月: 2023年1月

What Is Hexamethylenetetramine?

Hexamethylenetetramine, a heterocyclic aliphatic amine, boasts the chemical formula C₆H₁₂N₄. Commonly known as hexamine, urotropine, methenamine, and 1,3,5,7-tetraazaadamantane, this compound serves various industrial and medical purposes.

It is classified under several regulations: as a Class D substance, a “Class I designated chemical substance, and as an undesignated additive.

Uses of Hexamethylenetetramine

Hexamethylenetetramine finds its use in therapeutic settings, particularly for treating cystitis and urinary tract infections. It transforms into formaldehyde in the urine, which then exhibits antiseptic properties. While used as an antiseptic preservative in food products internationally, it is not utilized as a food preservative in Japan.

Properties of Hexamethylenetetramine

This compound appears as a colorless, odorless crystal or crystalline powder that sublimates at 280°C and ignites at 410°C. It is soluble in water, ethanol, and chloroform, but insoluble in benzene, acetone, and ether.

Structure of Hexamethylenetetramine

Hexamethylenetetramine’s structure is a tetrahedral cage, similar to adamantane, with nitrogen atoms at the four vertices connected by methylene links. It features a molar mass of 140.186 g/mol and a density of 1.33 g/cm³ at 20°C.

Other Information on Hexamethylenetetramine

1. Synthetic Method

Discovered by Alexander Butlerov in 1859, hexamethylenetetramine is produced industrially via the reaction of formaldehyde and ammonia.

2. Reactions Involving Hexamethylenetetramine

It is instrumental in organic synthesis, notably in the Duff reaction for formylating aromatic rings, the Sommelet reaction for synthesizing aldehydes from benzyl halides, and the Delépine reaction for creating amines from alkyl halides.

3. Hexamethylenetetramine as a Base

Acting as an amine-like base, it undergoes protonation and N-alkylation. For instance, N-alkylation with 1,3-dichloropropene yields Quaternium-15, a quaternary ammonium salt consisting of cis and trans isomers.

What Is Hexamethylenediamine?

Hexamethylenediamine, an aliphatic amine with two amino groups (-NH₂), is an important compound in the chemical industry. Also known as hexane-1,6-diamine, 1,6-hexadiamine, and 1,6-diaminohexane, it exhibits basic properties influenced by its structure and substituents.

Uses of Hexamethylenediamine

Primarily, it serves as a key ingredient in the manufacture of nylon 66 and hexamethylene diisocyanate for polyurethane production, showcasing its versatility in creating both industrial products and household goods.

1. Nylon 66

Nylon 66, derived through condensation polymerization of adipic acid and hexamethylenediamine, is known for its heat resistance, tensile strength, and chemical resistance. It’s used in automotive components, textiles, and various coatings.

2. Polyurethane

Polyurethane, featuring high tensile strength and elasticity, finds applications in apparel, soundproofing materials, adhesives, and automotive parts, benefiting from its elastic properties.

Properties of Hexamethylenediamine

With the formula H2N(CH2)6NH2 and a molecular weight of 116.20, hexamethylenediamine is a solid at room temperature, soluble in water, and displays strong basicity. It reacts with acids and certain metals and can absorb CO₂ from the air, forming carbonates.

Production and Legal Aspects of Hexamethylenediamine

1. Production Methods

Produced via the ADA method, electrolytic reduction dimerization of acrylonitrile, and hydrocyanation of butadiene, hexamethylenediamine’s production has evolved to optimize cost and efficiency. Alternative methods include the diol, caprolactam, and propylene-allyl chloride processes.

2. Legal Status

Regulated under various laws due to its flammable and deleterious properties, hexamethylenediamine requires careful handling and storage to prevent environmental and health risks.

3. Handling and Storage Precautions

Special precautions include avoiding storage with acidic substances, using moisture-protective packaging, and careful handling to prevent metal corrosion. Storage in non-iron containers is recommended to mitigate moisture absorption and corrosive effects.

What Is Propylene Gas?

Propylene, a colorless gas with a faintly aromatic odor, has the chemical formula C₃H₆ and a molecular weight of 42.08. Known also as propene, methylethylene, or methylethene, it is a flammable, unsaturated hydrocarbon. Its high reactivity allows for polymerization and oxidation, making it crucial in the synthetic chemical industry.

Properties of Propylene Gas

1. Physical Properties

With a melting point of -185.2°C and a boiling point of -47.6°C, propylene dissolves in ether and ethanol but is nearly insoluble in water. It is usually stored as a liquid under pressure or as a gas in approved containers at room temperature.

2. Environmental and Health Effects

Produced by combustion and present in some heating gases, propylene has low acute toxicity and is not considered carcinogenic. However, as a volatile organic compound (VOC), its emissions are regulated.

Uses of Propylene Gas

1. Basic Raw Materials

Essential for producing polypropylene, acrylonitrile, phenol, solvents, synthetic detergents, and as a component of liquefied petroleum gas, propylene is pivotal in manufacturing a broad range of petrochemical products, including isopropyl alcohol and acetone.

2. Applications

Polypropylene, derived from propylene polymerization, finds uses in automobile bumpers and packaging films. Propylene is also an alternative fuel for metalworking processes such as welding and brazing.

Production and Reactions of Propylene Gas

1. Manufacturing Process

Produced by fractional distillation from cracked petroleum gas, steam cracking, and dehydrogenation of propane, propylene can also result from the olefin metathesis reaction of ethylene and 2-butene using specific catalysts.

