月: 2023年1月

What Is Butadiene?

Butadiene, specifically 1,3-butadiene, is an industrially significant unsaturated hydrocarbon with two carbon-carbon double bonds. It is produced from naphtha and primarily used as a raw material in manufacturing synthetic rubbers like styrene butadiene rubber (SBR) and butadiene rubber (BR), commonly used in tires. Butadiene is a highly flammable gas, necessitating careful handling to avoid ignition and ensure proper ventilation. Additionally, it requires antioxidants and polymerization inhibitors during storage due to its propensity for polymerization reactions.

Butadiene Manufacturing Process and Uses

Butadiene is derived from petroleum through two main methods: extraction from the C4 fraction, a byproduct of naphtha cracking, and dehydrogenation of butane and butene. Its primary application is in synthetic rubber production for items like automobile tires, ABS resin, and nylon 66.

Structural Isomers of Rubber Made From Butadiene

Rubber produced from 1,3-butadiene undergoes polymerization, leading to various structural isomers based on the manufacturing conditions. This results in different types of butadiene rubbers with varied properties. High cis-type butadiene rubber, known for its low glass transition temperature and excellent low-temperature properties, is used in automotive tires, O-rings, and gaskets. Low cis-type butadiene rubber is also utilized in tires and as a resin modifier.

Butadiene Safety and Regulations

Butadiene, typically a gas at room temperature, is sold as a liquefied gas in cylinders. Its extreme flammability and combustion risk require strict safety measures, including proper ventilation and the absence of ignition sources. Due to its tendency to undergo polymerization reactions, adding inhibitors and antioxidants is crucial during storage. Butadiene is also regulated under OSHA guidelines and recognized as a mutagenic substance.

What Is Furfural?

Furfural, an aromatic aldehyde with the formula C₅H₄O₂, is produced in large quantities from agricultural by-products like corn cobs and sugarcane bagasse. Recognized for its role as a renewable, non-petroleum-based chemical feedstock, furfural is obtained through steam treatment of biomass followed by distillation.

Uses of Furfural

As a versatile material, furfural is employed in the manufacture of resins and solvents, and as a precursor for various industrial chemicals. Its applications include surface treatments for chemical and heat resistance, lubricant refining, decolorizing agents, and as a component in pesticides.

Properties of Furfural

Furfural is a colorless liquid that becomes yellow upon air exposure, with an almond-like aroma. It is soluble in most organic solvents and slightly soluble in water and alkanes. Notably reactive, furfural can decompose at high temperatures or react vigorously with strong acids and bases, posing fire and explosion risks.

Structure of Furfural

The structure of furfural includes a formyl group attached to the 2-position of a furan ring, making it a key molecule in organic chemistry with a density of 1.16 g/mL and a molar mass of 96.09 g/mol.

Other Information on Furfural

1. Synthesis of Furfural

Furfural is synthesized from biomass containing polysaccharides or hemicelluloses, which, when hydrolyzed and dehydrated under acidic conditions, yield furfural. Corn or oat hulls are particularly efficient sources, providing substantial yields.

2. Furfural as a Raw Material

Beyond its use as a solvent, furfural serves as a precursor for producing furan resins, tetrahydrofuran, and hydroxymethylfurfural, showcasing its versatility in chemical synthesis and its presence in various heated foods.

3. Hazards of Furfural

Exposure to furfural may irritate the respiratory system and skin, potentially leading to severe health effects if inhaled or ingested. Proper handling and safety measures are essential to mitigate risks associated with its use.

What Is Furfuryl Alcohol?

Furfuryl alcohol, with the molecular formula C₅H₆O₂, is a heterocyclic aromatic compound known as 2-furanmethanol. It is characterized by a burnt smell and is a clear, colorless to yellowish-brown liquid that darkens upon exposure to light or air. Its notable physical properties include a melting point of -20.2°C, a boiling point of 170°C, and a density of 1.13 g/mL. Furfuryl alcohol is readily soluble in ether, alcohols, benzene, and chloroform, and is miscible in water.

Uses of Furfuryl Alcohol

Its primary uses include raw material for synthetic resins, solvent applications, and as a chemical raw material in the production of oxygen-containing five-membered rings. It finds applications in semiconductor devices, surfactants, and increasingly in water-based inks as an alternative to VCO-emitting oil-based inks. As a synthetic resin, it contributes to the manufacturing of furan resins used in casting and as a component in self-igniting rocket fuel.

