月: 2023年1月

What Is Tetrahydrofuran?

Tetrahydrofuran is a type of saturated five-membered heterocyclic compound with one oxygen atom in the ring.

It is also known as THF or oxolane. About 200,000 tons are produced annually, and the most widely used industrial production method is the acid-catalyzed dehydration of 1,4-butanediol.

Using the coordination properties of oxygen, it can be used as a ligand for Lewis acids and metal ions. Solutions such as BH₃-THF, a stable complex with borane, are commercially available.

Due to its low flash point of -14.5°C, it is designated as a hazardous substance.

Uses of Tetrahydrofuran

• Solvent for synthetic resins such as polyvinyl chloride resin and organic synthetic reaction solvents
• Solvent for coating synthetic leather, etc.
• Solvent for vinyl and epoxy adhesives
• Solvent for printing inks
• Solvents for special resins such as photosensitive resins

As shown above, they are widely used as solvents. It can also be used as a solvent for reactions such as the Grignard reaction and the Wittig reaction and as a reaction and purification solvent in the manufacture of pharmaceuticals and agricultural chemicals.

Tetrahydrofuran is also used as a synthetic raw material for nylon, polyethers, and polytetramethylene ether glycol. It is also used as an extractant in the petrochemical industry and as a heat-shrinkable film and moisture-proofing agent for vinyl chloride resin.

Properties of Tetrahydrofuran

Tetrahydrofuran is a colorless liquid with a distinctive aroma similar to ether. It is well soluble in many organic solvents and water. Tetrahydrofuran has a density of 0.8892 g/mL at 20°C, a melting point of -108.4°C, and a boiling point of 66°C.

Tetrahydrofuran can also be converted to γ-butyrolactone by oxidation. Tetrahydrofuran is also a cyclic ether containing one oxygen in a saturated five-membered ring. Tetrahydrofuran’s chemical formula is C₄H₈O and its molecular weight is 72.11.

Other Information on Tetrahydrofuran

1. Tetrahydrofuran Synthesis

Tetrahydrofuran is produced by the hydrogenation of 1,4-butindiol, which is obtained by the condensation of formaldehyde and acetylene.

Tetrahydrofuran can also be obtained by contact reduction of furan or maleic anhydride.

Tetrahydrofuran can also be obtained by oxidation of n-butane to maleic anhydride, followed by hydrogenation.

2. Formation of Peroxide by Tetrahydrofuran

When tetrahydrofuran comes in contact with air for a long time, it generates explosive peroxides. Evaporation and solidification of tetrahydrofuran that has been stored for a long time is particularly dangerous. To prevent oxidation of tetrahydrofuran, small amounts of p-cresol or hydroquinone are added to commercial products.

3. Ring-Opening Polymerization of Tetrahydrofuran

Ring-opening polymerization of tetrahydrofuran yields the polyether polytetramethylene ether glycol. Poly tetramethylene ether glycol is also called PTMG, PTMEG, polyoxy tetramethylene glycol, or poly tetrahydrofuran. Polytetrahydrofuran is also known as polytetrahydrofuran.

The molecular weight of a typical polytetramethylene ether glycol product is between 1,000 and 2,000. It is used as a raw material for polyurethanes, such as the elastic fiber Spandex and thermoplastic elastomers.

What Is Tetrafluoroethylene?

Tetrafluoroethylene (TFE), a fluorocarbon, has the molecular formula C2F2 and is known as perfluoroethylene, 1,1,2,2-tetrafluoroethene, TEF, or TFE. It is a colorless, odorless gas at room temperature, with a molecular weight of 100.02, a melting point of -131.15℃, a boiling point of -75.9℃, and a density of 1.519 g/cm3 at -76°C. Being extremely flammable and combustible, it requires careful handling.

Uses of Tetrafluoroethylene

Tetrafluoroethylene is primarily used as a raw material for fluoropolymers and fluorine-containing compounds, such as polytetrafluoroethylene (PTFE), or Teflon. Teflon is valued for its heat resistance, chemical resistance, lubricity, and non-stick properties, finding use in industrial coatings for equipment parts, machine parts, electrical parts, and household items like frying pan coatings. Other fluoropolymers include PFA and PFEP, used in various chemical, machinery, and electrical applications.

