月: 2023年1月

What Is Sodium Perborate?

Sodium perborate, an inorganic compound with the formula NaBO₃, primarily exists as monohydrate or tetrahydrate. Despite being represented as the sodium salt of HBO₃, perborate does not exist as a free acid but is structurally comprised of a boron atom bonded to a hydroxide ion.

Uses of Sodium Perborate

As a versatile compound, sodium perborate serves various roles, including as a bleaching agent in textiles, a component in detergents, mouthwashes, and teeth whitening products, as well as in laboratory reagents and other applications.

Properties of Sodium Perborate

1. Sodium Perborate Monohydrate

Characterized by its white crystalline or powder form, sodium perborate monohydrate decomposes above 60°C and is slightly soluble in water, with specific applications benefiting from its chemical properties.

2. Sodium Perborate Tetrahydrate

The tetrahydrate form, a colorless, odorless solid, is noted for its oxidizing effects in aqueous solutions, liberating hydrogen peroxide, and is widely used as a bleaching agent.

Types and Availability

Commercially, sodium perborate is mostly sold as tetrahydrate, with the monohydrate form being less common. Available in various capacities, these reagents cater to laboratory use and are stable at room temperature.

Other Information on Sodium Perborate

1. Synthesis

The compound is synthesized through a two-step reaction involving sodium borate, sodium hydroxide, and hydrogen peroxide, leading to the production of sodium perborate tetrahydrate, with the monohydrate form obtainable through heating.

2. Hazardous Properties

Both forms of sodium perborate pose potential hazards, including fire risks, toxicity if swallowed or inhaled, and serious eye damage. They are also suspected of causing reproductive toxicity and are harmful to aquatic life.

3. Regulatory Information

Due to its hazardous nature, sodium perborate is subject to strict regulations, including classifications under the Fire Service Act and PRTR Law, necessitating careful handling in compliance with legal standards.

What Is Copper Bromide?

Copper bromide is an inorganic compound available as crystals, powder, or lumps, with a color ranging from light yellowish-green to light grayish-green. It is regulated under various environmental and safety laws due to its classification as a hazardous substance.

Uses of Copper Bromide

Primarily used as a synthetic raw material and catalyst, copper bromide has garnered interest in solar cell technology within photovoltaic power generation, showcasing potential in improving solar cell efficiency through its unique properties when synthesized with other copper compounds.

Properties of Copper Bromide

There are two forms of copper bromide: copper (I) bromide (CuBr) and copper (II) bromide (CuBr₂). Copper (I) bromide, an antimagnetic solid with a melting point of 504°C, is soluble in acids and bases, and slightly soluble in water. It often appears colored due to impurities but is colorless when pure. Copper (II) bromide, a dark green solid, is used as a brominating agent and is soluble in water and various organic solvents.

Structure of Copper Bromide

Copper (I) bromide has a polymer structure similar to zinc sulfide, interconnected by bromide ions in a tetrahedral coordination. This structure makes it insoluble in most solvents, though it forms addition compounds with Lewis bases, resulting in complexes with varied applications in organic synthesis.

Other Information on Copper Bromide

1. Synthesis of Copper (I) Bromide

Typically synthesized by the reduction of copper (II) salts with sulfite in the presence of bromide, copper (I) bromide can also be produced from copper powder and hydrobromic acid.

2. Application of Copper (I) Bromide

It is extensively used in organic synthesis, including the Sandmeyer reaction for converting aniline compounds to aryl bromides, and as a catalyst in atom transfer radical polymerization and copper-catalyzed cross dehydrogenative coupling.

3. Properties and Safety of Copper (II) Bromide

Copper (II) bromide is primarily utilized as a brominating agent in photography and organic synthesis. It is toxic if ingested and can irritate the skin, eyes, and respiratory system, highlighting the need for careful handling.

What Is Methyl Bromide?

Methyl bromide (CH₃Br), also known as bromomethane, is a type of alkyl halide recognized under various classifications for its hazardous properties by the Industrial Safety and Health Law. It is also categorized as a disease-causing chemical substance under the Labor Standards Law and a Class 1 Designated Chemical Substance under the PRTR Law, requiring careful handling.

