月: 2023年4月

What Is Hydantoin?

Hydantoin, also known as glycolylurea, is a compound synthesized by condensing glycolic acid and urea. It naturally occurs in molasses and appears as an odorless, colorless crystal under standard temperature and pressure. Hydantoin can be produced through Yurek’s hydantoin synthesis, involving amino acids, potassium cyanate, and hydrochloric acid. It serves as the foundational structure for various chemicals, including allantoin, phenytoin, and dantrolene. 

Uses of Hydantoin

Hydantoin and its derivatives have diverse applications:

1. Antiepileptic Drugs

Phenytoin, a derivative of hydantoin, is a widely used antiepileptic drug. It suppresses nerve cell excitability, reducing seizure occurrences.

2. Cosmetics and Skin Moisturizers

DialkylHydantoin derivatives, used in cosmetics and skincare, effectively retain skin moisture, alleviating dryness and irritation.

3. Ultraviolet Absorber

Hydantoin derivatives also act as UV absorbers in sunscreens and hair products, minimizing UV ray damage to skin and hair.

Additionally, these derivatives are crucial for producing agricultural chemicals and as intermediates in organic synthesis. PhenylHydantoin, derived from hydantoin, aids in amino acid identification due to its crystallinity. Heating hydantoin with barium hydroxide yields PhenylHydantoin, which can also be synthesized from various amino acids and phenyl isocyanate. Hydrolyzing hydantoin produces glycine, a basic amino acid, and substituting carbon at position 5 allows for the synthesis of various amino acids.

Properties of Hydantoin

Hydantoin (C₃H₄N₂O₂, molecular weight 100.09 g/mol) is a heterocyclic compound, known as imidazolidine-2,4-dione. Its structure results from the cyclic condensation of glycolic acid and urea. As a colorless crystalline solid, hydantoin is naturally found in molasses and has a melting point of 215-220°C. It is insoluble in water and slightly soluble in organic solvents like alcohol and ether.

Exhibiting cyclic amide properties, hydantoin can be reduced to amino acids and acts as the backbone for drugs such as phenytoin and sodium valproate, suppressing epileptic seizures by affecting the central nervous system. Its derivatives, formed through the condensation of urea and glyoxal, are used in skin moisturizers.

Structure of Hydantoin

Hydantoin features a five-membered cyclic structure with two nitrogen atoms and two carbonyl groups alternately attached to the ring. The nitrogen atoms are positioned at the 1st and 3rd positions, bonded to carbon atoms that have carbonyl groups at the 2nd and 4th positions.

This structure, exhibiting amide bond properties, is reactive under various conditions. Various hydantoin derivatives are produced by attaching different substituents, like phenyl groups in phenytoin, to the 5th carbon atom of the hydantoin ring, serving as antiepileptic drugs and skin moisturizers.

Other Information about Hydantoin

Method for Producing Hydantoin

Hydantoin synthesis includes:

1. Yurek’s Hydantoin Synthesis
This method synthesizes hydantoin derivatives from amino acids and potassium cyanate, where amino acids react with potassium cyanate under heat.

2. Bucherer-Berx Reaction
This method produces 5,5-disubstituted hydantoin derivatives from cyanohydrin and ammonium carbonate through carbamates and aldoximes reactions.

What Is Pantethine?

Pantethine is an organic compound, recognized as a dimer of pantetheine, connected through disulfide bonds. It serves a pivotal role in human physiology, similar to pantothenic acid (vitamin B5), from which it is derived.

The molecular formula for pantethine is C₂₂H₄₂N₄O₈S₂. Pantetheine, pantethine’s monomer, is an amide formed from pantothenic acid and cysteamine (2-mercaptoethylamine), showcasing similar biological activities to pantothenic acid. Pantethine’s CAS registration number is 137-08-6, highlighting its significance in scientific and health-related fields.

Uses of Pantethine

Pantethine mirrors the biological activities of pantothenic acid, making it a valuable component in nutritionally functional foods and medicinal products designed to prevent or treat pantothenic acid deficiency. Furthermore, it finds applications in cosmetics, acting as a key ingredient in hair and skin conditioning agents.

