月: 2023年1月

What Is Guanine?

Guanine is a white powder heterocyclic compound. Its IUPAC name is 2-amino-1,9-dihydro-6H-purin-6-one, and it is also known as 2-aminohypoxanthine or 2-amino-6-hydroxypurine.

Its chemical formula is C5H5N5O, molecular weight is 151.13, and its CAS number is 73-40-5.

Uses of Guanine

Guanine was discovered in 1844 in bird excrement. The name comes from the Spanish word guano, meaning bird or bat droppings.

It is also a major component of the silvery-white parts of fish such as salmonids, hake, and Pacific saury.

1. Nucleobase of Nucleic Acids

Guanine is one of the major bases that make up nucleic acids, forming base pairs with cytosine via three hydrogen bonds in the double helix structure of DNA.

The carbonyl group oxygen at position 6 of Guanine acts as a hydrogen bond acceptor, while the hydrogen bond to the nitrogen atom at position 1 and the hydrogen on the primary amine at position 2 act as hydrogen bond donors.

Guanine quadruplex (G4), which is a higher-order structure of guanine in DNA, has been attracting attention since around 2015, and compounds that stabilize Guanine quadruplex (G4 ligands) have been suggested to inhibit cancer, and research is being conducted to explore their application in anticancer drugs and other drugs.

2. Cosmetics

Crystalline Guanine has been used as an additive in various products such as shampoos, eye shadows, and nail polishes because it reflects light in rainbow colors like pearls when applied.

It is also used in metallic paints and imitation pearls. Guanine crystals are rhombic plate-like crystals composed of multiple transparent layers. Because of its high refractive index, each layer partially reflects and transmits light, producing a pearly luster.

Properties of Guanine

Guanine decomposes at 360 °C and is solid at room temperature. It is insoluble in water and organic solvents, but is well soluble in dilute acids.

The acid dissociation constant (pKa) is 3.3 for the amide moiety, 9.2 for the secondary amine moiety, and 12.3 for the primary amine moiety.

The acid dissociation constant is a quantitative measure of the strength of an acid; the smaller the pKa, the stronger the acid.

Other Information on Guanine

1. Production Method of Guanine

Guanine and uracil are obtained by the Fischer-Tropsch method by heating an equimolar mixture of CO, H2, and NH3 at 700°C for 15 to 24 minutes, followed by quenching and heating again at 100 to 200°C for 16 to 44 hours under alumina catalyst.

It can also be obtained by heating the amine-substituted pyrimidine 2,4,5-triamino-1,6-dihydro-6-oxypyrimidine  in formic acid for several hours, according to Traube’s purine synthesis.

2. Precautions for Handling and Storage

Handling
Avoid contact with strong oxidizing agents. It is important to use the product in a draft chamber with local exhaust ventilation. Wear personal protective equipment when using.

In case of fire
Guanine is nonflammable and will itself not burn. However, thermal decomposition may produce irritating gases and vapors such as carbon monoxide, carbon dioxide, and nitrogen oxides. Water spray, foam, powder fire extinguishers, carbon dioxide, dry sand, etc. should be used to extinguish the fire.

If adhered to skin
Care should be taken to prevent adhesion to skin. Always wear protective clothing such as a white coat or work clothes and protective gloves when using the product. It is important to never roll up the sleeves of protective clothing to avoid skin exposure.

In the unlikely event of skin contact, wash off with soap and copious amounts of water. If on clothing, remove all contaminated clothing and isolate. If symptoms persist, it is safer to seek medical attention.

In case of eye contact
Strongly irritating to eyes. Always wear protective eyewear or goggles when using this product as it can cause serious injury.

In the unlikely event of eye contact, rinse cautiously with water for several minutes. If wearing contacts, remove them if they can be easily removed and rinse thoroughly. Immediate medical attention is required.

Storage
Store in a tightly closed, light-shielded glass container. It is important to store in a cool, well-ventilated place, away from direct sunlight.

What Is Guanidine?

Guanidine is an organic compound with the molecular formula CH5N3. It is also known as imido carbonic acid diamide, and its CAS number is 113-00-8.

It has a molecular weight of 59.07, a melting point of 50°C, a boiling point of 160°C (decomposition), and exists as a colorless crystalline powder at room temperature. It is strongly basic, with an acid dissociation constant pKa of 12.5. It is readily soluble in water and also soluble in ethanol, methanol, and dimethylformamide.