Uses of Methyl Bromide

Previously a widespread fumigant for soil disease and weed control, and quarantine treatments, methyl bromide was identified as an ozone-depleting substance in 1992. Its use was phased out in developed countries by 2005 and in developing countries by 2015, except for quarantine and pre-shipment processes which are not regulated.

Properties of Methyl Bromide

1. Physical Properties

A colorless, odorless gas, methyl bromide has a melting point of -93.66°C and a boiling point of 4°C. It is highly flammable, with a spontaneous combustion temperature of 537°C and an explosive range of 10 to 16 vol%. It is heavier than air, with specific gravity indicating its density as a liquid.

2. Chemical Properties

Methyl bromide is soluble in water and miscible with several organic solvents. It decomposes upon heating, emitting toxic fumes of hydrogen bromide and bromine, and reacts with metals in the presence of water, potentially causing fire and explosion hazards.

Other Information on Methyl Bromide

1. Production Method

Typically produced by the reaction of methanol with hydrobromic acid, methyl bromide can also be generated in processes alongside tetrabromobisphenyl A.

2. Safety

Exposure to methyl bromide can harm the nervous, respiratory, liver, kidney, and digestive systems, and pose risks of genetic disorders and adverse reproductive effects. It is also toxic to aquatic life, requiring careful disposal and handling with appropriate protective gear.

3. Handling

When handling methyl bromide, use respiratory protection, gloves, eye protection, and protective clothing, and ensure the presence of safety showers and eye wash stations. In case of fire, evacuating the area is advised due to the high risk of explosion.

4. First Aid Treatment

In case of exposure, ensure the affected individual is moved to fresh air and rinsed thoroughly if skin or eye contact occurs. Due to its lack of odor at dangerous concentrations, ensure adequate ventilation when using methyl bromide.

5. Storage

Store in a cool, dry, well-ventilated area away from heat, sparks, open flames, and strong oxidizers, ensuring containers are sealed and secured.

What Is Potassium Bromide?

Potassium bromide, a white crystalline compound, is formed by the combination of potassium and bromine, with a melting point of 734°C and a boiling point of 1,435°C. It is industrially produced by reducing potassium bromate through the reaction of potassium hydroxide and bromine, or by reacting hydrogen bromide with potassium hydroxide.

Crystallization of a saturated aqueous solution of potassium bromide by adding ethanol or another solution results in luminescence due to crystal luminescence.

Uses of Potassium Bromide

Transparent to infrared light, single crystals of potassium bromide are utilized as prisms for infrared spectroscopy. Its effect of suppressing central excitation in the cerebral cortex makes it a valuable raw material for nerve sedatives and antiepileptic drugs in the medical field. Additionally, potassium bromide finds applications in photography as a raw material for silver bromide, in developing solutions, as a chemical reagent, and in soap production.

Properties of Potassium Bromide

While soluble in alcohol and water, potassium bromide is insoluble in ether. It is hygroscopic, deliquescent, and should be stored in dry containers. Its aqueous solution ionizes into potassium and bromide ions, maintaining a neutral pH of 7. Reactions with sulfuric acid liberate bromine, and it forms complex salts when reacted with metal halides, such as copper (II) bromide.

Structure of Potassium Bromide

With the chemical formula KBr, potassium bromide has a molar mass of 119.002 g/mol and a density of 2.75 g/cm³. Its crystal structure mirrors that of sodium chloride, featuring an octahedral coordination structure.

Other Information on Potassium Bromide

1. Synthesis of Potassium Bromide

The traditional synthesis involves the reaction of iron bromide (Fe₃Br₈) with potassium carbonate, where iron bromide is produced by reacting excess bromine (Br₂) with iron scraps in water.

2. Optical Applications of Potassium Bromide

Transparent in the near-ultraviolet to far-infrared regions (0.25-25 μm), potassium bromide is used in prisms or optical windows due to its refractive index of approximately 1.55 at 1.0 μm. It is ideal for infrared spectroscopy as it does not interfere with the measurement area and is used in solid-state NMR to adjust the magic angle during ¹³C measurement.

3. Applications in Medicine and Veterinary Medicine

As a pioneering therapeutic agent for epilepsy, potassium bromide is currently used in combination with other drugs for treating Dravet syndrome and as an antiepileptic drug for dogs, often as a first-line drug or in conjunction with phenobarbital when it alone is ineffective.