Properties of Furfuryl Alcohol

Industrially synthesized from furfural found in agricultural by-products, furfuryl alcohol participates in Diels-Alder reactions, hydroxymethylation, and forms ethers through reactions with halides. It can undergo dehydration polymerization to produce furan resins. A notable reaction involving furfuryl alcohol is the Ahmatovich reaction for synthesizing dihydropyran rings.

Furfuryl Alcohol Types

Marketed primarily for research and development, furfuryl alcohol is available in various quantities, from small-scale reagent bottles to larger containers. It is also recognized as a safe flavoring agent and food additive.

Other Information About Furfuryl Alcohol

Furfuryl alcohol, with a low flash point of 65°C, falls under specific classifications for hazardous materials, requiring adherence to safety regulations under multiple laws. However, its use as a food additive and flavoring agent is sanctioned within regulated limits.

What Is Fumaric Acid?

Fumaric acid is the simplest unsaturated dicarboxylic acid and is widely found in nature. It is a colorless crystalline powder with no odor but a strong sour taste. Industrially, fumaric acid is mainly produced by isomerizing maleic acid, a geometric isomer of fumaric acid.

Physicochemical Properties of Fumaric Acid

1. Name
English name: fumaric acid
IUPAC name: (2E)-but-2-enedioic acid

2. Molecular Formula
C4H4O4

3. Molecular Weight
116.07 4. melting point

4. Melting Point
300-302℃ (in sealed tube)

5. Solvent Solubility
Soluble in ethanol, insoluble in water, insoluble in benzene

Characteristics and Uses of Fumaric Acid

1. Use as a Fungicide

This compound is used as a disinfectant for fresh food due to its bactericidal properties. Its mechanism of action is as follows.

Fumaric acid’s mechanism of action as a fungicide:

1. The carboxyl group is taken into the bacteria in a non-resolved state.
2. The dissociation of the carboxyl group in the cytoplasm lowers the pH of the cytoplasm.
3. As a result of (2) above, enzyme activity in the cytoplasm decreases, inducing metabolic abnormalities and killing the bacteria.

2. Examples of Use in the Food Industry, Livestock Industry, and Medical Field

Fumaric acid is recognized as safe as a food additive, and is used as an acidulant, expander, pH adjuster, and seasoning. In the livestock and agricultural fields, fumaric acid is used as an additive in feed and as a fungicide and algaecide for plants. In the industrial field, it is used as a raw material for synthetic resins and dyes. In the medical field, fumaric acid esters made from fumaric acid are being studied for their effectiveness in treating psoriasis.

3. Role in the body

Fumaric acid plays an important role in the energy production process of organisms that breathe oxygen. Specifically, it exists as an intermediate in the citric acid circuit, where it is produced from succinic acid and converted to malic acid.

Differences in Chemical Properties Between Fumaric Acid and Maleic Acid

Fumaric acid has geometric isomers. The trans form is fumaric acid and the cis form is maleic acid.

Interestingly, the chemical properties of these compounds are very different. Specifically, fumaric acid, the trans form, is less prone to intramolecular dehydrocondensation than maleic acid, and its solubility in water is much lower than that of maleic acid. These differences in properties can be explained by the steric positioning of the two carboxyl groups in these isomers. Please refer to the following article for a detailed explanation of this principle.

What Is Silver Fluoride?

Silver fluoride, an inorganic compound of silver and fluorine, exists in multiple forms depending on the oxidation state of silver, including silver(I) fluoride (AgF), silver(II) fluoride (AgF₂), and silver(III) fluoride (AgF₃). It is recognized under the GHS classification as skin corrosive and irritant.

Uses of Silver Fluoride

Silver fluoride’s applications span dental antiseptics, dentistry materials, electronic circuit boards, metallic nanowires for integrated circuits, and cosmetics. Silver(II) fluoride, with its potent oxidizing properties, serves as a fluorinating and oxidizing agent in organic synthesis.

Properties of Silver Fluoride

Silver(I) fluoride is notable for its exceptional solubility in water, contrasting with other silver halides which are insoluble. This property is attributed to the high electronegativity of fluorine. Additionally, while it is photosensitive, its application in photographic emulsions is limited due to its low sensitivity and high solubility.

Types of Silver Fluoride

The composition and properties of silver fluoride vary with the silver ion’s oxidation number, resulting in distinct forms such as silver(I) fluoride, a water-soluble compound with sodium chloride-type crystal structure; silver(II) fluoride, a powerful fluorinating agent with an octahedral crystal structure; and silver(III) fluoride, a less common form characterized by its bright red color and antimagnetic properties.