Principle of Tetrafluoroethylene

1. Production Method:

Tetrafluoroethylene is synthesized using chloroform and hydrogen fluoride, where chlorodifluoromethane is formed and then thermally decomposed to TFE. In the lab, it’s produced by thermal decomposition under reduced pressure or from pentafluoropropionic acid.

2. Chemical Properties:

As a nucleophilic, reactive organic compound, tetrafluoroethylene participates in Diels-Alder reactions and readily polymerizes to form PTFE. Hydrolysis yields toxic hydrogen fluoride, and it reacts explosively with certain metals and organometallic compounds. It also forms dibromotetrafluoroethane with bromine.

Types of Tetrafluoroethylene

While tetrafluoroethylene itself is a gas, it is commonly used in polymer forms, such as PTFE. PTFE is a resin available in various forms for different applications. As a reagent or raw material, it is usually sold as a white powder, storable at room temperature.

What Is L-Tyrosine?

L-tyrosine is an aromatic amino acid found mainly in dairy products and legumes.

L-tyrosine is a non-essential amino acid and is synthesized in the body from the essential amino acid phenylalanine by the action of enzymes in liver cells. It is a raw material for neurotransmitters (dopamine, adrenaline, noradrenaline, etc.) and melanin. In the thyroid gland, thyroxine, one of the thyroid hormones, is synthesized from L-tyrosine and iodine.

Uses of L-Tyrosine

1. Food and Medical Applications

L-tyrosine is used in food applications (food additives, supplements, etc.) and medical applications.

L-tyrosine is seldom deficient in the body since it is synthesized by the body and is available through food sources. Under these circumstances, the neurotransmitter made from L-tyrosine is deficient, necessitating the need to supplement L-tyrosine externally.

By actively taking L-tyrosine supplements or consuming L-tyrosine-rich foods, the neurotransmitter can be replenished, maintaining normal brain function. In medical use, this amino acid is used as a component of infusions administered to patients undergoing surgery.

Properties of L-Tyrosine

L-tyrosine’s molecular formula is C₉H₁₁NO₃ and its molecular weight is 181.19. It is a shiny needle-like crystal that is insoluble in water. It also contains a benzene ring, which can be detected by the “xanthoprotein reaction,” a protein coloration reaction. L-tyrosine has optical isomers (L-L-tyrosine and D-L-tyrosine) with CAS numbers 60-18-4 (L-L-tyrosine) and 556-02-5 (D-L-tyrosine).

Types of L-Tyrosine

Of the optical isomers of L-tyrosine, the L-L-tyrosine is found in most living organisms. L-L-tyrosine is also used in food additives and pharmaceuticals.

L-L-tyrosine is produced by various manufacturers and sold in milligram to kilogram volumes. The D-body of the amino acid is distributed in very few organisms, and D-L-tyrosine is an amino acid produced by the bacterium Bacillus subtilis. 

Other Information on L-Tyrosine

1. Xanthoprotein Reaction

This reaction detects amino acids containing benzene rings (L-tyrosine, phenylalanine, tryptophan, etc.). Concentrated nitric acid is added to an aqueous solution of amino acids containing benzene rings, and the solution turns yellow when boiled. The solution is then cooled, and when ammonia water is added, the color of the solution changes to orange-yellow.

2. Relationship to Disease

Phenylketonuria
L-tyrosine is a substance produced by the hydroxylation of phenylalanine by the enzyme phenylalanine hydroxylase. A congenital abnormality in phenylalanine hydroxylase results in a disease called phenylketonuria. In phenylketonuria, phenylalanine is not easily metabolized, resulting in L-tyrosine deficiency.

Leukoderma
L-tyrosine is the raw material for melanin. When melanin is produced, the benzene ring of L-tyrosine is hydroxylated by the enzyme tyrosinase to produce a substance called L-dopa. Mutations in the tyrosinase gene result in leukoderma. Leukoderma causes the skin and hair to become whitish because melanin is not produced as easily.