Pantothenic acid, or vitamin B5, is an essential nutrient involved in the metabolism of carbohydrates, fats, and proteins. It also promotes healthy intestinal motility and skin maintenance. Although dietary deficiencies are uncommon, supplementation with Pantethine can be beneficial in situations where the demand for pantothenic acid increases, such as during illness, pregnancy, or hyperthyroidism, as well as in managing conditions like hyperlipidemia, atonic constipation, and dermatological issues.

Properties of Pantethine

Pantethine has a molecular weight of 554.72 and boasts a boiling point of 987.2°C. It appears as a colorless to slightly yellow, clear viscous liquid at room temperature. Pantethine is soluble in water, methanol, and ethanol, though it degrades upon exposure to light. Its density is 1.28 g/mL.

Types of Pantethine

Pantethine is marketed for various uses, including in research, pharmaceuticals, and industry.

1. Reagent Products for Research and Development

As a reagent for R&D, pantethine is available as D-pantethine. These products come in quantities ranging from 50mg to 5g and require refrigeration or freezing for proper storage.

2. Pharmaceuticals

In pharmaceutical formulations, pantethine is utilized to prevent and treat pantothenic acid deficiencies. Available in forms such as tablets, powders, and injections, these products vary by manufacturer.

3. Industrial Use

Industrially, pantethine is sold in bulk, with quantities like 1kg and 25kg, for use as a synthetic material or intermediate in pharmaceuticals and other chemical productions.

Other Information about Pantethine

1. Pantethine, Pantetheine, Pantothenic Acid

Pantothenic acid, also known as vitamin B5, is a component of coenzyme A (CoA) and plays a critical role in carbohydrate and fatty acid metabolism. Pantetheine results from the condensation of pantothenic acid with cysteamine, forming an amide bond. Pantethine is then created through the oxidation and disulfide bonding of two pantetheine molecules.

These compounds are essentially identical in physiological function, acting in concert with CoA and 4′-phosphopantetheine as cofactors in vital metabolic processes.

2. Coenzyme A (CoA)

Coenzyme A is a vital coenzyme composed of pantothenic acid, adenosine diphosphate, and cysteamine. Its thiol group, derived from cysteamine, is capable of forming thioester bonds with various acyl groups, facilitating key metabolic reactions like the citric acid cycle and β-oxidation. CoA and its derivatives, such as acetyl-CoA, are central to numerous metabolic pathways, underscoring their importance in biological systems.

What Is Paraformaldehyde?

Paraformaldehyde, an organic compound, results from the dehydration and polymerization of formaldehyde. This linear polymer is recognized by its CAS registration number 30525-89-4 and has the chemical formula (CH₂O)_n. Also known as “paraform” and “1,3,5-trioxane,” paraformaldehyde belongs to the class of polymers known as polyacetals or polyoxymethylenes, characterized by the oxymethylene (-CH2O-) structure in their units. Due to its potent effects, it is regulated as a powerful drug under related laws, highlighting its significant toxicity.

Applications of Paraformaldehyde

As a versatile agent, paraformaldehyde is deployed as a fumigant for pest control and disinfection. Its high reactivity makes it a preferred raw material in the synthesis of various products, including paints, adhesives, preservatives, and resins (phenolic, urea, and vinylon acetalization applications), as well as in the production of ion exchange resins, pharmaceuticals, water-resistant glues, and protein glue coagulants. Specifically, it serves as a crucial ingredient for methylol and methylene compounds, which enhance the properties of paints and adhesives by providing UV protection and improving their durability and heat resistance. Notably, methylene chloride, a primary methylene compound, is widely used as a paint stripper and remover.

Properties of Paraformaldehyde

This polymer, denoted as (CH₂O)_n, appears as a white solid (in various forms like flakes, granules, or crystalline powder) and decomposes at temperatures between 120-180°C, depending on its polymerization degree. It emits a distinct formaldehyde odor and is insoluble in water, ethanol, and ether, yet dissolves in sodium hydroxide solution. Its density stands at 1.42g/mL. Notably, paraformaldehyde can revert to formaldehyde when dissolved in water or upon heating, highlighting its dynamic nature as it releases flammable formaldehyde gas when dried.