It is a chemical found in nature in mushrooms and earthworms, and is also detected in human urine because it is produced by protein metabolism.

In air, it absorbs carbon dioxide, which changes its properties, so it must be stored in a tightly sealed container.

Uses of Guanidine

Guanidine is used as a raw material for plastics and explosives.

In addition, due to its ability to easily form hydrogen bonds, salts of guanidine are used in a variety of fields. For example, the hydrochloride salt (guanidinium chloride) and the thiocyanate salt (guanidine thiocyanate) are often used as protein denaturants in the biochemical field.

Synthetically, guanidine nitrate is used as an ingredient in gunpowder, and guanidine hydrochloride is used as a synthetic ingredient in pharmaceuticals and dyes.

Guanidine phosphate is used as an excellent fire retardant for paper and wood. In addition to being highly flame retardant, guanidine phosphate is believed to prevent moisture absorption and iron corrosion.

In recent years, research has been conducted to use guanidine as an alternative to fossil fuels. Guanidine and the guanidino group are strong bases, and there are many derivatives of guanidine that are used as strong bases in organic synthesis.

Other applications include raw materials for synthesizing photographic materials, disinfectants, and many other fields.

Properties of Guanidine

1. Chemical Properties of Guanidine

Guanidine is stabilized by delocalization of the positive charge of the conjugated acid on the three nitrogens due to resonance, and exhibits strong basicity. Thus, under physiological conditions, it exists as a protonated +1-valent cation (guanidinium ion).

When heated to 160°C, it releases ammonia and converts to melamine (C3H6N6).

2. Derivatives of Guanidine

A compound containing guanidino groups is arginine, a type of amino acid. Arginine is a substance known to play an important role in proteins, such as binding to DNA.

Among natural product alkaloids, compounds containing guanidino groups biosynthesized from arginine are known, and many of them have strong physiological effects, such as saxitoxin and tetrodotoxin.

In addition, nitroguanidine, in which a nitro group is substituted for guanidine, is a substance known as a raw material for explosives.

Types of Guanidine

Guanidine pure substances are sold primarily as reagent products for research and development; they are sold in volumes of 5 g, 10 g, etc., and are compounds that are sometimes stored under refrigeration due to their tidal properties.

Guanidine is more commonly sold as a salt than as guanidine itself. It is available as a reagent product for research and development and as an industrial chemical.

Available reagent products for research and development include guanidine hydrochloride, guanidine nitrate, guanidine thiocyanate, guanidine phosphate, guanidine carbonate, guanidine sulfamate, and guanidine hydrobromide.

Compounds with biochemical applications, such as hydrochloride and thiocyanate, are often available in grades such as molecular biology/biochemistry, so it is necessary to select the product grade that best suits your application. Types of capacities commonly exist, such as 25g, 100g, 500g, etc.

Similarly, guanidine hydrochloride, guanidine nitrate, guanidine phosphate, guanidine carbonate, guanidine sulfamate, and others are available as industrial chemicals.

Products such as 60% aqueous hydrochloride solutions may also be available. These products are used as raw materials for organic synthesis, raw materials for fiber treatment agents, raw materials for bioprocessing, and raw materials for clinical laboratories.

What Is Barium Chromate?

Barium Chromate, a chemical compound with formula BaCrO4 and CAS No. 10294-40-3, is a yellowish powdery solid used extensively in various industrial applications. It’s known for its limited solubility in water and strong reactivity with acids.

Uses of Barium Chromate

It’s employed as a pigment, a corrosion inhibitor, and in fireworks. In chemical processes, it’s used for spectrophotometric analysis and as an oxidizing agent.

Properties of Barium Chromate

1. Synthesis

Synthesized via precipitation reactions, it exhibits unique properties like green flame reactions and is generally stable under standard storage conditions.

2. Safety Concerns

As a hazardous hexavalent chromium compound, it poses significant health risks, including carcinogenicity and respiratory issues.

3. Legal and Regulatory Aspects

Strictly regulated, its usage is confined to specific applications under controlled conditions.

Types of Barium Chromate

Marketed mainly for specialized uses, it’s available in various quantities and requires careful storage and handling.

What Is Sodium Chromate?

Sodium Chromate, an inorganic compound with the formula Na2CrO4, is known for its CAS No. 7775-11-3. A yellow crystalline solid, it exhibits hygroscopic properties and forms multiple hydrates. Highly soluble in water, it’s used in various industrial applications.