Cancer
L-tyrosine in proteins is phosphorylated by the enzyme L-tyrosine kinase, which converts the hydroxy group to a phosphate ester. L-tyrosine kinase is a substance that stimulates cell growth. If L-tyrosine kinase is constantly activated for some reason, cells increase abnormally and cancer develops.

3. Effect on Prevention of Gray Hair

L-tyrosine is believed to be effective in preventing gray hair because it is involved in the production of melanin. However, excessive intake may increase skin blemishes due to melanin production.

What Is Barium Titanate?

Barium titanate is a synthetic inorganic compound with a perovskite structure.

It is a white solid at room temperature with a melting point of 1,625 °C and a density of 6.02 g/㎤. It is designated as a deleterious substance and as a “barium compound”.

Uses of Barium Titanate

1. Current Main Applications

Barium titanate, also called “barium titanate ceramics,” has piezoelectric and pyroelectric properties as well as dielectric properties that cause internal polarization and store electricity when voltage is applied. Ceramic capacitors are used as materials for electronic components such as ceramic capacitors, piezoelectric elements, thermistors, and varistors. Advances in MLCC technology have enabled miniaturization of devices such as cell phones.

Piezoelectric elements are electronic components that change their internal charge under physical pressure or vibrate when voltage is applied. They are used in electronic lighters and speakers.

Thermistors are electronic components that use pyroelectricity to change internal electric charge as a result of temperature changes. They are used in temperature sensors and temperature control of heaters.

2. Future Applications

There are ongoing investigations into potential future applications of barium titanate in fields such as energy storage, actuators, sensors, and biomedical devices.

Properties of Barium Titanate

1. Physical Properties

Barium titanate is a compound with the chemical formula BaTiO₃ and has a high dielectric constant, high dielectric loss factor, and high refractive index. The Curie temperature (Tc) is around 130 °C. At T_c, a phase transition occurs from a paraelectric to a ferroelectric phase. Ferroelectricity is strongly affected by atomic defects and impurity mixtures.

2. Structure of Barium Titanate

The crystal structure of barium titanate changes from low to high temperatures in the order of rhombohedral, orthorhombic, tetragonal, and cubic. Of these, the tetragonal crystal at room temperature is a ferroelectric material, while the cubic crystal at high temperatures (120°C or higher) is an industrially important material as a paraelectric material.

It has a perovskite structure, with Ba ions at the vertices of the unit lattice, O ions at the face centers, and Ti ions at the body centers. Even in the absence of an electric field, barium titanate polarizes each ion slightly out of its normal position. This phenomenon is called spontaneous polarization. Since the direction of polarization is reversed by an external electric field, it is called ferroelectric. It is also called a “displacive ferroelectric” because ferroelectricity is induced by the mutation of ions.

Other Information on Barium Titanate

1. Production Method of Barium Titanate

1. Solid Phase Reaction Method
Barium carbonate and titanium oxide are wet-mixed, filtered, dried, granulated, molded, sintered, and pulverized. Barium carbonate is prepared from barium sulfide, barium chloride, barium hydroxide, etc. Care must be taken because the Curie point shifts to the low-temperature side when strontium is mixed in as an impurity.

Titanium dioxide is prepared by either the sulfuric acid method or the chlorine method. In the sulfuric acid method, titanium oxide is obtained by adding sulfuric acid to titanium ore FeTiO₃ to produce TiOSO₃, then adding ammonia to burn the resulting metatitanic acid (TiO(OH)₂). In the chlorine method, titanium oxide is obtained by replacing the chlorine in titanium tetrachloride with oxygen.

2. Oxalate Method
The reaction of barium chloride, titanium tetrachloride, and oxalic acid yields barium titanyl oxalate (BaTiO(C₂O₄)₂). Barium titanate is obtained by thermal decomposition. Barium titanate of high purity is synthesized industrially by this method.

3. Citric Acid Method
Barium titanate is obtained by thermal decomposition of BaTi(C₆H₆O₇)₃・6H₂O, which is prepared by reacting aqueous barium citrate and titanium citrate solutions.

4. Hydrothermal Synthesis Method
Barium titanate is obtained by heating barium hydroxide and the hydrous salt of metatitanic acid (TiO(OH)₂) under normal pressure. Barium titanate with a good crystal star can be obtained by processing under high temperature and high pressure.

