

• Thiol-functionalized eggshell membranes for removing heavy metals from water.
• Cellulose-rhodamine B-methacrylamide (cellulose-RhBMA).

Types of Ammonium Thioglycolate

Ammonium thioglycolate is available as a chemical reagent in aqueous solutions of various concentrations, such as 45.0~55.0%, 50%, and 60%. It is packaged in volumes like 500mL, 1L, 25g, and 500g, typically in glass bottles, and can be stored at room temperature.

In industrial settings, it is also sold as a rust remover raw material in poly-drum packages of 24 kg or 250 kg. Additionally, it is a key ingredient in neutral rust remover detergents and perm solutions, with various products available from different manufacturers.

What Is Selenium?

Selenium, with symbol Se and atomic number 34, is a chalcogenic element that exists in several forms, ranging from a dark reddish-brown amorphous solid to metallic gray crystals. As an essential trace element, selenium plays a crucial role in human health, being part of the enzyme glutathione peroxidase, which has antioxidant properties.

Uses of Selenium

Selenium’s semiconducting and photoconductive properties are harnessed in rectifiers, photocopiers, and photovoltaic cells, though its use is limited by its toxicity. It also serves as a colorant, rubber additive, and dietary supplement, with its bioavailability influenced by soil selenium concentrations.

Properties of Selenium

Selenium displays various allotropes and transforms with temperature changes. It has a melting point of 170-217°C and a boiling point of 685°C. Selenium is commercially available in amorphous and crystalline forms, showing different physical characteristics based on preparation methods.

Other Information on Selenium

1. Selenium Manufacturing Process

Selenium is typically extracted from selenide in sulfide ores through copper refining. The process involves oxidizing selenium dioxide and reducing it to metallic selenium with sulfur dioxide.

2. Selenium Reactions

It reacts with oxygen, fluorine, and cyanide to form various compounds, showcasing its versatility in chemical reactions across different oxidation states.

3. Regulatory Information

Regulated under multiple laws for its poisonous nature and environmental impact, selenium usage requires stringent handling and labeling protocols.

4. Handling and Storage Precautions

Safe handling involves storing in cool, dark places, using protective gear, and avoiding contact with strong acids and oxidizers to mitigate health and safety risks.

What Is Cerium?

Cerium, with the symbol Ce and atomic number 58, is a silvery-white lanthanide and the most abundant rare earth element, found mainly in the minerals monazite and bastnasite. It exhibits valences of +2, +3, and +4, with the +4 state being more common in its compounds, which are notable for their ability to absorb ultraviolet light.

Uses of Cerium

Commercially, cerium is used in UV-blocking glass, glass polishes, and as an alloy in lighter flints. Its oxides enhance the performance of catalytic converters, and its compounds are used in fluorescent materials for LEDs and cathode ray tubes.

Properties of Cerium

Cerium is a reactive metal, easily oxidizing in air to form cerium oxide and spontaneously igniting at 160°C. It reacts with water to produce cerium (III) hydroxide and dissolves in acids, forming colorless Ce(III) ions. The metal’s melting point is 795°C, and its boiling point is 3,443°C.

Structure of Cerium

At room temperature, cerium adopts a face-centered cubic structure, shifting to a body-centered cubic form above 730°C, and possesses a hexagonal close-packed structure at lower temperatures. Its density near room temperature is 6.770 g/cm³.

Other Information on Cerium

1. Production of Cerium

Primarily refined from bastnasite and monazite, cerium production is concentrated in China, with significant reserves in the United States and India. Cerium compounds and metals are produced through various chemical and electrolytic processes.

2. Isotopes of Cerium

Cerium has four stable isotopes and numerous radioactive isotopes, the most abundant of which is ¹⁴⁰Ce. The isotopes ¹⁴⁴Ce, ¹³⁹Ce, and ¹⁴¹Ce are notable for their relatively longer half-lives among the radioactive varieties.

What Is Cesium?

Cesium, symbol Cs, atomic number 55, is a soft, yellowish-silvery alkali metal that becomes liquid near room temperature. Found in minerals like polsite and logisite, cesium reacts vigorously with water and oxidizes in the air, making it highly reactive. Cesium-137, a radioactive isotope, is a known byproduct of nuclear fission.