4. Application to Silver Halide Photography

Previously a staple in the developing process of silver halide photography and as a development inhibitor, potassium bromide’s use has declined but remains in specialized applications such as astrophotography. Sodium thiosulfate has largely replaced it as a fixing agent.

What Is Ultramarine Blue Pigments?

Ultramarine, also known as ultramarine blue pigments, is an inorganic pigment derived from the mineral lapis lazuli. It is composed of complex sodium aluminosilicates with sulfide and sulfate ions, known for its vivid deep blue color.

This pigment gained fame as “Vermeer blue” due to its use by the painter Johannes Vermeer in many of his renowned works.

Uses of Ultramarine Blue Pigments

Ultramarine blue pigments are primarily used for their intense blue color in various applications, including water-based paints, printing inks, and other paints. It is also employed in the coloring of paper, rubber, plastics, and textiles like wallpaper and chintz, as well as in murals and tableaux.

Synthetically produced ultramarine blue is made from a mixture of materials such as ochre, sodium carbonate, sulfur, and charcoal. These synthetic variants are cost-effective and widely used in mass-produced products across different industries.

Due to its non-toxic nature, ultramarine blue is also utilized in cosmetics.

What Is Boron Nitride?

Boron nitride, an inorganic compound made of boron and nitrogen is a colorless and flame-retardant crystal. It has the chemical formula BN, a molecular weight of 24.82, and a CAS No. of 10043-11-5. Its isoelectronic structure with carbon grants it many properties similar to those of carbon.

Structure of Boron Nitride

Boron nitride exists in three main allotropes: hexagonal h-BN (α-BN), cubic c-BN (β-BN), and wurtzite w-BN (γ-BN).

1. Hexagonal (h-BN)

Hexagonal boron nitride, also known as h-BN, α-BN, or graphitic boron nitride, is the most stable form. It features a layered structure akin to graphite, with strong covalent bonds within layers and weak van der Waals forces between them.

2. Cubic (c-BN)

Cubic boron nitride, resembling diamond in structure, is less stable than hexagonal BN. It shares the sphalerite crystal structure with diamond, hence also referred to as β-BN or c-BN.

3. Wurtzite (w-BN)

The wurtzite form, w-BN, mirrors the structure of lonsdaleite, a rare hexagonal carbon polymorph. Its hardness surpasses that of commercial borides but is softer than c-BN.

Properties of Boron Nitride

1. Physical Properties

With high heat resistance, boron nitride can withstand temperatures up to 1,500°C in a vacuum and 2,200°C in an inert atmosphere. Its low thermal expansion coefficient and good thermal conductivity make it an ideal high-thermal-conductivity ceramic.

2. Other Characteristics

Boron nitride also boasts stability against chemicals, excellent corrosion resistance, and insulating properties suitable for high-frequency applications.

Uses of Boron Nitride

Due to its thermal conductivity and electrical insulation, boron nitride is ideal for heat-dissipating resin sheets and substrates, as well as additives in various materials for enhanced heat resistance and lubrication.

Other Information on Boron Nitride

1. Production Process

Boron nitride is produced by heating borax with ammonia or boric acid with ammonium chloride, resulting in a crystalline, scale-like, and slippery material.

2. Legal Information

Not designated under the Poisonous and Deleterious Substances Control Law or the Fire Service Law, boron nitride is listed as a Class 1 Designated Chemical Substance under the PRTR Law.

3. Handling and Storage Precautions

Store in a sealed container in a dry cool place. Use protective gear

when handling and avoid strong oxidizers. In case of contact, wash the affected area with soap and water or rinse eyes with water.

What Is Titanium Nitride?

Titanium nitride, a bronze-colored crystalline solid, is produced by heating titanium oxide and carbon in nitrogen or through surface modification via nitrogen plasma treatment on a titanium substrate. Its thin films are known for their gold-like spectral qualities, including infrared reflectivity, which gives them a distinctive yellowish appearance.

Uses of Titanium Nitride

With superior adhesion, wear resistance, corrosion resistance, and heat resistance, titanium nitride serves as an excellent coating material for various tools and equipment, including cemented carbide and cutting tools, as well as food containers and processing equipment. Its attractive golden hue also makes it popular for decorative applications and in the medical field for implants and surgical tools, benefiting from its non-toxic nature.

