月: 2023年1月

What Is Strontium?

Strontium, symbol Sr, is an alkaline earth metal with an atomic number 38 and an atomic weight of 87.62. This silvery-white metallic element is highly reactive, violently reacting with water and tarnishing in air. Its salts are used to produce red colors in fireworks due to their striking red flame coloration.

Uses of Strontium

Strontium’s primary applications include serving as an additive for display and photovoltaic glass, manufacturing ferrite magnets, ceramic capacitors, and rust inhibitors. It also plays a role in producing red colors for fireworks and smoke bombs through its nitrates.

Properties of Strontium

Similar to calcium in its physiological behavior, strontium has a melting point of 777°C and boils at 1,382°C. It forms a grayish-white oxide layer when exposed to air and reacts explosively with water. Strontium can be obtained by reducing its oxide with aluminum or by electrolysis of strontium chloride.

Structure of Strontium

At room temperature, strontium adopts a face-centered cubic lattice structure. It transitions to hexagonal close-packed from 213°C to 621°C and to body-centered cubic from 621°C to 769°C. Its electron configuration is [Kr] 5s², allowing it to substitute calcium in minerals.

Other Information on Strontium

1. Production of Strontium

China, Spain, and Mexico lead in strontium production, primarily extracting it from the mineral celestite (SrSO₄). The extraction process often involves converting celestite to strontium carbonate, which is then utilized in various applications.

2. Isotopes of Strontium

Natural strontium consists of four stable isotopes, with ⁸⁸Sr being the most abundant. The radioactive ⁹⁰Sr, with a half-life of 28.78 years, is noteworthy for its use in radioisotope thermoelectric generators. Strontium isotopes have significant applications in geology and nuclear science.

What Is Dichloromethane?

Dichloromethane (DCM), also known as methylene chloride or methylene dichloride, is a colorless liquid noted for its strong, sweet aroma. It may cause mild irritation or chemical injury upon skin contact. Due to its anesthetic vapor, inhaling large quantities quickly can lead to acute poisoning, necessitating caution during use. DCM is produced by chlorinating methyl chloride or by reducing chloroform with zinc and acetic acid.

Uses of Dichloromethane

Dichloromethane finds broad industrial applications as a refrigerant, cleaning agent for metal equipment and printed circuit boards, foaming aid for urethane, paint stripper, and aerosol propellant. It is a preferred solvent for organic substances due to its low boiling point and high purity requirements. Additionally, dichloromethane is used in manufacturing polycarbonates, pharmaceuticals, agrochemicals, and precision analysis like liquid chromatography.

It is favored over other halogenated hydrocarbons due to its nonflammability, lower toxicity, and as an alternative to trichloroethylene.

Properties of Dichloromethane

With a chemical formula of CH₂Cl₂, DCM’s structure consists of two chlorine atoms replacing two hydrogen atoms in methane. It has a density of 1.3266 g/cm³, a melting point of -96.7°C, and a boiling point of 40°C. Dichloromethane is notable for its heavier density compared to water, aromatic odor, and excellent solubility in ethanol and diethyl ether, though it is somewhat insoluble in water. It dissolves a vast array of organic compounds.

Other Information on Dichloromethane

1. Synthesis of Dichloromethane

Dichloromethane is industrially produced through a radical reaction between methane or methyl chloride and chlorine gas at 400-500°C. This process yields a mixture including chloromethane, dichloromethane, trichloromethane (chloroform), and tetrachloromethane (carbon tetrachloride), from which DCM can be purified by distillation.

2. Purification of Dichloromethane

For organic synthesis, dehydration with a molecular sieve generally suffices. For precision work, distillation with calcium hydride as a drying agent is recommended, avoiding sodium to prevent explosive reactions.

3. How to Store Dichloromethane

Though stable, highly purified dichloromethane can decompose oxidatively when exposed to oxygen or light, producing harmful byproducts like hydrogen chloride or phosgene. To minimize this risk, stabilizers such as alcohols, olefins, and amines are added, and the substance should be stored in tightly sealed, light-protected containers.

What Is Diethylenetriamine?

Diethylenetriamine is an organic compound with the chemical formula C₄H₁₃N₃ and structural formula HN(CH₂CH₂NH)₂. It falls under the category of primary amines and is known by several names, including 2,2′-iminodiethylamine, 2,2′-diaminediethylamine, and bis(2-aminoethyl)amine. Its CAS number is 111-40-0.

