月: 2023年1月

What Is Acetanilide?

Acetanilide is an organic compound with chemical formula C8H9NO and specific formula C6H5NHCOCH3. Its IUPAC nomenclature is N-phenylacetamide, and other names include N-acetylaniline, N-acetylbenzeneamine, acetenyl, etc.

Its CAS number is 103-84-4. It has a molecular weight of 135.16, a melting point of 114-117°C, and a boiling point of 304-305°C. At room temperature, it is a white powder or plate-like crystal. It has a peculiar odor similar to that of esters. Its density is 1.219 g/cm3. It is soluble in diethyl ether, benzene, and toluene, and soluble in ethanol and acetone.

It is not soluble in water because the molecule is not highly polar, and its solubility in water is 5.2 g/kg (at 20°C). However, it is soluble in hot water.

Uses of Acetanilide

The main uses of acetanilide are as a synthetic raw material in the synthesis of various organic compounds such as dyes, pharmaceuticals, dyestuffs, and fibers.

It is also used as a stabilizer for hydrogen peroxide and as a rubber vulcanization accelerator. It is also used as an azo pigment in toners.

As a pharmaceutical raw material, it is especially used as a raw material for 4-acetamidobenzenesulfonyl azide, an intermediate in sulfa drugs. Acetanilide is also known for its antipyretic and analgesic properties as a member of the same family of drugs as acetaminophen. It was once marketed as a mass-market drug and was known as antifebrin.

In addition to ordinary organic synthesis, they are sometimes used in affinity capillary electrophoresis studies of drug-protein binding. It is sometimes used as a standard in elemental analysis, in which case a dedicated high-purity product is used.

However, it is not widely used today because many cases of methemoglobinemia causing liver and kidney damage and toxic effects such as blood cell destruction and convulsions have been observed. It has been replaced by less toxic compounds such as acetaminophen.

Properties of Acetanilide

Acetanilide is a stable compound in air, but reacts violently with strong oxidizers and strong bases. Therefore, acetanilide should be stored away from strong oxidizers and strong bases. Its flash point is 161°C, and it is believed to ignite when heated to 545°C.

Types of Acetanilide

Acetanilide is sold mainly as a reagent product for research and development. It is available in 1g, 5g, 100g, 500g, and 1kg volumes and can be handled at room temperature.

Other Information on Acetanilide

1. Synthesis of Acetanilide

Acetanilide is synthesized by acetylation of aniline. The main acetylating agent is acetic anhydride, but anilinium salts and acetyl chloride can also be used.

The synthesis of acetanilide with aniline and acetic anhydride is a very typical reaction for the formation of amides and is therefore often discussed on the study.

2. Typical Chemical Reaction of Acetanilide

Nitration of acetanilide yields nitroacetanilide. This reaction is an ortho- and para-oriented aromatic nucleophilic substitution reaction, yielding 2-nitroacetanilide and 4-nitroacetanilide. Of these, 4-nitroacetanilide is particularly used as a raw material for dyes.

Note that 2-nitroacetanilide and 4-nitroacetanilide can be treated with acid to remove the acetyl group, giving 2-nitroaniline and 4-nitroaniline, respectively.

Reports also suggest that when acetanilide is used as a drug, acetaminophen is produced in the body as a metabolite of acetanilide.

What Is Acetylene Gas?

Acetylene gas is a 2-carbon hydrocarbon.

It has the simplest structure of all the alkynes, with the molecular formula C2H2 and the IUPAC systematic name “ethyne”. At room temperature, it is a colorless, odorless gas with a gas density of 0.908, slightly lighter than air.

It is not a naturally occurring substance but is obtained through the thermal decomposition of hydrocarbons such as natural gas and naphtha.

Uses of Acetylene Gas

Acetylene gas is used as a flammable gas in metal welding and fusing processes. Its high flame temperature enables efficient work, and its low oxygen consumption reduces the number of oxygen containers used. It is used for pressure welding of reinforcing bars, thermal spraying, brazing, cutting of steel plates, and quenching of steel materials.