Structure of Silver Fluoride

Silver(I) fluoride crystals adopt a cubic crystal system, akin to the structure of sodium chloride, with equal axes intersecting at 90 degrees, forming an equiaxed system.

Other Information on Silver Fluoride

Production methods for silver fluoride vary: Silver(I) fluoride can be synthesized from silver oxide and hydrofluoric acid, whereas silver(II) fluoride is produced by reacting silver(I) fluoride with fluorine gas. Silver fluoride is regulated as a deleterious substance under various safety and environmental laws due to its hazardous nature.

What Is Lithium Fluoride?

Lithium fluoride, a white or nearly white odorless powder, is an inorganic compound formed from lithium and fluorine. It exhibits low solubility in water, standing out for its unparalleled ultraviolet light transmittance, making it an exceptional optical material. Notably, it boasts a high melting point of 1,063°C and considerable hardness, ensuring stability under high-temperature conditions.

This compound serves as a precursor for lithium hexafluorophosphate in lithium batteries, a coolant in nuclear reactors, a UV optical material, and more.

Uses of Lithium Fluoride

Lithium fluoride finds applications in lithium batteries, nuclear reactor coolants, optical materials, and conductive materials.

1. Raw Materials for Lithium Batteries

As a key precursor to lithium hexafluorophosphate, an electrolyte for lithium batteries, lithium fluoride is synthesized through a reaction with hydrogen fluoride and phosphorus pentachloride.

2. Reactor Coolant

Due to its chemical stability, lithium fluoride, especially when highly concentrated and mixed with beryllium fluoride (FLiBe), is an efficient nuclear reactor coolant. This mixture, notable for its low melting point and high thermal conductivity, excels in heat dispersion within reactors.

3. Optical Materials

With the highest ultraviolet light transmittance among crystals, lithium fluoride is utilized in special optical components for the UV spectrum. It also plays a role in X-ray spectrometry diffraction crystals and radiation exposure recording instruments.

4. Conductive Material

Boasting a high dielectric constant, lithium fluoride enhances electron injection in cathodes for OLEDs and synthesized LEDs, typically applied as a thin layer of about 1 nm.

Properties of Lithium Fluoride

Lithium fluoride (LiF), with a molecular weight of 25.94, forms clear, colorless crystals. It’s virtually insoluble in water yet dissolves in ethanol and dimethylformamide. Its robust melting and boiling points are 1,063°C and 1,686°C, respectively. Characterized as an ionic crystal, it has a cubic structure with a lattice constant of 3.01 Å, contributing to its hardness and industrial importance due to excellent thermal and electrical conductivity.

Structure of Lithium Fluoride

The cubic structure of lithium fluoride’s ionic crystal alternates between lithium and fluoride ions, with a dense lattice constant of approximately 3.01 Å, attributing to its significant hardness.

Other Information on Lithium Fluoride

Production Method of Lithium Fluoride

Lithium fluoride is typically produced by reacting water-soluble lithium salts (e.g., lithium sulfate, carbonate, nitrate, or chloride) with hydrofluoric acid. The reaction, exemplified with lithium sulfate as Li2SO4 + HF → LiF↓ + LiHSO4, precipitates lithium fluoride, which is then filtered, washed, and dried to yield the powdered form.

What Is Magnesium Fluoride?

Magnesium fluoride is an inorganic compound with the formula MgF₂. It is known by its CAS number 7783-40-6. Occurring naturally in small quantities as the mineral serratite, magnesium fluoride is a rare mineral. It can irritate the skin and eyes and is harmful if ingested.

Uses of Magnesium Fluoride

As a material with a low refractive index, magnesium fluoride is extensively used for anti-reflective coatings. By depositing magnesium fluoride films on lenses and prisms, the reflection of light can be minimized. Its applications extend to antireflective coatings, multilayers, beamsplitters, polarizing films for LCDs, and glass coatings.

Magnesium fluoride’s single crystals, notable for their ease of processing and wide transmission wavelength range (0.11-7.5 μm), find use as materials for ultraviolet region deflecting elements, optical substrates, window plates, and lenses. They are also utilized in the manufacturing of optical fluoride lenses for digital SLR cameras and scintillators and as base materials for optical fibers.

Properties of Magnesium Fluoride

With a molecular weight of 62.30, magnesium fluoride is a white powdery solid at room temperature, melting at 1,248°C and boiling at 2,260°C. It has a density of 3.15 g/mL and is insoluble in water and ethanol, slightly soluble in nitric acid, but not in dilute hydrochloric acid. It efficiently transmits electromagnetic waves in the 0.11~7.5 μm range and is durable against heat and shock. While stable under typical storage conditions, it should be kept away from strong oxidizers, extreme heat, and direct sunlight to prevent decomposition into halides and metal oxides.