Chemically akin to ethylenediamine, it finds use in similar applications. The molecular structure is often compared to that of diethylene glycol.

Uses of Diethylenetriamine

Diethylenetriamine is utilized in various applications, such as paper wetting and strengthening agents, epoxy resin curing agents, chelating agents, ion exchange resins, fiber treatment agents, and the synthesis of synthetic organic materials. Among these, its most significant use is as a paper wet strengthener.

This compound is integral to the production of polyamide resins through the reaction with adipic acid, further treated with epichlorohydrin. As a fiber treatment agent, it is used in anti-wrinkle agents, surfactants, and dye-fixing agents.

Additionally, it serves roles in agrochemicals as a fungicide, insecticide, and herbicide, and is notably used in epoxy resin-based adhesives and curing agents for thermosetting resins, facilitating cross-linking through reaction with epoxide groups.

Properties of Diethylenetriamine

Figure 1. Basic Information on Diethylenetriamine

With a molecular weight of 103.17, diethylenetriamine has a melting point of -39.0°C and a boiling point of 204.1°C. At room temperature, it appears as a colorless to yellow viscous liquid and emits an amine odor.

It exhibits high solubility in water, ethanol, and acetone, and is soluble in polar solvents but insoluble in simple hydrocarbons. Its density is 0.955 g/mL. Being a weak base, its aqueous solutions display weak alkalinity.

Types of Diethylenetriamine

Available primarily for research and development, diethylenetriamine is sold in various volumes, including 5mL, 25mL, 100mL, 1L, 2.5L, and 18L, accommodating both laboratory use and larger-scale applications affordably.

Other Information on Diethylenetriamine

1. Synthesis of Diethylenetriamine

Figure 2. Synthesis of Diethylenetriamine

Diethylenetriamine can be synthesized by reacting 1,2-dichloroethane with ammonia, or monoethanolamine with ammonia under hydrogenated catalysts. Industrially, it is primarily obtained as a byproduct in the production of ethylenediamine from 1,2-dichloroethane.

2. Chemical Reaction of Diethylenetriamine

Figure 3. Reaction of Diethylenetriamine with Epoxide Groups

It reacts with epoxide groups to form N-alkylated crosslinks, a reaction pivotal in the use of curing agents for epoxy resin adhesives. Diethylenetriamine also acts as a tridentate ligand in coordination chemistry, forming complexes with metals such as in Co(Dien)(NO₂)₃.

3. Toxicological Information on Diethylenetriamine

Recognized as a hazardous substance, diethylenetriamine exhibits various toxicity levels under the GHS classification, including acute toxicity (oral, dermal, inhalation), skin corrosion/irritation, serious eye damage/eye irritation, respiratory and skin sensitization, and reproductive toxicity.

4. Regulatory Information on Diethylenetriamine

Due to its hazardous properties, diethylenetriamine is subject to regulatory oversight under various laws.

What Is Diisopropyl Ether?

Diisopropyl ether (DIPE), also known as isopropyl ether, is an organic compound with the molecular formula C₆H₁₄O and the specific structure (CH₃)₂CH₂O. It has a CAS number of 108-20-3. This clear, colorless liquid is characterized by its odor and has a molecular weight of 102.17, a melting point of -60°C, and a boiling point of 68°C. Its density is 0.725 g/mL, and it is extremely soluble in ethanol and diethyl ether but insoluble in water.

Due to its high flammability and low flash point of -6.7°C, diisopropyl ether is classified under strict safety regulations.

Uses of Diisopropyl Ether

Diisopropyl ether is utilized as an extraction solvent in the processing of animal and vegetable oils, mineral oils, waxes, and resins. It also finds applications in pharmaceuticals, fragrance extraction, and the recovery of various acids from aqueous solutions. As a general solvent, it is involved in producing collodion solution, smokeless gunpowder, and rubber cement. Furthermore, it acts as a synthetic raw material in dye manufacturing and serves as an anti-knocking agent in gasoline when mixed with isooctane.

Properties of Diisopropyl Ether

1. Synthesis of Diisopropyl Ether

Diisopropyl ether is primarily synthesized from isopropyl alcohol through reactions with inorganic acids or via the Williamson ether synthesis. It can also be a byproduct in isopropanol production through propylene hydration.