When completely combusted, the flame temperature of acetylene reaches 3,300°C, higher than other combustible gases like methane (2,780℃), propane (2,800℃), propylene (2,900℃), and ethylene (3,000℃).

It is also easy to handle due to its low ignition temperature of 305°C. Furthermore, its oxygen consumption is about one-fourth that of propane gas. Acetylene is used in synthesizing organic compounds such as ethylene, acetaldehyde, and benzene.

The following are applications for higher-purity acetylene gas:

• Raw material for semiconductor carbon
• Raw material for the production of hard carbon films
• Raw material for the synthesis of new materials such as carbon nanotubes and carbon nano coils
• Atomic absorption spectrometry

Principle of Acetylene Gas

This section explains the principle of acetylene gas in terms of its properties, synthesis methods, and chemical reactions.

1. Properties of Acetylene Gas

Acetylene gas, represented by the chemical formula C2H2, has one triple bond in the molecule and is linear. At room temperature, it is soluble in water and more soluble in organic solvents like tetrahydrofuran.

While useful as a flammable gas, it is extremely easy to ignite and burns explosively in the absence of oxygen, so care must be taken when handling it.

2. Acetylene Gas Production Methods

The main methods for producing acetylene gas include:

• Carbide method: Adding water to calcium carbide.
• Pyrolysis method: Thermal decomposition of hydrocarbons.

Small-scale applications use the carbide method, while the pyrolysis method is for large-scale industrial manufacturing.

3. Chemical Reaction of Acetylene Gas

Addition Reactions: The triple bond of acetylene is susceptible to addition reactions, producing ethylene and ethane with hydrogen addition. It also reacts with hydrogen halides.

Addition Polymerization: Acetylene can undergo addition polymerization, producing monovinylacetylene, a raw material for butadiene, and chloroprene for synthetic rubber. Benzene is synthesized from three acetylene molecules. Polyacetylene is used as a conductive material.

Types of Acetylene Gas

Acetylene gas is filled into gas cylinders as dissolved acetylene, pressurized, and dissolved in a solvent like acetone or DMF.

Dissolved acetylene generally has a slight odor due to impurities like phosphine and hydrogen sulfide. It is mainly used for metal welding and fusion processing.

Other high-purity products are used as raw materials for semiconductor carbon and for the production of hard carbon films. Compressed acetylene gas should be handled with caution due to its explosive nature.

What Is Adipic Acid?

Adipic acid is an important dicarboxylic acid in the industry, also known as hexanedioic acid or 1,4-butanedicarboxylic acid. It’s a white, odorless, crystalline powder with the chemical formula (CH2)4(COOH)2. Initially prepared from fats, its name originates from the Latin words ‘adeps’ and ‘adipis’, meaning ‘animal fat’.

Properties of Adipic Acid

Adipic acid is soluble in ethanol, hot water, and acetone, but slightly soluble in water. Its acidic aqueous solutions exhibit a two-step proton dissociation with pKa values of 4.4 and 5.4. Upon heating with barium hydroxide, it undergoes ketonization to form cyclopentanone.

Adipic Acid Manufacturing Process

Commercially, adipic acid is produced by oxidizing cyclohexane. The process begins with the formation of a mixture of cyclohexanone and cyclohexanol, oxidized with nitric acid. This multi-step pathway also produces by-products like glutaric acid and succinic acid. Alternative methods to avoid nitrous oxide emissions include hydrocarboxylation of butadiene and oxidative cleavage of cyclohexene with hydrogen peroxide.

Uses of Adipic Acid

Adipic acid is primarily used as a raw material in polymers like Nylon 66 and polyester resin. It’s also a key ingredient in alkyd resins, pharmaceuticals, food additives, and as a standard substance in acid-base reactions. Its diesters serve as plasticizers and synthetic lubricants.