Properties of Titanium Nitride

Titanium nitride exhibits hardness that is comparable to diamond, showcasing a Vickers hardness of 2,400 and an elastic modulus of 251 GPa. It has a melting point of 2,930°C, a coefficient of thermal expansion of 9.35×10⁻⁶K⁻¹, and transitions to a superconductor at 5.6K. Its ability to reflect infrared radiation, resembling gold’s reflective spectrum, contributes to its yellowish tint. The material transitions from a cooper pair insulator to a superinsulator at temperatures near absolute zero, indicating a phase where electrical resistance becomes infinite.

Structure of Titanium Nitride

Titanium nitride (TiN) has a molar mass of 61.874 g/mol and features a sodium chloride-type crystal structure with a 1:1 stoichiometric ratio. Its octahedral coordination structure supports thermodynamically stable TiNx compounds within a range of x=0.6 to 1.2.

Other Information on Titanium Nitride

1. Titanium Nitride in Meteorites

Occurring naturally only in meteorites, titanium nitride is identified as osbornite.

2. Fabrication of Titanium Nitride

Titanium nitride films are primarily produced via physical or chemical vapor deposition. These methods involve sublimating high-purity titanium that reacts with nitrogen in a high-energy vacuum environment or through reactive growth in a nitrogen atmosphere, such as annealing, to form coatings on titanium workpieces.

3. Reaction of Titanium Nitride

While stable at room temperature, titanium nitride begins to oxidize in air at 800℃ and may corrode slowly in concentrated acids at high temperatures. It is slightly soluble in aqua regia, nitric acid, and hydrofluoric acid, but insoluble in water.

What Is Silicon Nitride?

Silicon nitride (Si₃N₄) is an odorless white to gray powder with a molecular weight of 140.28 and is known for its robustness and thermal stability. It was first reported by Henri Etienne Sainte-Claire Deville and Friedrich Wöhler in 1857.

Uses of Silicon Nitride

Employed as a high-temperature structural material, silicon nitride is ideal for components in harsh environments such as engines, gas turbines, and various welding and combustion parts. Its high wear resistance and mechanical strength also make it suitable for use in semiconductor manufacturing equipment, die and mold parts, and wear-resistant applications.

Properties of Silicon Nitride

1. Physical Properties

Notable for its strength at high temperatures, silicon nitride remains stable up to about 1,900°C in inert atmospheres, featuring high toughness, a low coefficient of thermal expansion, and excellent thermal shock resistance.

2. Other Characteristics

While resistant to most acids, silicon nitride is vulnerable to hydrofluoric, hydrochloric, and nitric acids. It undergoes a phase transition from α-type to β-type between 1,400°C and 1,500°C, affecting its structural properties.

Structure of Silicon Nitride

Silicon nitride exists in three polymorphs: α-phase, β-phase, and γ-phase. The α and β phases, which are the focus of material development, have distinct crystal structures and properties, while the γ-phase, synthesized under extreme conditions, resembles cubic boron nitride in structure.

Other Information on Silicon Nitride

1. Production Process

Industrially, silicon nitride is produced through direct nitridation of silicon powder, reduction of silicon dioxide with carbon in nitrogen or ammonia, or vapor phase synthesis from silicon halide or monosilane with ammonia.

2. Legal Information

Not classified under major hazardous substances laws but is noted in the Industrial Safety and Health Law as a substance requiring notification.

3. Handling and Storage Precautions

• Store in a dry, cool, and dark place, ensuring containers are tightly closed.
• Operate in well-ventilated areas or outdoors to avoid contact with water, which can generate alkaline substances.
• Protective gloves and glasses are recommended during use, with thorough washing post-handling.

What Is Aluminum Nitride?

Aluminum nitride (AlN) is an inorganic compound with colorless or gray crystals. It stands out for its high thermal conductivity and low electronic conductivity, making it exceptionally stable against oxidation among nitrides.