2. Chemical Properties of Diisopropyl Ether

Exposure to light and air can significantly affect diisopropyl ether, leading to the potential formation of explosive peroxides over time. Stabilizers like hydroquinone are often added to prevent peroxide formation. Due to these safety concerns, methyl tertiary butyl ether may be used as a safer alternative in some applications.

Types of Diisopropyl Ether

Diisopropyl ether is available as both R&D reagents and industrial chemicals, with packaging options ranging from small laboratory sizes to large containers suitable for industrial use. Hydroquinone may be added as a stabilizer in certain products to enhance safety during storage and handling.

What Is Silicon Carbide?

Silicon carbide (SiC) consists of silicon (Si) and carbon (C). It is not found naturally on Earth, but rather in meteorites. Due to its high hardness and wear resistance, it is extensively utilized in abrasives and refractory materials. While pure silicon carbide is colorless and transparent, it is typically black when used industrially.

High-purity silicon carbide is notably gaining traction as a superior material for power semiconductors, aimed at outperforming traditional silicon semiconductors.

Applications of Silicon Carbide

Characterized by its high hardness, wear resistance, thermal conductivity, and corrosion resistance, silicon carbide is ideal for use in mechanical seals, shafts, and other sliding parts. It also serves in the manufacture of classifier and crusher parts, as well as in heat-resistant components like high-temperature test equipment and metal-melting crucibles.

In addition, SiC power semiconductors are employed in hybrid electric vehicles (HEV).

Properties of Silicon Carbide

Silicon carbide is insoluble in water, sublimating at 2,545°C, and thermally decomposing at temperatures above 2,800°C. It ranks 9.5 on the Mohs hardness scale, making it second only to diamond and boron carbide. Its large refractive index of 2.65 allows large crystals to have mirror-like reflectivity.

Although pure silicon carbide is transparent, industrial variants are green or black, with the color fading as the purity increases. Impurities such as aluminum and nitrogen in the crystal lattice account for its coloring. Green silicon carbide, due to its higher electrical resistance, is often used in heating elements.

As silicon atoms are larger than carbon atoms, the interatomic distance in SiC is greater than in carbon, resulting in lower thermal conductivity and increased softness.

Structure of Silicon Carbide

Silicon and carbon in silicon carbide are covalently bonded, yet exhibit ionic characteristics due to their differing electronegativity, stabilizing as a 1:1 compound. Its molar mass is 40.097 g/mol, with a density of 3.22 g/cm³.

Atoms are tetrahedrally arranged around each other, with over 200 varieties based on the layer structure’s repetition pattern. Primarily, there are two types: alpha (hexagonal) and beta (cubic).

α-Type silicon carbide powder can be produced by heating coke and silica stone above 2,100°C in an electric furnace, while β-type is obtained by heating carbon black and silicon to 1,800°C in an argon atmosphere.

Other Information on Silicon Carbide

1. History of Silicon Carbide

In 1891, Edward Goodrich Acheson in the US synthesized silicon carbide by heating a coke and clay mixture with a carbon arc lamp, leading to the establishment of Carborundum Abrasives Co. and the industrial production of what is sometimes known as carborundum.

In 1905, Ferdinand Frédéric Henri Moissan discovered silicon carbide in a meteorite in Arizona, where it is also referred to as Moissanite in mineralogy.

2. Reactions of Silicon Carbide

Chemically inert, silicon carbide is insoluble in water, acids, and alkalis, and does not react with aqua regia or concentrated nitric acid. It remains unreactive towards N₂, H₂, or CO, but oxidizes at temperatures above 800°C in air, forming a protective SiO₂ layer that slows further oxidation. It reacts with Cl₂ above 800°C, producing C and SiCl₄.

What Is L-Cysteine?

Figure 1. Basic Information on L-Cysteine

L-cysteine is a nonessential amino acid characterized by a thiol group on its side chain.

Its abbreviation is Cys, and L-cysteine is the naturally occurring form. It plays a role in reducing the production of melanin, which causes skin pigmentation, and promotes its elimination from the body.

L-cysteine, being a constituent of proteins, reacts with acetaldehyde, a primary cause of hangovers, neutralizing its toxicity. Its effectiveness in mitigating hangovers has led to its use in health supplements.

Uses of L-Cysteine

L-cysteine is used in pharmaceuticals and as a food additive. It exhibits antioxidant properties in the body and aids in liver detoxification.