Types of Paraformaldehyde

Available for research and industrial applications, paraformaldehyde is often utilized as a crosslinking and immobilization reagent due to its ability to convert back to formaldehyde upon heating with sodium hydroxide. Its laboratory forms include manageable quantities like 100g, 500g, 1kg, and 2kg, facilitating easy handling. Industrially, it’s packaged in larger quantities, such as 20kg paper bags or flexible containers, supporting its use in manufacturing paints, adhesives, fiber processing resins, and phenolic resins.

Other Information about Paraformaldehyde

1. Generation of Paraformaldehyde

Paraformaldehyde naturally precipitates as a white solid from formaldehyde solutions, especially upon cooling. Formaldehyde, its monomer, is typically produced by the air oxidation of methanol in the presence of a catalyst or by the carbonization of calcium formate.

2. Paraformaldehyde Safety Information

Recognized as a flammable and combustible solid, paraformaldehyde poses risks of dust explosions when its particles are airborne. It can react vigorously with oxidizing agents, acids, and bases, potentially leading to the generation of heat or the release of formaldehyde gas. Its ingestion or inhalation is harmful, causing skin and eye irritation, along with possible lung damage.

3. Legal and Regulatory Information on Paraformaldehyde

Given its hazards, paraformaldehyde is subject to stringent regulations. It is classified as a combustible substance and is also designated as a deleterious substance under various health and safety laws. Compliance with these regulations is crucial for its safe handling and use.

What Is Papaverine?

Papaverine is an opium alkaloid used in medicine.

Its IUPAC name is 1-[(3,4-dimethoxyphenyl)methyl]-6,7-dimethoxyisoquinoline, also known as 6,7-dimethoxy-1-(3,4-dimethoxybenzyl)isoquinoline and Robaxapap.

Uses of Papaverine

Papaverine, present in opium at 0.8-1%, has a weaker central action and anesthetic effect compared to morphine. Its hydrochloride form relaxes visceral and vascular smooth muscles, alleviating abdominal pain by reducing tension in the gastrointestinal tract. It is effective for spasms related to gastritis, bile duct, and gallbladder diseases, and improves blood circulation by relaxing vascular smooth muscles, aiding in conditions like acute arterial and pulmonary embolisms, and circulation disorders.

Properties of Papaverine

With a chemical formula of C₂₀H₂₁NO₄ and a molecular weight of 339.39, papaverine is a white crystalline solid. It has a melting point of 147°C, a density of 1.337 g/ml, and is registered under CAS number 58-74-2. Light and moisture sensitive, it is soluble in alcohol, ether, acetone, and benzene, with limited solubility in chloroform, petroleum ether, and water (35 mg/L at 17°C). Its pH range is 2.0 to 2.8, with a pKa of 8.07, indicating a relatively weak acid.

Types of Papaverine

Papaverine hydrochloride (CAS Registration Number: 61-25-6) is a common form, a white crystal or powder with a molecular weight of 375.85, melting point of 220-225°C, soluble in alcohol and chloroform, and water solubility of 25mg/ml.

Other Information about Papaverine

1. Manufacturing Method of Papaverine

Papaverine is produced mainly through chemical synthesis, involving the Schotten-Baumann reaction for amide synthesis, followed by cyclization through the Bischler-Napieralski reaction, and mild dehydrogenation to synthesize papaverine.

2. Papaverine Side Effects

Reported side effects include constipation, dizziness, hot flashes, dry mouth, and palpitations. It is considered safe with no serious side effects but should be used cautiously by glaucoma patients due to potential increases in intraocular pressure.

3. Papaverine Legal Information

Papaverine is regulated under national dangerous goods shipping, storage regulations, and aviation law, classified as a poisonous substance.

4. Handling and Storage Precautions

Avoid contact with strong oxidizing agents. Use protective clothing, gloves, goggles, and a local exhaust system when handling. In case of fire, extinguish using appropriate means. Store in a tightly closed glass container away from light in a cool, well-ventilated area.

What Is Barbituric Acid?

Barbituric acid, a heterocyclic compound with a pyrimidine skeleton, is also known as malonyl uric acid. Discovered by Adolf von Beyer, it is a colorless, odorless solid synthesized by dehydrating malonic acid and urea under acidic conditions, with diethyl malonate currently used in its synthesis.