Safety of Adipic Acid

While mildly toxic and a skin irritant, adipic acid’s major environmental concern is the nitrous oxide emitted during its production. This gas contributes significantly to ozone depletion and has a high greenhouse effect. Manufacturers have introduced processes to convert this gas into nitrogen and oxygen to mitigate environmental impact.

What Is Sodium Azide?

Sodium azide is a white crystalline powder at room temperature with the molecular formula NaN3. It has a molecular weight of 65.01, a specific gravity of 1.85, a boiling point of about 300°C, and a melting point of 275°C. This compound is soluble in water and liquid ammonia but insoluble in ethanol and ether. It is potentially explosive when in contact with metals and is toxic, necessitating careful handling.

Properties of Sodium Azide

Sodium azide is well known for its toxicity and the risk of explosion. Inhalation or ingestion can cause serious health issues such as dizziness, breathing difficulties, and convulsions. Proper precautions must be taken to avoid fire, explosion, and exposure.

Uses of Sodium Azide

• Introduction of Azide Groups: Sodium azide is used to introduce azide groups into organic compounds, enabling cycloaddition reactions with alkynes in the presence of copper catalysts.
• Introduction of Amino Groups: The azide group can be converted to an amino group, for example, through palladium-catalyzed catalytic hydrogen reduction. Sodium azide was previously used in automobile airbags but is now being replaced due to toxicity concerns.
• Preservatives: It’s used as a preservative in commercial antibodies but is not included in antibodies labeled for horseradish peroxidase due to enzyme inhibition.
• Dissolved Oxygen (DO) Measurement: Used in the Winkler method for measuring DO in water, preventing inaccurate measurements due to nitrite ions.

Reactivity of Sodium Azide

Sodium azide decomposes into sodium and nitrogen at high temperatures and reacts with acids to produce hydrogen azide (HN3), which is both toxic and explosive.

Production of Sodium Azide

Industrially, sodium azide is produced through the Wislicenus process, involving the reaction of liquid ammonia with nitrous oxide (N2O) via sodium amide (NaNH2).

What Is Acrolein?

Acrolein, known as 2-propenal in IUPAC nomenclature, is an unsaturated aldehyde with a carbon-carbon double bond. It is a colorless or slightly yellowish liquid at room temperature with a strong pungent odor. It has a molecular weight of 56.06, a melting point of -88°C, and a boiling point of 53°C. This compound is produced during the thermal decomposition of fats and oils and is known for its toxicity and pungent odor.

Uses of Acrolein

Acrolein is used as a synthetic raw material for glycerin and allyl alcohol, and in the synthesis of pharmaceuticals such as methionine. It has applications in fiber treatment agents, cross-linking binders, and the production of colloidal osmium, rhodium, and ruthenium. It was historically used in resin components for paints but is less common now due to the prevalence of silicone resin paints. In medical research, acrolein is studied as a potential biomarker for cerebral infarction.

Principle of Acrolein

1. Properties of Acrolein

Acrolein is the simplest unsaturated chain aldehyde, highly reactive and prone to polymerization, especially in the presence of light, alkalis, and strong acids. Stabilizers like hydroquinone are often used to prevent oxidation and polymerization.

2. Synthesis of Acrolein

In laboratory synthesis, acrolein is produced by dehydrating glycerin with dehydrating agents like potassium hydrogen sulfate.

3. Chemical Reaction of Acrolein

Acrolein undergoes 1,4-nucleophile addition and participates in Michael addition reactions. It can be reduced to propanol via propionaldehyde.

Types of Acrolein

As an unstable compound, acrolein is not widely manufactured or sold. Available forms include aqueous solutions and methanol-water solutions at various concentrations, typically stored refrigerated or frozen.

What Is Acrylonitrile?

Acrylonitrile (AN), also known as vinyl cyanide, is a clear, colorless liquid with a sweet odor, which may turn pale yellow in light. It’s soluble in organic solvents like ethanol and acetone. With the molecular formula CH2=CHCN and a molecular weight of 53.06, acrylonitrile has a melting point of -83 to -84°C and a boiling point of 78°C. It’s an important chemical intermediate but is toxic and flammable (flash point -1°C), requiring careful handling and storage to prevent polymerization.