Its applications include use in anti-allergic medications, treatments for skin conditions, and as a countermeasure against leukopenia resulting from radiation exposure. It is also valued in cosmetic supplements for its skin-lightening effects when combined with vitamin C.

Additionally, it is popularly employed as a remedy for hangovers.

Properties of L-Cysteine

L-cysteine, a protein-building amino acid, is glycogenic. It exhibits specific optical rotation [α]D of +9.4° and decomposes at 240°C.

The thiol group in L-cysteine serves as a nucleophilic catalyst and displays high reactivity. The pKa of this group is around 8, varying with environmental conditions.

Structure of L-Cysteine

Figure 2. Structure of L-Cysteine

L-cysteine is 2-amino-3-sulfanyl propionic acid, considered hydrophobic or having a neutral polar side chain.

Due to its chiral carbon atom, it exists as R-cysteine (L-cysteine) and S-cysteine (D-cysteine). By the rank order rule, L-cysteine uniquely assumes the R configuration. Its chemical formula is C₃H₇NO₂S with a molar mass of 121.16 g/mol.

Other Information on L-Cysteine

1. Biosynthesis of L-Cysteine

Biosynthesis in animals begins with serine, converting methionine to homocysteine, then to cystathionine via cystathionine β-synthetase, and finally to L-cysteine.

In plants and bacteria, L-cysteine is synthesized from serine through O-acetylserine, with cysteine synthase facilitating the final step.

2. Oxidation of L-Cysteine

Figure 3. Disulfide Bonds in L-Cysteine

L-cysteine forms cystine upon oxidation, which involves the linkage of two L-cysteine molecules via a disulfide bond.

This oxidized form, referred to as cystine, loses its nucleophilic properties.

3. Biochemistry of L-Cysteine

L-cysteine’s thiol group facilitates protein cross-linking via disulfide bonds, crucial for the stability and functional integrity of proteins both inside and outside the cell.

For instance, insulin’s structure and function are dependent on disulfide bonds between L-cysteine residues, demonstrating its significance in biochemistry.

What Is Cyclopentane?

Cyclopentane, a clear and colorless liquid with a characteristic odor, is an organic compound with the chemical formula C₅H₁₀. It features a molecular weight of 70.13 and is registered under CAS No. 287-92-3. Notable for its low solubility in water and high solubility in ethanol and acetone, cyclopentane has distinct physical properties, including a melting point of -94°C and a boiling point of 49°C.

Uses of Cyclopentane

Cyclopentane serves various industrial applications, ranging from a foaming agent in insulation materials to an additive for high-octane gasoline, enhancing engine efficiency by improving the fuel’s octane number. It is also utilized in azeotropic distillation as a solvent to separate complex mixtures, owing to its ability to form new azeotropic mixtures with lower boiling points than the original substances.

1. Foaming Agent

As a solvent and foaming agent, cyclopentane is integral in producing rigid polyurethane foam for housing insulation, offering energy efficiency improvements.

2. High-Octane Gasoline

When added to gasoline, cyclopentane reduces exhaust toxins and boosts the octane number, reducing engine knock and enhancing engine performance.

3. Solvent for Azeotropic Distillation

In azeotropic distillation, cyclopentane helps separate mixtures that cannot be distilled by conventional means, by creating a new azeotropic mixture with a lower boiling point.

Properties of Cyclopentane

Cyclopentane is a cycloalkane with a pentagonal skeletal structure, representing a class of cyclic saturated hydrocarbons known for their stability due to minimal angular strain in their bond angles. This stability contrasts with smaller cycloalkanes like cyclopropane and cyclobutane, which exhibit significant angular distortion and chemical instability.

1. Structure of Cyclopentane

With a general formula of (CH₂)_n, cyclopentane’s pentagonal structure ensures nearly ideal bond angles close to 109°, contributing to its chemical stability despite torsional strain.

2. Stability of Cyclopentane

Cyclopentane’s bond angle of 108° minimizes angular strain, making it chemically stable compared to cyclopropane and cyclobutane, which are prone to bond breakage due to their distorted bond angles.

Other Information on Cyclopentane

1. Comparison with Pentane

While sharing similar physical and chemical properties with pentane, a chain alkane, cyclopentane’s cyclic structure imparts unique characteristics, including flammability and reactivity under specific conditions.