Uses of Sodium Chromate

Applications range from the manufacture of paints and inks to wood preservatives in the petroleum industry. In medicine, it assists in red blood cell volume measurement. Its strong oxidizing power also makes it valuable in synthesizing chromium compounds.

Properties of Sodium Chromate

1. Synthesis

Synthesized from potassium dichromate and sodium hydroxide, or via a reaction involving chromium(III) oxide and sodium carbonate in oxygen presence.

2. Chemical Properties

Characterized by its reaction in acidic solutions and its transformation into various chromate ions. Nonflammable, it doesn’t burn by itself.

3. Regulatory Information

As a hexavalent chromium compound, it’s subject to stringent environmental and health regulations.

Types of Sodium Chromate

Marketed mainly for research, and available in various capacities, it requires careful handling due to its toxic nature.

What Is Potassium Chromate?

Potassium Chromate, an inorganic compound with the formula K2CrO4, has a CAS number of 7789-00-6. It’s characterized by its high solubility in water, insolubility in ethanol, and notable oxidizing and corrosive properties. Exposure risks include potential carcinogenic effects.

Uses of Potassium Chromate

Used as an oxidizer, Potassium Chromate is also a valuable analytical reagent, a mordant in textile dyeing, and a raw material for various chromates. Its applications extend to leather finishing, improving the material’s heat resistance, dyeability, and insulation.

Properties of Potassium Chromate

1. Synthesis of Potassium Chromate

Produced from Potassium Dichromate and Potassium Carbonate, or through the reaction of Potassium Hydroxide with Chromium Trioxide, its synthesis involves specific aqueous solutions and cooling processes.

2. Chemical Properties

With a crystal structure similar to Potassium Sulfate, Potassium Chromate exhibits basicity in aqueous solutions and forms various compounds with metals like silver and barium.

3. Regulatory Information

As a toxic hexavalent chromium compound, Potassium Chromate is subject to strict regulations in handling and use.

Types of Potassium Chromate

Marketed mainly for research, Potassium Chromate is available in various capacities and also as an aqueous solution, suitable for room-temperature storage and transportation.

What Is a Busbar?

A busbar is a copper bar used in control panels and power receiving panels.

Busbars are described as “BUS” in electrical drawings, etc., and are used in control panels by being fixed to insulators, etc. Unlike cables, bus bars have low flexibility and are used in locations where dimensions are clearly defined in advance.

Busbars have a higher allowable current than cables because they do not use organic materials as sheathing, have a higher allowable temperature, use a larger amount of copper, and have a larger cross-sectional area.

Uses of Busbars

Busbars can be used in a wide range of situations in production plants.

For example, it is used as an alternative to the main trunk wiring in control panels for industrial equipment. Busbars have a high allowable current and can easily be tapped off to create branch wiring, making them excellent as main trunks. For the same reason, it can also be used as a wireway for power-receiving panels.

It is also used as a conduit in high-current equipment for electrolytic refining. It is stronger than cable, has no sheath, thus reducing the amount of material, and has a higher allowable current.

Principle of Busbars

The structure of a busbar is simple, consisting of bare copper plates laminated together. They are mainly made of copper to supply high currents with low loss. This is because copper has extremely high conductivity among metals and is relatively inexpensive and readily available. The main metal with higher conductivity than copper is silver, which improves conductivity by about 6%. However, silver is by far the most expensive metal compared to copper, costing about 100 times more by weight.

In addition, busbars do not have a sheath and are always in contact with the outside air, which allows them to dissipate heat very well. Therefore, copper bus bars are the best choice for supplying large currents.

Types of Busbars

Busbars are mainly made of copper and are also called copper bars.

1. Tough Pitch Copper

The most widely distributed type of copper bar, this material has a copper purity of 99.90% or higher and an oxygen content of 80 ppm. It has excellent ductility, electrical conductivity, and durability, and is used for electrical components such as switchboards and in the chemical industry.

2. Oxygen-Free Copper

A material with a copper purity of 99.96% or higher, with an oxygen content of 10 ppm or less. When used at high temperatures, hydrogen and oxygen react and hydrogen embrittlement is likely to occur. Hydrogen embrittlement is a phenomenon in which the toughness and ductility of a material decrease due to hydrogen absorbed in the material.