Uses of Acrylonitrile

Acrylonitrile is used in polymerization to form various products. Polyacrylonitrile (PAN), a polymer of acrylonitrile, is a key component in fibers for knitwear like sweaters and socks. It’s also a raw material for synthetic resins (such as ABS and AS resins) and synthetic rubber used in tires, packing, and conveyor belts.

Acrylonitrile Reaction

Acrylonitrile primarily reacts as a monomer to produce polymers. Its structure allows it to undergo Michael addition, making it a useful cyanoethylation agent. It also dimerizes to form adiponitrile, a raw material for nylon production.

Production of Acrylonitrile

Industrially, acrylonitrile is produced via the SOHIO Process, where propylene reacts with ammonia and oxygen in the presence of a metal oxide catalyst. Byproducts like acetonitrile and hydrogen cyanide are also utilized in various industrial applications.

What Is Methyl Acrylate?

Methyl acrylate, an organic acrylic ester also known as methyl propenoate, is a clear, colorless liquid with a fruity ester odor. It’s volatile, flammable, and designated as a hazardous material, with molecular formula CH2=CHCOOCH3 and CAS No. 140-88-5.

Uses of Methyl Acrylate

Widely used in industrial applications, methyl acrylate is a reactant in various chemical reactions and serves as a raw material for acrylic fibers, resins, adhesives, paints, emulsions, coatings, and copolymerization processes. It’s utilized in automotive parts, leather processing, acrylic rubber manufacturing, and as an adhesive in LCD panels and smartphones.

Principle of Methyl Acrylate

Methyl acrylate has a molecular weight of 86.1, melting point of -76.5℃, boiling point of 80.3℃, flash point of -2.8℃, and is water-soluble. Its reactivity is enhanced by the olefin moiety, and it’s prone to self-polymerization, often stabilized with hydroquinone monomethyl ether. It can include impurities like methyl acetate and methyl propionate.

1. Method of Synthesis of Methyl Acrylate

Synthesized from acrylic acid esters, methyl acrylate is highly reactive and stabilized for safety.

Types of Methyl Acrylate

Available in both small volumes for reagent use and larger capacities for industrial applications, with packaging ranging from small bottles to large drums and lorries.

Other Information on Methyl Acrylate

Safety Information on Methyl Acrylate

Methyl acrylate poses risks like skin burns, eye damage, inhalation toxicity, possible carcinogenesis, and aquatic toxicity. Protective gear is essential, and it’s regulated under various safety standards, including OSHA guidelines for hazardous and flammable materials.

What Is Acrylic Acid?

Acrylic acid is an unsaturated carboxylic acid, primarily obtained through propylene oxidation. It’s a clear, colorless liquid with a distinct odor, used in making water-absorbent polyacrylic acid and acrylic fiber.

Additionally, it’s utilized in producing dispersants and thickening agents, with its physical properties adjustable by altering the carbon count in its alkyl moiety. As a flammable liquid, it requires controlled polymerization inhibitors and oxygen levels due to potential runaway reactions. Handling acrylic acid necessitates protective gear due to its skin-irritating nature.

Acrylic Acid Manufacturing Process and Uses

Acrylic acid production involves oxidizing propylene to acrolein, then further to acrylic acid. Its applications include making superabsorbent polymers (SAPs) for disposable diapers and raw materials like methyl acrylate and butyl acrylate for acrylic fibers. It’s also a precursor for synthetic resins, dispersants, flocculants, and thickening agents.

Polymers Using Acrylic Acid as a Raw Material

Polymers derived from acrylic acid include polyacrylic acid, sodium polyacrylate, and cross-linked copolymers, widely used in superabsorbent polymers. Varying the copolymerized monomers with acrylic acid, like alkyl methacrylate, results in different polymers employed as thickeners in cosmetics and other products.