Uses of Cesium

Due to its ability to emit electrons under light, cesium is utilized in phototubes and strobe discharge tubes. Its applications extend to catalysts in industry, improving other metal oxide catalysts’ functions, and in the manufacturing of optical glass. Cesium compounds like cesium iodide and cesium fluoride are essential in radiation measurement and medical diagnostics due to their scintillation properties. Additionally, cesium’s precise electron transitions are utilized in atomic clocks for timekeeping.

Properties of Cesium

With a melting point of 28.5°C and a boiling point of 705°C, cesium is the softest element solid at room temperature. Its high reactivity includes spontaneous combustion in air and explosive reactions with water, showcasing a Mohs hardness of only 0.2.

Structure of Cesium

At room temperature, cesium exhibits a body-centered cubic lattice structure, transitioning to rhombohedral at varying temperatures and pressures. Its cubic α-Cs phase is the most stable under normal conditions.

Other Information on Cesium

1. Process of Cesium

Cesium is extracted from ores like porcite through acid or alkali decomposition or direct reduction. It can also be obtained from cesium compounds by reduction with calcium or barium, electrolysis of cesium cyanide, pyrolysis of cesium azide, or reaction with zirconium.

2. Legal Information

Cesium falls under various safety laws, highlighting its need for careful handling. 

3. Handling and Storage Precautions

Proper storage in a cool, dry, and well-ventilated area under an inert gas atmosphere is crucial. Protective gear is essential to prevent violent reactions with common substances and ensure safety during handling.

What Is Sodium Sulfonate?

Sodium Sulfonate, commonly referred to as LAS (Linear Alkylbenzene Sulfonates), encompasses compounds like sodium linear alkylbenzenesulfonate and sodium dodecylbenzenesulfonate. These compounds are predominantly used as surfactants in synthetic detergents.

Sodium linear alkylbenzenesulfonate appears as a white to light yellow crystalline powder. It is readily soluble in warm water and ethanol, and easily dissolves in water. Sodium dodecylbenzenesulfonate, on the other hand, is also a white crystalline powder but is specifically noted for its easy solubility in water.

Uses of Sodium Sulfonate

As a key ingredient in synthetic detergents, sodium sulfonate serves as an anionic surfactant. Detergents formulated with sodium linear alkylbenzene sulfonate are known for their stability against acids and hard water, alongside their potent cleaning properties. While both branched-chain (ABS) and linear-chain (LAS) sulfonates were historically used, the latter is now more prevalent due to its superior biodegradability.

In addition to its primary role in detergents, sodium dodecylbenzenesulfonate finds application as a wetting agent, emulsifier, and component in agrochemical formulations. Its versatility underlines its importance in various industrial and commercial products.

What Is Sulfonic Acid?

Sulfonic acid refers to a group of organic compounds characterized by the presence of a sulfonic group (SO3H) attached to the carbon skeleton. These acids are known for their hydrophilic nature, rendering them soluble in water, and their aqueous solutions exhibit high acidity.

Sulfonic acids can be classified based on their parent hydrocarbon structure into various types, including aliphatic, aromatic, and heterocyclic sulfonic acids. For instance, aliphatic sulfonic acids are synthesized by reacting alkanes with sulfur trioxide, whereas aromatic sulfonic acids are produced by sulfonating aromatic hydrocarbons with fuming sulfuric acid.

Uses of Sulfonic Acid

Sulfonic acids are versatile and are commonly used in the synthesis of various organic compounds, including dyes, surfactants, and pharmaceuticals. Some typical examples of sulfonic acid compounds and their applications are:

• Methanesulfonic Acid: Utilized in pharmaceutical salts and as an acid catalyst in dehydration-condensation reactions.
• Benzenesulfonic Acid: Employed as an acid catalyst, reagent, and in the production of besylates.
• p-Toluenesulfonic Acid: Serves as an acid catalyst and is involved in the synthesis of saccharin.
• Trifluoromethanesulfonic Acid: Notably more acidic than pure sulfuric acid, this is used primarily as an acid catalyst in various chemical reactions.

The diverse applications of sulfonic acids underscore their importance in chemical manufacturing and industrial processes.