Uses of Aluminum Nitride

Aluminum nitride is primarily used in heat-sensitive semiconductor and electronic components due to its excellent thermal conductivity, electrical insulation, and similar thermal expansion properties to various semiconductors. It finds applications in substrates for power transistor modules, LED mounting, and IC packages, as well as plasma etch components, wafer chucks, and heater equalization plates. Additionally, its fine powder form improves resin performance by enhancing filler compatibility, flowability, and heat dissipation when mixed with resins like epoxy, silicone, and BT resin.

Properties of Aluminum Nitride

AlN is a colorless or gray crystalline solid with a molecular weight of 40.99 and a specific gravity of 3.3. It decomposes at 2,150°C without melting under ambient pressure. The sintered form is chemically stable and insoluble in common acids and bases. However, powdered AlN reacts with water vapor to form aluminum hydroxide and ammonia, particularly in high-pH solutions. Therefore, powdered AlN requires storage in high-purity nitrogen or dry air to prevent hydrolysis, unlike its sintered form, which exhibits high chemical resistance and does not decompose upon hydrolysis.

Sintered aluminum nitride, formed by mixing AlN powder with binders and sintering at temperatures above 1,700°C, offers high thermal conductivity (70 to 200 W/m-K) and thermal emissivity, significantly surpassing alumina (Al₂O₃) and matching the thermal expansion coefficient of silicon, enhancing its resistance to thermal deformation and shock.

Other Information on Aluminum Nitride

Aluminum Nitride Production Methods

Aluminum nitride can be synthesized through several methods:

1. From Aluminum Oxide: A high-pressure reaction between bauxite, coke, and nitrogen at 1,700°C yields AlN.

　　Al₂O₃ + 3C + N₂ → 2AlN + 3CO

2. Direct Reaction of Aluminum Powder With Nitrogen: Aluminum powder reacts with nitrogen at 600°C, with the process optimized between 800 to 1,000°C to prevent agglomeration.

　　2Al + N₂ → 2AlN

3. Reaction of Aluminum Chloride With Ammonia: This method, suitable for forming thin films, involves reacting aluminum chloride with ammonia at 1,200 to 1,500°C.

　　AlCl₃ + NH₃ → AlN + 3HCl

What Is Ammonium Sulfate?

Ammonium sulfate, an ammonium salt of sulfuric acid, has the chemical formula (NH₄)₂SO₄. It is a white, odorless, crystalline solid with a slightly acidic pH of 4.5 to 5.0. Upon heating, it decomposes at 120°C and melts at 357°C, releasing ammonia. Industrially, it is produced by reacting sulfuric acid with ammonia. 

Uses of Ammonium Sulfate

Primarily used as a nitrogen fertilizer in agriculture, ammonium sulfate is essential for plant growth. Its quick absorption by plant roots and low cost make it a popular choice. It is also used to harden snow at ski resorts and precipitate proteins in biochemical applications.

Properties of Ammonium Sulfate

With a molecular weight of 132.14, ammonium sulfate is soluble in water and virtually insoluble in ethanol. It decomposes upon heating, forming various compounds and eventually decomposing into ammonia, sulfur dioxide, and nitrogen.

Structure of Ammonium Sulfate

This ionic compound consists of two ammonium ions (NH₄⁺) and one sulfate ion (SO₄^2-), showcasing a typical ionic bond structure. The ammonium ion features one nitrogen atom surrounded by four hydrogen atoms, and the sulfate ion comprises a sulfur atom bonded to four oxygen atoms.

Other Information on Ammonium Sulfate

Ammonium Sulfate Production Methods

1. Synthetic Method: A neutralization reaction between sulfuric acid and ammonia. This method is preferred for producing pharmaceuticals and reagents due to its operational advantages.

2. Byproduct of Coke Production: Produced by reacting discharged ammonia during coke production with concentrated sulfuric acid.

3. Caprolactam Synthesis Byproduct: Generated as a byproduct in the production of caprolactam, a nylon precursor, through several chemical reactions, including the oxidation of cyclohexane and Beckmann rearrangement.

4. Acrylamide Synthesis Byproduct: Formerly produced as a byproduct of acrylonitrile hydrolysis using sulfuric acid as a catalyst, though less common now due to enzymatic processes.

5. Coal Boiler Emissions Treatment: Formed by reacting sulfur dioxide gas from coal combustion with ammonia.