Acrylic Acid Safety and Regulations

Acrylic acid, a flammable liquid with a pungent odor, can undergo polymerization reactions. Safe handling involves controlling oxygen concentration and adding polymerization inhibitors. It’s classified as a deleterious substance, skin corrosive, and irritant, thus subject to risk assessment and careful management.

What Is an Analyzer

An analyzer is classified into different categories according to the field in which they are used: laboratory analyzer for experiments and research, environmental analyzer, analyzer for work environment and security, analyzer for physical examination (medical analyzer), and analyzer for bio-related applications (eg, DNA analysis).

Exhibitions (analyzer exhibitions) are held in various regions according to the use and type of analyzer.

Uses of Analyzers

For example, they are used in research institutes such as universities, private companies such as material and pharmaceutical manufacturers, and also in the Forensic Science Laboratory of police departments.

For example, liquid chromatography and gas chromatography are used to determine the composition and amount of impurities in a substance. An urban-visible spectrophotometer is used to determine the concentration of components in a liquid, and an infrared spectrophotometer is used to determine the chemical structure of a substance.

There are also nitrogen oxide analyzers (Nox analyzers), ozone analyzers for environmental analysis, and TOC analyzers for water pollution analysis.

Principle of Analyzers

The principles of analyzers vary greatly depending on the model. In this article, we will introduce the principles of high-performance liquid chromatography (HPLC), which is one of the most frequently used analyzers. HPLC is a device that injects a liquid to be analyzed into a column to separate each component.

The column is packed with a stationary phase, and the retention time of each component varies depending on its interaction with the stationary phase and adsorption power. Since the retention time differs, the time required for elution differs for each component, that is, the components can be separated and detected as separate peaks.

The devices that make up liquid chromatography include a liquid (mobile phase) to flow the sample into the column, a pump to flow the mobile phase, an autosampler to inject the sample (or an injector to inject manually), an oven to maintain a constant column temperature and a detector. The sample, injected into the column at a constant flow rate by the pump, passes through the stationary phase in the column, is separated into individual components, and these separated components are then detected by the detector. Each component can be determined from the area value and size ratio of the detected peaks.

What Is a Spur Gear?

A spur gear is a type of gear with a cylindrical tooth trace that is straight and parallel to the shaft. A spur gear can be used for a wide range of applications, from light to heavy loads and from low to high speeds, depending on the design. Because they are relatively easy to machine, spur gears are the most commonly used of all types of gears.

Spur gears have many options in terms of material (metal or resin), processing method (machining, molding, or sintering), and lubrication (type and availability of lubricant). Therefore, they must be selected appropriately for each application.

Uses of Spur Gears

Spur gears are versatile and are one of the most widely used machine elements. They are used in a wide range of fields due to their large drive transmission force, freely selectable speed of rotation, and the convenience of being able to change the direction of rotation and having a large drive transmission force.

Spur gears are used in a wide variety of applications, including drive transmission parts for toy cars, drive transmission parts inside clocks and watches, drive transmission parts for various printers, drive transmission parts for industrial robots, and drive transmission applications for power tools and agricultural machinery.

Principle of Spur Gears

Spur gears transmit motion to other parts of a gear by meshing the teeth one after another. Because the teeth of spur gears are cut parallel to the direction of the shaft, theoretically no axial force (thrust load) is generated, which leads to a reduction in equipment size and simplification of the overall structure.

With a pair of meshing spur gears, the direction of rotation is opposite, the number of rotations is inversely proportional to the number of teeth, and the torque is also proportional to the number of teeth. These drive transmission theories do not depend on tooth size, so it is possible to think in the same way from small power to large power.

When spur gears are used for large power portions, it is common to use metal as the material and lubricate the meshing area. Without lubricant, the gears will wear out in an extremely short time. Its hardness can be increased by hardening the surface of the metal material, thereby extending the life of the gears.

When spur gears are used for medium to low-load areas, the resin can be used as a material. In addition, in the case of resin, it is easier to obtain cost benefits by molding and manufacturing gears.