Types of Magnesium Fluoride

Available mainly for research and industrial applications, magnesium fluoride is sold in various sizes suitable for laboratory use (e.g., 5g, 25g, 100g, 500g) and is ideal for vacuum evaporation techniques. Industrially, it is used in optical thin films and as a material for transparent, low-refractive index coatings, classified under rare metals. It is supplied in larger quantities, such as 20 kg bags, for factory use, appearing in white to transparent, granular, or tablet forms.

Other Information on Magnesium Fluoride

1. Synthesis of Magnesium Fluoride

Magnesium fluoride can be synthesized by reacting magnesium oxide with a hydrogen fluoride source, such as ammonium hydrogen fluoride.

2. Crystal Structure of Magnesium Fluoride

Its crystal structure is rutile-type, belonging to the tetragonal crystal system, similar to TiO₂. The structure features an octahedral coordination of six F atoms around each Mg atom and a triangular coordination of three Mg atoms around each F atom. In its gaseous form, MgF₂ exhibits a linear molecular structure.

What Is Barium Fluoride?

Barium fluoride is an ionic compound consisting of barium and fluoride ions, represented by the formula BaF₂.

Its CAS registration number is 7787-32-8. It appears as a white powder at room temperature and pressure. Fluoride crystals are known for their ability to transmit infrared rays, with barium fluoride standing out for its wide range of transmitted wavelengths.

Due to this, it is used in manufacturing lenses and infrared glass. Barium fluoride is classified as a hazardous chemical and as a deleterious substance.

Uses of Barium Fluoride

Barium fluoride is utilized in high-purity aluminum smelting, as a flux for welding rods, and in glazes. It transmits a broad spectrum of electromagnetic waves, from ultraviolet to infrared (wavelengths from about 0.15 to 14 μm).

Its applications include lenses and prisms for a wide range of wavelengths, window plates in infrared spectroscopy, and scintillators in X-ray detection. It is also used in optics for digital SLR cameras, as a base material for optical fibers, cell windows for NDIR gas measurement, observation windows for temperature measurement in radiation thermometers and infrared cameras, and protective windows for mid-infrared camera lenses.

Among fluoride crystals, barium fluoride transmits the widest range of wavelengths and is more resistant to high-energy electromagnetic waves than calcium fluoride and other fluorides.

Properties of Barium Fluoride

Barium fluoride, with a molecular weight of 175.324, melts at 1,253 °C and boils at 2,260 °C. It is an odorless white solid at room temperature. With a density of 4.893 g/mL and a solubility in water of 1.58 g/L at 10 °C, it is almost insoluble in water.

It remains stable under normal handling conditions but is sensitive to sudden heating and shock. Storage in a cool, dark place away from direct sunlight is recommended.

It reacts with oxidizing and reducing agents. Although nonflammable, it can decompose into highly toxic hydrogen fluoride gas in a fire.

Types of Barium Fluoride

Barium fluoride is available mainly as reagent-grade products for research and development and as raw materials for industrial use. For R&D purposes, it comes in convenient sizes like 20g, 50g, 100g, and 500g. These products are typically stable at room temperature.

For industrial applications, particularly in glass and lens manufacturing, it is supplied in larger quantities, such as 20 kg bags, for easy handling in factories.

Other Information on Barium Fluoride

1. Barium Fluoride in Nature

Barium fluoride occurs naturally as frankdixonite, found in the Carlin gold deposit in Eureka County, Nevada, alongside quartz.

2. Crystal Structure of Barium Fluoride

At room temperature and pressure, barium fluoride has a structure similar to CaF₂, but under high pressure, it adopts a structure akin to PbCl₂.

3. Safety and Hazard Information of Barium Fluoride

Barium fluoride is recognized for several hazards:

• Toxic if swallowed
• Causes serious eye irritation
• May cause respiratory irritation
• Potential risk of harm to the cardiovascular, nervous, muscular systems, kidneys, and bones from long-term or repeated exposure

Given these hazards, it is regulated under various laws and classified as a deleterious substance and as a hazardous chemical. It is also classified under environmental protection laws, emphasizing the need for careful disposal. Despite being nonflammable, it is regulated under fire service laws due to the potential generation of hydrogen fluoride gas during combustion.