This material is used when brazing or welding is required or when it is subjected to high heat during processing or use. However, it has poor distributability and is expensive.

3. Aluminum

Copper is generally used for busbars, but aluminum is also used in addition to copper. Aluminum has lower tensile strength and conductivity than copper, and its conductor volume is larger. However, due to its lower price and lighter weight, aluminum busbars can be used to reduce costs and weight.

How to Choose Busbars

The advantages of using busbars are many.

1. Cross Sectional Area

Busbars are manufactured from metal in the form of thick plates. Since the cross-sectional area is larger than that of a conductor and the capacity is also larger, a large current can flow.

2. Heat Dissipation

Since there is no insulating film, heat dissipation is higher than that of conductors.

3. Ease of Installation

Exclusively designed bus bars can be installed as they are, and general-purpose bus bars can be installed with Y-shaped or round terminals without terminal treatment.

4. Branching

Fixed with bolts or screws, terminals can be stacked or crossed. Screw holes can be placed along the way for efficient branching.

5. Other Advantages

High-frequency currents generated by switching affect malfunctions and noise. Bus bars with a large surface area reduce the effects of high-frequency currents.

Easy installation due to dedicated design, eliminating the need for terminal processing. Inexpensive materials reduce the manufacturing cost of distribution boards and control panels.

Structure of Busbars

A busbar is fabricated through the following processes:

1. Drilling

A hole is drilled in the required location in the metal plate. If necessary, threads are made by tapping.

2. Bending

After drilling, bending is performed using a press or bender, and edge-wise bending or flat-wise bending is performed according to needs. Edge-wise bending is done in the width direction, while flat-wise bending is done in the thickness direction.

What Is Butyl Rubber?

Butyl rubber is a type of synthetic rubber prepared by copolymerizing isobutylene and isoprene and is used in products around us. It was first developed by Standard Oil Company in the United States in 1937 using petroleum as the raw material. There are various types of butyl rubber depending on the addition of additives. The most suitable butyl rubber is produced according to the characteristics of the product to be used.

Uses of Butyl Rubber

Butyl rubber is used in a wide range of applications. Mainly in the automotive field, butyl rubber is used as raw material for tire tubes, hoses, and belts. Other industrial products include wire sheathing, rubber for window frames, and sports applications such as soccer balls and basketballs. Looking at product trends, butyl rubber is used in areas subject to high levels of tension, impact, and wear, and is particularly applied to products that require a certain level of strength.

Characteristics of Butyl Rubber

Butyl rubber is synthesized by copolymerizing isobutylene with isoprene. One particularly useful property of this rubber is its resistance to air permeation, which is about one-tenth that of natural rubber, styrene rubber, and butadiene rubber. This property of air permeability makes it an ideal raw material for tires, balls, and other products that require air to be stored inside the rubber and kept from leaking out through permeation. Butyl rubber also has excellent heat resistance, aging resistance, chemical resistance, acid/alkali resistance, and electrical insulation properties. It is used for the following purposes:

1. Applications where heat resistance is expected: condenser packing, steam hose material.
2. Applications where weather resistance and aging resistance are expected.
   Waterproof materials for construction, sheets, and adhesives for waste disposal ponds.
3. Applications where chemical, acid, and alkali resistance is expected.
   Rubber stoppers for pharmaceuticals, rubber gloves, rubber hoses, and industrial goods.
4. Applications expected to have electrical insulation properties:
   Wire sheathing, insulating tape.
5. Applications where air permeability is expected:
   Tires, sports balls

Butyl Rubber Disadvantages and Countermeasures

Butyl rubber is inferior to natural rubber in terms of elasticity, workability, and oil resistance, and its poor compatibility with other synthetic rubbers makes it difficult to develop rubber materials with new functions by mixing them. To solve these disadvantages, various types of butyl rubber have been synthesized by controlling the amount of isoprene during synthesis to change the degree of unsaturation, adjusting viscosity, and adding anti-aging agents.

About Halogenated Butyl Rubber

Butyl rubber has a slow vulcanization rate, is difficult to co-vulcanize with other highly unsaturated rubbers, and has poor adhesion to other rubbers and metals. To overcome these drawbacks, halogenated butyl rubber was developed by introducing chlorine and bromine atoms into the butyl rubber molecule. These halogenated butyl rubber contain highly reactive halogen molecules and double bonds in the molecule, and it has been reported that their vulcanization speed is faster and their vulcanization degree is greater than that of general butyl rubber.

