月: 2023年4月

What Is Cysteamine?

Cysteamine, a white, water-soluble solid with an unpleasant odor, features both amine and thiol functional groups. With the chemical formula HSCH₂CH₂NH₂, it is known as 2-aminoethanethiol and has a molecular weight of 77.15 (CAS No. 60-23-1). It’s typically handled as its hydrochloride salt, which appears as white to light brown crystals. Discovered in the 1950s, cysteamine was first approved in the United States in 1994 for treating cystinosis.

Uses of Cysteamine

Cysteamine is used in pharmaceuticals to treat cystinosis by cleaving cystine’s disulfide bonds. In radiotherapy, it serves as a radical scavenger. Additionally, it is used in cosmetics for skin whitening and perm solutions, acting as a reducing agent for hair’s cystine bonds, though its application requires careful formulation to mitigate oxidation and odor.

Properties of Cysteamine

Boasting a melting point of 98°C, Cysteamine decomposes before boiling and is highly soluble in water, methanol, and ethanol. It plays a crucial role in treating cystinosis and can aid in synthesizing glutathione, a potent antioxidant important for detoxifying cells.

Other Information on Cysteamine

1. Manufacturing Method of Cysteamine

Cysteamine is produced through the hydrolysis of 2-(2-aminoethylthio)thiazoline dihydrochloride, a process involving chloroethylamine hydrochloride and mercaptothiazoline.

2. Regulatory Information

Though exempt from many major domestic regulations, cysteamine is classified as acutely toxic under the GHS classification, necessitating careful handling.

3. Precautions for Handling and Storage

Storage and handling precautions include keeping the container tightly closed in a dry, cool place, using personal protective equipment, and ensuring proper ventilation to avoid inhalation.

What Is Cyclopentene?

Cyclopentene is an organic compound, a cycloalkene with the chemical formula C₅H₈, known for its presence as an impurity in gasoline, typically in concentrations of 1% or less. Its CAS registration number is 142-29-0.

Uses of Cyclopentene

Primarily used in chemical synthesis, cyclopentene acts as a starting monomer for producing various plastics and rubber materials, including cyclopentene rubber through ring-opening metathesis polymerization. It’s also a precursor for neplanocin A, a compound with noted anticancer and antiviral properties.

Properties of Cyclopentene

Figure 1. Basic Information on Cyclopentene

Cyclopentene is a colorless liquid at room temperature with a pungent, mildly sweet odor, boasting a molecular weight of 68.11, and exhibiting a boiling point of 44°C. It is soluble in common organic solvents like ethanol and benzene, highly flammable with a flash point of -29°C, and has a spontaneous combustion temperature of 395°C.

Types of Cyclopentene

Available for both research and industrial applications, cyclopentene is sold in various volumes for R&D, commonly refrigerated, and in larger quantities like 130 kg drums for industrial use, particularly as a monomer.

Other Information on Cyclopentene

1. Synthesis of Cyclopentene

Figure 2. Synthesis of Cyclopentene

The synthesis of cyclopentene includes methods like the pyrolysis of naphtha and catalytic hydrogenation of cyclopentadiene. Important chemical reactions involving cyclopentene include polymerization using Ziegler-Natta catalysts and hydrocarboxylation with palladium catalysts to produce cyclopentanecarboxylic acid.

2. Chemical Reactions of Cyclopentene

Figure 3. Hydrocarboxylation reaction of Cyclopentene

When cyclopentene is polymerized using a Ziegler-Natta catalyst, the 1,3-polymerization reaction is known to occur. Hydrocarboxylation of cyclopentene with palladium catalyst yields cyclopentanecarboxylic acid.

3. Hazards of Cyclopentene

Cyclopentene, as mentioned above, is a highly flammable substance and is designated by the GHS classification as follows

• Inflammable liquid: Category 2
• Self-reactive chemical: Type G

Keep away from ignition sources such as heat, sparks, open flames, and high temperatures. When handling, it is also important to wear appropriate personal protective equipment such as protective gloves, safety glasses, and protective masks, and to provide an appropriate environment by using explosion-proof electrical equipment, ventilation equipment, and lighting equipment.