5. Sol-Gel Method
Barium titanate is obtained by mixing barium hydroxide gel and titanium sol, then drying, sintering, and pulverizing. This method is suitable for the preparation of composite materials.

6. Alkoxide Method
Barium titanate is obtained by rapidly mixing titanium alkoxide and barium hydroxide in a jet mixer, then heating under annular flow and crystallizing the precipitate formed.

What Is Strontium Titanate?

Strontium titanate is a composite oxide of strontium and titanium.

It is also known as titanium trioxide (IV) strontium. Although strontium titanate is an artificial stone, it is similar to the natural mineral tauzonite in chemical composition. Strontium titanate was once considered a diamond substitute.

Despite its lower Mohs hardness of 6, compared to diamonds’ Mohs hardness of 10, it is prized for its brilliance, which is 4.3 times that of diamonds, and its fire (the dispersion of light into the spectrum of colors).

Applications of Strontium Titanate

1. Current Main Applications

Strontium titanate is widely used as a substrate for ferroelectric and superconducting thin films due to its typical perovskite structure. It plays a significant role in applied research as a substrate for Josephson devices and SQUIDs (superconducting quantum interference devices).

Additionally, it is utilized in ceramic capacitors, benefiting from its excellent dielectric and thermoelectric properties, and in varistors, sensors, and thermoelectric elements, as it can easily be converted into semiconductors with additives like niobium.

2. Future Applications

In recent years, strontium titanate has gained attention as a photocatalyst for hydrogen production. Its high stability under light irradiation and strong photoreduction power make it a promising candidate for photocatalysis using only sunlight.

Furthermore, strontium titanate is being developed as a novel substrate that combines metallic properties with high-grade perovskite-type oxide characteristics, opening up potential for unprecedented applications.

Properties of Strontium Titanate

1. Physical Properties

Strontium titanate is a white solid with the chemical formula SrTiO₃. It has a molecular weight of 183.5 and a CAS number of 12060-59-2. Its melting point is approximately 1,900°C, with a density of 5.1 g/cm³. Data on flammability or oxidizability is not available.

The crystalline system is cubic, with a lattice constant of a=0.3905 nm, typically grown by the Bernoulli method. The dielectric constant is 310 (at 27°C, 1MHz), and the coefficient of thermal expansion is 11.1×10^-6/℃ (from room temperature to 1,000°C). The phase transition temperature is 110 K, and the refractive index is 2.407 (at 589 nm).

2. Chemical Properties

It is insoluble in water and most solvents, and stable at room temperature when sealed. Strong oxidizing agents and strong acids should be avoided due to their hazardous interaction potential.

At room temperature, strontium titanate is a colorless cubic crystal with a perovskite-type structure. Below 110 K, it transforms into a tetragonal structure. When heated to high temperatures, it loses some oxygen, turns black, becomes electrically conductive, and exhibits piezoelectricity at low temperatures.

It is non-flammable and considered non-hazardous. In the event of a fire, there are no specific restrictions on fire extinguishing methods.

Other Information on Strontium Titanate

1. Safety

While considered non-hazardous and with no known effects on human health, appropriate personal protective equipment should be used to prevent exposure. In case of skin or eye contact, rinse immediately with running water and seek medical attention if discomfort persists.

Ensure work is conducted in areas with local exhaust ventilation or well-ventilated spaces, taking precautions against direct contact and inhalation of vapors and dust. Currently, no aqueous environmental toxicity, fish toxicity, bioaccumulation, or soil effects have been reported. Dispose of the product through a specialized contractor.

2. Band Gap

The band gap is a region in a crystal’s band structure where electrons cannot exist. Typical conductors, such as iron, copper, silver, gold, and aluminum, have no band gap.

Strontium titanate is an indirect transition insulator with a band gap of 3.2 eV. At room temperature, it does not show fluorescence when excited by ultraviolet light, but when excited at low temperatures, electrons, and holes form a self-bound state and emit light at 500 nm due to their coupling.

What Is Potassium Titanate?

Potassium titanate is a synthetic inorganic compound with the chemical formula K₂O·nTiO₂, where n is an integer from 1 to 12. For instance, when n equals 6, the formula becomes K₂O·6TiO₂, referred to as potassium hexatitanate.