2. Chemical Reactions

Used in coordination polymerization to synthesize polypropylene and other alkenes, propylene undergoes various chemical reactions, including oxidation and halogenation, ultimately burning to form water and carbon dioxide.

3. Legal Status and Handling

While not designated under certain toxic substance control laws, propylene is regulated as a hazardous, flammable gas, requiring specific storage and handling precautions to avoid risks such as ignition and explosion.

4. Storage and Handling Precautions

Storage in high-pressure containers, avoidance of ignition sources, proper valve management, explosion-proof ventilation, and personal protective equipment are among the precautions for safely handling propylene.

What Is Propyl Alcohol?

Propyl alcohol refers to aliphatic alcohols with the molecular formula C₃H₈O, including two isomers: n-propyl alcohol (1-propanol) and isopropyl alcohol (2-propanol).

n-propyl alcohol, or 1-propanol, is a primary alcohol with its hydroxyl group on the terminal carbon (CH₃CH₂CH₂OH). Isopropyl alcohol, or 2-propanol, is a secondary alcohol with the hydroxyl group on the middle carbon (CH₃CH(OH)CH₃).

Uses of Propyl Alcohol

n-propyl alcohol serves as an industrial solvent in applications such as printing inks, textiles, cosmetics, window cleaners, polishing agents, and antiseptics. Isopropyl alcohol is utilized in the synthesis of acetone, disinfectants, solvents for eyeglasses and electronic devices, and as a fuel tank drying agent.

Properties of Propyl Alcohol

1. N-Propyl Alcohol

A colorless liquid with an ethanol-like aroma, n-propyl alcohol has a melting point of -126.5°C, a boiling point of 97.2°C, and is flammable with a flash point of 24°C. It is soluble in water, ethanol, and diethyl ether and requires careful handling due to its classification under hazardous substance regulations.

2. Isopropyl Alcohol

Isopropyl alcohol, a volatile, flammable liquid, has a melting point of -89.5°C, a boiling point of 82.4°C, and a flash point of 11.7°C. It reacts with oxidizers to form methyl ketone and is subject to similar safety regulations as n-propyl alcohol.

Production Methods of Propyl Alcohol

1. N-Propyl Alcohol

n-propyl alcohol is industrially obtained by hydrogenating propionaldehyde, derived from ethylene hydroformylation, using a rhodium complex catalyst.

　　C₂H₄+CO+H₂ → CH₃CH₂CHO
　　CH₃CH₂CHO+H₂ → CH₃CH₂CH₂OH

2. Isopropyl Alcohol

Isopropyl alcohol is produced from propylene via direct or indirect hydration. The direct method involves reacting water vapor with propylene at high temperature and pressure, while the indirect method involves sulfation followed by hydrolysis.

• Direct Hydration Method: CH₃CH=CH₂+H₂O → CH₃CH(OH)CH₃
• Indirect Hydration Method: CH₃CH=CH₂+H₂SO₄ → CH₃CH(OSO₃H)CH₃
  CH₃CH(OSO₃H)CH₃+H₂O → CH₃CH(OH)CH₃+H₂SO₄

What Is Propionic Acid?

Propionic acid, a 3-carbon saturated fatty acid, is a clear, colorless liquid with a characteristic odor.

Also known as propanoic acid, it dissolves readily in water, ethanol, and acetone. Propionic acid is produced through the hydrolysis of propionitrile or the oxidation of 1-propanol.

It is designated as a Class 4 hazardous substance due to its toxic properties, including mucous membrane irritation and corrosiveness. Naturally occurring as a microorganism metabolite, propionic acid is present in fermented foods like miso, soy sauce, and cheese.

Uses of Propionic Acid

As a carboxylic acid, propionic acid (CH3CH2COOH) finds wide industrial use in pharmaceuticals, herbicides, fragrances, and resins, and serves as a preservative by inhibiting mold and bacterial growth.

1. Use in Organic Synthesis

Valued as a solvent, dissolution aid, and esterifier, propionic acid contributes to the production of polymers, plastics, and non-steroidal anti-inflammatory drugs (NSAIDs).

2. Use in Flavoring

Propionic acid’s unique odor lends itself to fruit flavorings, such as ethyl propionate, which imparts a pineapple-like aroma and is utilized in food flavoring.

3. Antimicrobial Activity and Fungicide Use

Known for its antimicrobial properties, particularly in cheese, propionic acid is employed as a food additive to prevent mold growth in cheese, bread, and confectionery, and as a pH adjuster, shampoo additive, and livestock feed additive.

Properties of Propionic Acid

Propionic acid has a molecular formula of C3H6O2, a molecular weight of 74.08 g/mol, melting point of -20.83°C, and is highly soluble in water, ethanol, chloroform, and ether.

Structure of Propionic Acid

Propionic acid, with its linear carboxylic acid structure, is soluble in water and exhibits low reactivity towards oxidation, reduction, and thermal decomposition. It is flammable when mixed with strong oxidizers and its vapor can be irritating.

Other Information on Propionic Acid

Production Methods

Primarily synthesized chemically, propionic acid is often a byproduct of other compounds’ synthesis, notably acetic acid production from naphtha oxidation. Direct synthesis from n-propanol, propionaldehyde, or hydrolysis of propiononitrile is less common. Fermentation using propionibacterium freudenreichii, or propionic acid bacteria, represents an alternative method.