Tools that do not generate sparks should be used, and precautions against electrostatic discharge should be taken. The product must be stored in a well-ventilated area and kept in a cool place.

4. Regulatory Information on Cyclopentene

Cyclopentene is a regulated compound by law due to the hazards mentioned above. It must be handled properly in compliance with laws and regulations.

What Is Cyclopentanone?

Cyclopentanone, represented by the chemical formula (CH2)4CO, is a cyclic ketone with a five-membered ring structure. It is a colorless liquid with a characteristic odor, similar to that of methyl methacrylate, and is known for its volatility.

With a molecular weight of 84.12 g/mol, a density of 0.95 g/cm³, a melting point of -58.2 °C, a boiling point of 130.6 °C, and CAS number 120-92-3, cyclopentanone is used across various industries.

Uses of Cyclopentanone

Cyclopentanone serves as a synthetic intermediate in the manufacturing of pharmaceuticals, pesticides, rubber chemicals, and electronic materials, including as a solvent in wafer manufacturing. It’s integral in the synthesis of plant-derived substances like jasmonic acid, a phytohormone involved in plant stress responses and growth processes.

1. Raw Material for Plant-Derived Substances

As a critical component in various plant hormones and substances, cyclopentanone’s derivatives, such as jasmonic acid, play roles in fruit ripening, senescence, and stress tolerance. These substances are synthesized within and transported across plant tissues, aiding in environmental adaptability and defense mechanisms.

2. Raw Material for Flavors and Fragrances

Cyclopentanone derivatives are key in creating fragrances, contributing to the aromatic qualities of perfumes and other scented products. These derivatives include methyl dihydrojasmonate and magnolione, among others.

3. Metal Cleaning Agent

Utilized in metal cleaning, cyclopentanone effectively removes oils, waxes, and flux residues. Its favorable properties, such as a low boiling point and excellent biodegradability, make it a preferred choice in electronic material production and metalworking.

Properties of Cyclopentanone

Produced through the dehydrogenation of cyclopentanol or ketonization of adipic acid, cyclopentanone is miscible with various organic solvents. Despite its utility, it’s used less frequently as a solvent compared to alternatives due to its flammability and specific handling requirements.

Other Information on Cyclopentanone

Hazards of Cyclopentanone

Classified under the GHS as a flammable liquid and an acute eye irritant, cyclopentanone requires careful handling and storage. Protective measures, including eyewear, lab coats, and gloves, are essential when working with this substance.

What Is Cyclopentadiene?

Cyclopentadiene is a cyclic diene with the molecular formula C5H6. It is a colorless liquid, characterized by its terpene-like odor. Industrially, it is obtained through the fractional distillation of gas oil from coal dry distillation and the C5 fraction from naphtha pyrolysis. At room temperature, it is highly reactive and tends to dimerize to form dicyclopentadiene.

In laboratory settings, cyclopentadiene is often generated from dicyclopentadiene by heating, which causes it to decompose back into cyclopentadiene. This process allows for controlled use of the substance in various applications.

Under the GHS classification, cyclopentadiene is categorized as a flammable liquid, with acute toxicity, eye irritation potential, and specific target organ toxicity for both single and repeated exposure.

Uses of Cyclopentadiene

Cyclopentadiene is utilized in the synthesis of various products including pesticides, insecticides, and resin plasticizers. Its active covalent double bond makes it a valuable compound in chemical reactions. Significant applications include:

• Production of himic anhydride through the Diels-Alder reaction with maleic anhydride.
• Synthesis of ethylidene norbornene, a raw material for EPDM synthetic rubber.
• Manufacturing hexachlorocyclopentadiene, used in doline-based agricultural chemicals and insecticides.

These compounds are derived from cyclopentadiene and highlight its importance in industrial chemistry.

What Is Cyclopropenylidene?