What Is a Fluoropolymer Resin?

A fluoropolymer resin is a generic term for resins that contain fluorine in their main chain chemical structure. Due to the strength of the carbon-fluorine bond, they exhibit excellent heat resistance, flame resistance, chemical resistance, and weather resistance. In addition, it also has excellent properties, such as low friction, water repellency, and non-adhesiveness. However, fluoropolymer resin is more expensive than other resins.

Examples of fluoropolymer resin include PTFE, PFA, ETFE, PVDF, and various other resins with different chemical structures. Each of these resins has different heat resistance and processability. The most suitable fluoropolymer resin is selected according to the desired function, operating environment, and processing conditions.

Uses of Fluoropolymer Resins

Fluoropolymer resins are a generic term for polymers that contain fluorine in their main chain chemical structure. Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and perfluoroalkoxyalkane (PFA) are examples.

Compared to other resins, such as polyethylene and polypropylene, fluoropolymer resins have superior heat resistance, chemical resistance, weather resistance, and low friction. Taking advantage of these characteristics, fluoropolymer resins are used in various applications, including sealing materials, electric wires, corrosion-resistant linings, and automobile fuel lines. In addition, fluoropolymer resins are sometimes used to coat metal surfaces with fluoropolymers, such as the Teflon coating on the surface of frying pans, in order to achieve their fluoropolymer resins functionality.

Types of Fluoropolymer Resins

As mentioned above, fluoropolymer resins are a generic term for a number of resins with different chemical structures. Examples of specific resins include PTFE, which contains only carbon and fluoropolymer atoms and has extremely high chemical resistance and flame resistance; PFA, which has the same properties as PTFE resin but can be melt-molded; and ethylene tetrafluoropolymer resins, which maintain stable mechanical properties in a wide temperature range of -200°C to 150°C and have excellent weather resistance. Ethylene tetrafluoroethylene (ETFE), maintains stable mechanical properties over a wide temperature range from -200°C to 150°C and has excellent weather resistance.

Each of the fluoropolymer resins has a different chemical structure and, therefore, different properties. For example, PTFE has a very high melt viscosity. As a result, it is formed by compressing the powder and then sintering it. On the other hand, other fluoropolymer resins, such as PFA, can be melt-molded. In addition, mechanical strength and thermal stability also vary with different resins, so it is necessary to select the appropriate fluoropolymer resins based on the required properties.

Characteristics of Fluoropolymer Resins

Fluoropolymer resins have carbon-fluorine bonds. Carbon-fluorine bonds are very strong and are not easily broken. Therefore, fluoropolymer resins have superior heat resistance, flame resistance, chemical resistance, and UV resistance compared to other resins.

In addition, fluoropolymer resins also have excellent low dielectric and insulating properties, as well as low friction and water repellency. On the other hand, fluoropolymer resins are more expensive than other resins and have the disadvantage of limited processing methods.

What Is a Plier?

A plier is a type of tool. They are mainly used to get a firm grip on metal products.

Pliers come in more than 100 different shapes and sizes, depending on their application. Water pump pliers, combination pliers, and cutting pliers are commonly used.

When the word “pliers” is used, combination pliers are the ones that come to mind. They are easy to grip with one hand and are highly versatile tools.

Water pump pliers are also called Anguilla. Anguilla is a trade name, but it is more commonly used in production.

Cutting pliers are used for electrical work.

Uses of Pliers

Pliers are used at production sites.

For example, they are used for turning screws. Generally, screws have a slot cut in the head to insert a screwdriver. However, this slot may be filled due to corrosion or rust. In addition, a screwdriver larger than the slot diameter may be used to open up the slot. Alternatively, pliers can be used to grip and turn such screws because they can grip more firmly and apply more force than human force.

Pliers are used in various applications, depending on the type of pliers and the situation in which they are used.

Principle of Pliers

Different types of pliers have some things in common and some things that are different.

In general, all types of pliers are made of steel. This is because they need to be strong enough to grip and bend metal products. They are also designed to be handled manually. Electric pliers are very rare.

Another common feature is that the moving parts are small in relation to the handle. This is to obtain a strong torque by the principle of leverage. Also, the end of the movable part is grooved to apply strong pressure when gripped.