This compound is synthesized using the flux method, employing K₂MoO₄ or K₂WO₄ as flux, or via the melting method, where a mixture of TiO₂, K₂CO₃, and K₂MoO₄ is melted at temperatures ranging from 1,200 to 1,500°C before cooling to crystallize.

Applications of Potassium Titanate

Potassium titanate varieties, such as potassium hexatitanate and potassium octatitanate, are prized for their excellent heat resistance, thermal insulation, and chemical resistance, finding widespread use in industrial applications.

Key uses include substitutes for asbestos, friction materials in brake pads and clutches, reinforcing agents for engineering plastics, filters, coatings, weather-resistant paints, fire-resistant insulation, and multilayer substrates.

Additionally, it serves in 3D printer filaments, where properties like formability, precision, strength, and rigidity are crucial.

Properties of Potassium Titanate

Potassium titanate, a white solid with the formula K₂O·4TiO₂ or K₂Ti₄O₉, has a molecular weight of 413.7 and is identified by CAS number 12056-49-4.

Details such as melting point, boiling point, and flammability are currently unspecified. This compound remains chemically stable when stored at room temperature in a sealed, dry container. While no incompatible hazardous substances are known, water contact should be avoided. As properties can vary with different n values, consulting the product’s Safety Data Sheet (SDS) is recommended upon purchase.

Other Information on Potassium Titanate

1. Safety

Potassium titanate poses risks of skin and eye irritation, with potential systemic toxicity targeting specific organs and respiratory irritation upon single exposure. Hence, handling requires utmost caution.

Though no acute or chronic aquatic toxicity or fish toxicity has been proven, the disposal should be managed by specialized contractors. It is recognized as a non-hazardous substance by fire safety regulations and is not listed as a toxic substance.

Being non-combustible, it imposes minimal restrictions during firefighting. Firefighting measures should align with those for other hazardous materials.

2. Handling Methods

Ensure local exhaust ventilation or adequate ventilation in the workspace to prevent inhalation of vapors and dust. Protective gear, including respirators, safety glasses, masks, gloves, and depending on the task, protective clothing, boots, headgear, and arm covers, are recommended for workers.

3. Potassium Titanate Fiber

Potassium titanate fiber, known for its high strength, rigidity, and aspect ratio, is utilized in various applications such as reinforcement materials for plastics, friction modifiers for automobile brakes, and precision filters.

It is especially valued for its heat insulation, resistance, and chemical resilience, enhancing thermoplastics, plastic foams, and cement reinforcements, as well as insulators and heat-resistant materials.

Furthermore, crystalline titanate fiber, a derivative, exhibits ion adsorption properties and promising applications in wastewater treatment, radioactive waste management, and as a catalyst or filter medium.

4. Structure of Potassium Titanate Fiber

Structural analysis of potassium titanate fibers synthesized with n values of 1, 2, 4, 6, and 8 reveals distinct layered and tunnel structures for n=2 and 4, and n=6 and 8, respectively.

While both structures are synthesized as fibers, their chemical and physical properties significantly differ. Layered structure fibers are chemically active and allow for the synthesis of various derivatives due to the strong exchangeability of potassium ions. In contrast, tunnel-structured fibers showcase superior thermal insulation, heat resistance, and physicochemical properties.

What Is Sodium Thiosulfate?

Sodium thiosulfate, known for its applications in medical care, photo processing, and water treatment, is a versatile inorganic compound characterized by its strong reducing power and solubility in water.

Uses of Sodium Thiosulfate

From treating cyanide poisoning and relieving chemotherapy side effects to its role in photographic fixing and dechlorination in water treatment, sodium thiosulfate’s utility spans a broad range of industries.

Properties of Sodium Thiosulfate

Available in anhydrous and pentahydrate forms, sodium thiosulfate exhibits distinct physical properties, including its phase at room temperature and solubility, contributing to its wide-ranging applications.

Other Information on Sodium Thiosulfate

1. Manufacturing Process

Produced industrially from sodium sulfide or sulfur dye waste products, or synthesized in the laboratory, sodium thiosulfate’s production methods underscore its chemical versatility.