Cyclopropenylidene, with the chemical formula C3H2, is a highly reactive organic compound. It is characterized by a C=C double bond within a ring structure, where one carbon atom possesses a lone electron pair. Due to its reactivity, cyclopropenylidene exists on Earth only under specific laboratory conditions.

This compound is notable as an interstellar substance, being one of the rare materials found in interstellar space, or interstellar matter (ISM). A related compound, propadien-1-ylidene radical (also with the formula C3H2), shares this distinction as an interstellar material.

Uses and Significance of Cyclopropenylidene

Given its extreme reactivity, cyclopropenylidene does not have direct industrial or biochemical applications on Earth. However, it garners significant interest in the field of planetary science.

In 2020, cyclopropenylidene was detected in the atmosphere of Saturn’s moon Titan, marking a significant discovery. Previously, it had only been identified in interstellar molecular clouds. This detection on Titan suggests that cyclopropenylidene may contribute to the formation of complex compounds that could potentially support life or prebiotic conditions on this moon.

What Is Cyclooctatetraene?

Cyclooctatetraene (COT), with the molecular formula C8H8, is a cyclic unsaturated hydrocarbon, and a member of the annulenes, specifically [8]annulene. Its CAS number is 629-20-9. This compound, a colorless or pale yellow liquid at room temperature, is known for its distinct odor and is insoluble in water but soluble in organic solvents like ether, benzene, and ethanol.

With a molecular weight of 104.149, COT has a melting point of -3 °C and a boiling point of 143 °C. It is slightly hygroscopic and gradually polymerizes in air.

Uses of Cyclooctatetraene

COT is used in the synthesis of organic films for silicon surfaces, liquid-state organic dye lasers, and as a triplet-state quencher. It’s a valuable synthetic intermediate for various cyclic compounds and raw material for chemicals like terephthalaldehyde and phenylacetaldehyde.

Synthesis and Chemical Properties of Cyclooctatetraene

1. Synthesis of Cyclooctatetraene

COT is synthesized via Reppe synthesis, involving the polymerization of acetylene in tetrahydrofuran using nickel cyanide as a catalyst under high pressure. It was first synthesized from natural pelletierine by Richard Willstätter in 1912.

2. Chemical Properties of Cyclooctatetraene

COT is an 8π electron system and is non-aromatic, as it doesn’t adhere to the Hückel rule for aromaticity. It adopts a boat conformation and is reactive to addition, rearrangement, and oxidation reactions. Interestingly, reactions like those with potassium can convert COT from non-aromatic to aromatic, forming a dianion that satisfies the Hückel rule.

Types and Storage of Cyclooctatetraene

COT is primarily used as a research reagent and is available in small quantities, typically sold in glass bottles and requiring refrigerated or frozen storage. It often contains a small percentage of polymerization inhibitors like hydroquinone due to its propensity to polymerize.

Related compounds like cyclooctatetraene iron tricarbonyl, where COT acts as an iron ligand, are also marketed for research and development purposes.

What Is Cyanic Acid?

Cyanic acid, with the molecular formula HOCN and a molecular weight of 43.025, is known for its isomeric structures, isocyanic acid (H-N=C=O), and fulminic acid (HO-N=C:). It exists as a liquid or gas at room temperature, with a boiling point of 23.5°C, and has an odor similar to acetic acid. Slightly soluble in water, it is a slightly stronger acid than acetic acid.

Cyanic acid is produced by heating cyanuric acid in an inert gas atmosphere and rapidly cooling and collecting the resulting gas.

Uses of Cyanic Acid

Cyanic acid’s cyano group makes it a valuable starting material in the synthesis of biologically important organic compounds. Its uses include:

• Synthesis of inorganic cyanides, such as sodium cyanide.
• Production of chemicals like methyl methacrylate, hexamethylenediamine, lactic acid and its esters, alpha-amino acids, and polyamino carboxylic acids like EDTA (ethylenediaminetetraacetic acid).
• Use in insecticides.

Historically, hydrogen cyanide, a related compound, has been used as a chemical weapon and insecticide.

What Is Cyanamide?