2. Legal Information

Recognized as a highly flammable substance, cyclopentane is regulated under various safety and environmental protection laws, highlighting the importance of careful handling and storage to mitigate risks.

What Is Sodium Cyanide?

Sodium cyanide is a white, water-soluble solid with the chemical formula NaCN. It has a molecular weight of 49.0072 and is identified by CAS number 143-33-9. Sodium cyanide reacts with acids to produce highly poisonous hydrogen cyanide gas (HCN).

Properties of Sodium Cyanide

Sodium cyanide has a melting point of 564°C, a boiling point of 1,496°C, and a density of 1.595 g/cm³. It is easily soluble in water, ammonia, methanol, and ethanol, with its aqueous solution displaying strong alkalinity. Its solubility extends slightly to DMF and sulfur dioxide.

Uses of Sodium Cyanide

Sodium cyanide is utilized in metal plating, gold and silver metallurgy, organic synthesis, and the production of cyanide salts. In agriculture, its active ingredient quickly decomposes, preventing osmotic transfer to crops. Alkaline and copper cyanide baths, known for uniform electrodeposition, are applied in complex-shaped zinc and aluminum die-casting plating. Sodium cyanide’s high toxicity also aids in rapid specimen collection by entomologists.

Other Information on Sodium Cyanide

1. Manufacturing Process of Sodium Cyanide

Sodium cyanide production involves treating hydrogen cyanide with sodium hydroxide, ionizing it into cyanide and sodium ions. Historically, it was also prepared through the Kastner process, reacting sodium amide with carbon at high temperatures.

2. Reaction of Sodium Cyanide

The gold cyanide reaction, a key method for extracting gold from ores, leverages gold’s affinity for cyanide. This process produces sodium dicyanoferrate by oxidizing and dissolving gold with cyanide in the presence of air and water.

3. Regulatory Information

Sodium cyanide is regulated under various laws, and classified as a hazardous substance with specific handling and storage requirements to mitigate its toxic effects and environmental impact.

4. Handling and Storage Precautions

Handling and storage precautions include storing in cool, dark, ventilated areas, using protective gear, avoiding violent reactions with acids, and thorough cleaning after exposure. In case of inhalation or skin/eye contact, immediate actions such as seeking fresh air, washing with water, and obtaining medical attention are crucial.

What Are Cyanoacrylates?

Cyanoacrylates are a category of adhesives commonly used in instant adhesives. They include compounds like “methyl-2-cyanoacrylate” and “ethyl-2-cyanoacrylate.” These adhesives are typically colorless or pale yellow liquids with a characteristic odor and are insoluble in water but soluble in acetone.

Per the Hazardous Products Regulations (HPR), cyanoacrylates are classified under GHS as follows: Flammable liquids (Category 4), Skin irritation (Category 2), Eye irritation (Category 2A), and Specific target organ toxicity – single exposure (Category 3), affecting the respiratory system.

Uses of Cyanoacrylates

Cyanoacrylates are widely used for instant bonding in various applications, including joining plastics, rubber, and metals. They are utilized in both industrial and household settings. In medical applications, cyanoacrylates serve as wound-sealing agents.

These adhesives polymerize rapidly upon exposure to moisture adsorbed on surfaces or even in air, creating strong bonds quickly. While traditionally known for poor moisture and water resistance, recent advancements have led to the development of more water-resistant variants.

What Is Cyanide?

Cyanide refers to a group of compounds containing the cyanide ligand, represented by the CN group, also known as the cyano group. Cyanide compounds commonly include salts with cyanide ions as anions, such as potassium cyanide and sodium cyanide, which are known for their harmful effects on the human body.

Potassium cyanide, a typical example, is classified as acutely toxic, skin corrosive/irritant, eye irritant, and a specific target organ/systemic toxin under the GHS classification.

Uses of Cyanide

Cyanide is used in various industries due to its high toxicity. It serves as a fumigant for rodent infestations, an insecticide, and a fruit disinfectant. In plating and metallurgy, cyanide’s ability to form complexes with metals makes it a valuable component. Additionally, potassium cyanide and sodium cyanide are widely used in organic synthesis, where the cyano group is a versatile functional group, capable of being converted to carboxylic acids, amides, amines, and aldehydes.

Common reactions involving cyanide include those with alkyl halides using potassium cyanide and the Zandmeyer reaction using copper cyanide.