The difference is that cutting pliers, as the name implies, have a blade. In addition to being used as pliers, they can also be used to cut wires and strip wire sheathing.

With water pump pliers, the movable part is at an angle to the handle. Also, the width of the gripping area can be changed by shifting the fulcrum. They are used for water pipework since they can firmly grip screwed-in pipes. Among pliers, this type is used for gripping large metal products.

What Is a Flask?

A flask is a container for temporarily storing chemicals used primarily in chemical experiments or for mixing, reacting, heating, or distilling chemicals.

The main types of flasks include triangular flasks, Nas flasks, and female flasks, with the triangular flask being the most famous because it is used in elementary school science experiments.

Generally, these flasks are made of glass to prevent reactions with the chemicals in the container. Other materials such as metal and synthetic resin are also available but are less commonly used.

Uses of Flasks

Flask uses include chemical reactions, heating, and distillation, and the appropriate flask is selected depending on the application.

Like beakers, they can be used to store chemicals, but they are not suitable for long-term storage and can only be used for a few hours. A triangular flask with a co-stopper can be used to seal the entrance with a stopper, allowing the chemicals to be mixed with a wave of the hand. Magnetic stirrers can be used to mix chemicals with automatic stirring.

Features of Flasks

There are numerous types of flasks with different characteristics.

1. Triangular Flask

This is an orthodox flask. The entrance is narrow and the girth widens at the bottom to form a triangular shape. Since the entrance is smaller than that of a beaker, it prevents evaporation from the surface of the liquid and prevents the liquid from splashing out, making it easy to hold by hand and go down.

2. Eggplant Flask

The bottom of the flask is spherical, resembling the vegetable eggplant. It is often used in distillation tests such as rotary evaporators because it is easy to scrape out solid compounds and viscous liquids remaining in the flask from solvent distillation.

3. Female Flask

This is a weighing flask with a nearly triangular body and a 15 cm long, narrow entrance tube at the top. The volume is marked on a line at the top of the tube, and when liquid is added to the marked line, the volume indicated on the body can be weighed. Since the weighing error is 0.25 mL or less, it is used for dilution of chemicals with purified water.

4. Cassia Flask

It has a longer neck than the female flask. It has a scale on the neck.

5. Round Bottom Flask

This is a spherical flask with a mortised neck. The glass is thick-walled to withstand impact and pressure from chemical reactions.

6. Sakaguchi Flask

The top part has a long neck and the bottom part is hemispherical and is used for reciprocating shaking culture. It has a high airflow rate and prevents droplets from rising during shaking. However, the special shape makes it difficult to clean inside.

7. Swan-Neck Flask

The neck of the flask is long and bent into an S-shape. This structure does not stop steam or air from entering or leaving the flask and prevents dust and other contaminants from entering the flask.

8. Kjeldahl Flask

This is a long-necked type of Nas flask. It is used when chemicals are decomposed inside to cause reactions.

9. Branch Flask

This flask is used for distillation by incorporating it into a distillation apparatus. A glass tube protrudes from the long neck of the round-bottom flask.

10. Two-Branch Flask

A two-necked flask has two openings for the insertion of a thermometer and the feeding of chemicals. Three-necked flasks with three mouths and four-necked flasks with four mouths are also available depending on the application.

11. Separable Flask

Separable flasks are flasks with only the body. The mouth part is attached with a separable cover or clamp. It is easy to clean and the number of mouthfuls can be changed by changing the cover.

12. Flask for Soxhlet Extractor

This flask is used for the Soxhlet extractor.

Types of Flasks

There are several types of triangular flasks.

1. Triangular Flask With a Stopper

This is a triangular flask with a glass stopper that is fitted into the neck of the flask. The contents can be mixed by shaking the flask vigorously by hand.

2. Triangular Flask With Baffle

This flask has a projection inside and is often used for culturing microorganisms. Aeration of the liquid medium is increased by swirling and shaking. Cotton stoppers and silicone stoppers prevent contamination and ensure aeration.

3. Iodine Flask

A triangular flask with a co-stopper has a structure that stores liquid above the stopper and the mortise and tenon. It is used for the determination of iodine value, etc.

4. Buchner Flask

A thick-walled triangular flask with a short glass tube protruding from the neck. It is mainly used for suction filtration, and the inside of the flask can be depressurized by connecting the tube to a vacuum source such as a vacuum pump.