Cyanamide, also known as amidocyanogen, cyanogenamide, carbamonitrile, or carbamic nitrile, is an amide derived from cyanogen.

Uses of Cyanamide

1. Pharmaceuticals

Cyanamide is utilized as a deterrent for alcohol consumption, promoting sobriety by causing unpleasant sensations upon alcohol intake. This effect is due to cyanamide’s inhibition of acetaldehyde breakdown, leading to its accumulation and the onset of symptoms like facial flushing, nausea, and dizziness. These adverse effects, appearing within five minutes and lasting up to 24 hours, discourage alcohol consumption.

Common side effects include nausea and headache. Immediate medical consultation is recommended for severe side effects such as skin disorders or liver function impairment.

2. Fertilizers

As a pesticide and fertilizer, the calcium salt of cyanamide enhances agricultural productivity. It gradually transforms into urea and ammonia, contributing to soil fertility with its insecticidal and fungicidal properties.

Properties of Cyanamide

Cyanamide, a colorless crystalline solid, has a molecular formula of CH₂N₂ and a molecular weight of 42.04. Notable for its solubility in polar solvents, cyanamide has a melting point of 45°C and a boiling point of 260°C. Its acid dissociation constant (pKa) of 10.3 indicates its strength as an acid.

Types of Cyanamide

Cyanamide and carbodiimide are related isomers, with cyanamide converting to dicyandiamide in basic solutions.

Other Information on Cyanamide

1. How Cyanamide Is Produced

Produced through various chemical reactions, including the action of water on calcium cyanamide or the reaction with acetic acid, cyanamide can be refined through recrystallization.

2. Regulatory Information

Cyanamide is subject to various national laws and regulations, including those related to poisonous substances and environmental management.

3. Handling and Storage Precautions

Mixing with strong oxidizers should be avoided, and protective measures should be taken to prevent skin irritation. In case of fire, appropriate extinguishing agents include carbon dioxide and water spray.

What Is Xylene?

Xylene is a clear, colorless, aromatic oily liquid with the chemical formula C₆H₄(CH₃)₂ and a molecular weight of 106.17. It’s known as dimethylbenzene and is pronounced “xylin” in both the United Kingdom and the United States. Xylene has three isomers: ortho, meta, and para, distinguished by their unique CAS numbers: 95-47-6, 108-38-3, and 106-42-3, respectively.

Uses of Xylenes

Xylenes serve various industrial applications, primarily in isomerization to ortho and para isomers for use in plasticizers and pigments for plastics. The meta isomer is a key raw material for isophthalic acid, contributing to polyester resin production. Para-xylene is used for terephthalic acid and dimethyl terephthalate, essential in plastics and clothing fibers. Mixed xylenes, produced with ethylbenzene, find applications in paints and thinners. Due to regulatory considerations, especially concerning ethylbenzene, careful handling is advised.

Properties of Xylenes

The melting points of xylene isomers vary, with -25 °C (-13 °F) for ortho, -48 °C (-54.4 °F) for meta, and 13 °C (55.4 °F) for para. Their boiling points are similarly close: 144 °C (291.2 °F), 139 °C (282.2 °F), and 138 °C (280.4 °F), respectively. Xylene is practically insoluble in water but dissolves in ether and ethanol, showcasing its utility as a solvent in various industrial processes.

Other Information on Xylene

1. Manufacturing Process of Xylene

Xylene is produced by methylation of toluene and benzene. The composition of commercial or laboratory-grade xylene typically includes a significant portion of o-xylene, with m-xylene, p-xylene, and ethylbenzene also present. Advanced methods allow for adjusting isomer ratios to favor high-value p-xylene.

2. Reaction of Xylene

Xylene undergoes reactions involving both methyl groups and ring C-H bonds, leading to products used in various chemical processes, including the production of dicarboxylic acids, dinitriles, and compounds used in tear gas.

3. Legal Information and Handling Precautions

Under multiple laws and regulations, xylene is classified as a hazardous substance, requiring specific labeling and precautions during handling and storage. It is imperative to use protective gear and ensure proper ventilation when working with xylene to prevent health risks.