Physicochemical Properties of Barbituric Acid

1. Name:
English Name: Barbituric Acid
IUPAC Name: 1,3-diazinane-2,4,6-trione

2. Molecular Formula:
C4H4N2O3

3. Melting Point:
245°C (decomposes)

4. Solubility:
Slightly soluble in water and ethanol, insoluble in ether, soluble in hot water

Bioactivity of Barbituric Acid Derivatives (Barbiturates)

Barbiturates, derivatives of barbituric acid, have central nervous system depressant effects. Notable examples include barbital, phenobarbital, amobarbital, allobarbital, cyclobarbital, pentobarbital, thiopentanal, thiaminal, and hexobarbital. Barbituric acid itself, however, lacks CNS depressant effects.

Mechanism of Action of Barbiturates

Barbiturates bind to GABAA receptors, open chloride channels, and enhance inhibitory nerve function by depolarizing synaptic membranes.

Uses of Barbituric Acid Derivatives

Barbiturates were the primary sedatives and sleeping pills until the 1950s but have been largely replaced by benzodiazepine derivatives due to risks of dependence, withdrawal symptoms, and vitamin deficiencies. Currently, their use is limited to a few applications such as euthanasia and epilepsy treatment.

What Is Nonane?

Nonane is an organic compound with the chemical formula C₉H₂₀, featuring 35 isomers. Predominantly, the term nonane refers to its linear structure variant. This linear alkane, comprising nine carbon atoms, appears as a colorless, oily liquid at room temperature, emitting a sweet aroma. It is insoluble in water yet dissolves in ethanol.

Nonane is industrially derived from naphtha fractionation and can be synthesized in laboratories by heating nonanoic acid with hydrogen iodide and phosphorus. Its applications span the petroleum and chemical industries, notably in extracting and diluting paints, resins, fats, and waxes, and in formulating gasoline and diesel fuels.

With a flammable nature and a relatively low flash point of 31°C, precautions are necessary to mitigate risks associated with high temperatures and fire. Exposure to nonane may result in irritation upon inhalation, skin contact, and eye exposure, necessitating the use of appropriate protective gear and ventilation.

Uses of Nonane

Nonane finds extensive use in the petroleum and chemical industries, serving as a critical component in biodegradable detergents and as an effective organic solvent. Its solvent properties are exploited in extracting and diluting substances such as paints, resins, fats, and waxes. Nonane is also incorporated in gasoline and diesel fuels and is a constituent of kerosene—a heavy oil obtained through the fractional distillation of crude oil between 150°C and 270°C. Post-catalytic cracking and hydrogenation, kerosene is utilized in various fuel forms, including domestic kerosene and jet fuel.

Properties of Nonane

Nonane, a linear alkane with nine carbon atoms, is a colorless, oily liquid, characterized by a sweet petroleum odor. Its boiling point stands at 150.8°C, with a melting point of -53.6°C, and a specific gravity of 0.718g/cm³, indicating its lighter density relative to water. The compound’s low polarity renders it nearly insoluble in water, though it readily dissolves in nonpolar organic solvents. Nonane exhibits low reactivity towards polar reagents but may combust upon contact with strong oxidizing agents.

Structure of Nonane

Nonane is characterized by a non-polar, linear alkane structure consisting of nine carbon atoms. Its molecular formula, C₉H₂₀, underscores a simple, saturated hydrocarbon chain without structural isomers. This configuration imparts chemical stability and minimal reactivity towards strong acids and bases.

Other Information about Nonane

Manufacturing Method of Nonane

Nonane is produced from petroleum through various methods:

1. Oil Refining:
Directly obtained from the petroleum refining process, nonane is separated from crude oil mixtures by distillation, specifically from light oils like petroleum ether and naphtha, using fractional distillation.

2. Catalytic Decomposition:
This method involves breaking down large hydrocarbon molecules into smaller ones during oil refining, using acidic zeolite catalysts for thermal decomposition.

3. Alkylation:
Larger alkane molecules are produced by reacting isobutane with olefins in the presence of an acid catalyst, although this method is less commonly employed and primarily documented at the laboratory scale.

4. Fischer-Tropsch Method:
Nonane, among other alkanes, is synthesized by reacting synthesis gas in the presence of a catalyst, with subsequent fractional distillation employed to isolate nonane.