2. Reaction of Sodium Thiosulfate

Its decomposition under heat or reaction with acids, alongside its role in iodometry, highlights sodium thiosulfate’s reactivity and utility in analytical chemistry.

3. Regulatory Information

Not subject to major regulations, sodium thiosulfate requires standard precautions for safe handling and storage.

4. Handling and Storage Precautions

Handling and storage precautions are as follows

• Keep the container tightly closed and store it in a cool, dark place out of direct sunlight.
• Use only outdoors or in well-ventilated areas.
• Wear protective gloves and glasses when using.
• Wash hands thoroughly after handling.
• In case of skin contact, wash with soap and water.
• In case of eye contact, rinse cautiously with water for several minutes.

What Is Thiourea?

Figure 1. Basic Information on Thiourea

Thiourea, an organosulfur compound replacing urea’s oxygen with sulfur, is utilized in various industries for its unique chemical properties and applications, from pharmaceuticals to dyes and rubber additives.

Uses of Thiourea

Key uses span urethane resins a polymer with urethane bonds, also called polyurethane or urethane rubber production, as well as pharmaceuticals, dyes, and as a source of hydrogen sulfide in qualitative analysis, showcasing its broad utility.

Properties of Thiourea

Soluble in water and ethanol, thiourea is known for its planar structure, facilitating its role in redox reactions and complex formation with metals.

Structure of Thiourea

Figure 2. Structure of Thiourea

The molecule’s structure, featuring both thiol and amine functionalities, underpins its reactivity and applications in catalysis and organic synthesis.

Other Information on Thiourea

1. Reduction Reaction Using Thiourea

Figure 3. Reaction Using Thiourea

Thiourea’s capability to reduce peroxides to diols and serve as a reducing agent in ozone decomposition is highlighted, alongside its odorless and less volatile nature compared to other sulfur sources.

2. Thiourea as a Sulfur Source

Its function as a sulfur atom source in synthetic chemistry, particularly in the synthesis of metal sulfides and organic thiols, underlines its versatility and importance in material science and organic synthesis.

What Is Thioglycolic Acid?

Thioglycolic acid (TGA), known for its pungent odor and versatility in chemical reactions, is used across a range of industries, from cosmetics to polymer manufacturing, due to its unique functional groups.

Uses of Thioglycolic Acid

From altering hair structure in beauty treatments to synthesizing complex synthetic resins, thioglycolic acid’s reductive properties and ability to complex with metals make it a valuable chemical in various applications.

Properties of Thioglycolic Acid

Its solubility in water and organic solvents, combined with its reactivity towards oxidation and reduction, underlines its importance in chemical synthesis and industrial processes.

Structure of Thioglycolic Acid

The dual presence of thiol and carboxylic acid groups in thioglycolic acid facilitates its involvement in a wide array of chemical reactions, serving as both a complexing and reducing agent.

Other Information on Thioglycolic Acid

Production Methods

Thioglycolic acid is produced via several methods, including reactions with chloroacetic acid, glycolic acid, and glycolate esters with hydrogen sulfide, showcasing its chemical versatility and industrial significance.

What Is Dimer Acid?

Dimer acid, also known as dimeric acid, is a dicarboxylic acid featuring a 36-carbon (C36) alkyl group. It is produced by dimerizing C18 unsaturated fatty acids from vegetable oils and fats, such as linoleic acid and oleic acid. Vegetable oils and fats from waste cooking oil recycling are also used as raw materials.

The structure of dimer acid products varies based on the fatty acids used and the polymerization method. The industrial quality of dimer acid varies, containing different amounts of trimer and other substances in addition to the dimer.

Uses of Dimer Acid

Dimer acid is utilized as a modifier for thermosetting and thermoplastic resins, as a raw material for polyamidoamine, an epoxy resin curing agent, and thermoplastic polyamide resin. It is used in paints, inks, and adhesives.

Its flexibility makes it suitable for use as a lubricant and cutting oil. Dimer acid is also added to corrosion inhibitors and rust inhibitors, and in cosmetics as a blocking agent to prevent skin moisture evaporation, maintaining skin moisture.