月: 2023年1月

What Is Aluminum Hydroxide?

Aluminum hydroxide, naturally found as gibbsite and diaspore, is created by reacting aqueous sodium aluminate with carbon dioxide or by neutralizing aluminum salt solutions with ammonia or alkali hydroxide. This amphoteric substance dissolves in strong acids and alkalis but becomes less soluble over time. When heated to 300°C, it dehydrates to form α-alumina.

Uses of Aluminum Hydroxide

Aluminum hydroxide serves various purposes, from being a primary ingredient in alumina and synthetic zeolite production to its use in ceramics, mordants, antacids, and textile waterproofing. It also functions as a filler in rubber, plastics, and paper to enhance fire resistance and whiteness. In pharmaceuticals, it’s utilized for its astringent qualities, in gas and liquid purification, as a chromatographic adsorbent, emulsifier, ion exchanger, and filtration material. Furthermore, it’s a key flame retardant in ceramic glass and is commonly used with aluminum phosphate as a vaccine adjuvant.

Properties of Aluminum Hydroxide

With a formula of Al(OH)₃ and a molecular weight of 78.00 g/mol, aluminum hydroxide appears as a white, amorphous powder. It has a density of 2.42 g/cm³ and a melting point of 300°C. This compound is soluble in methylamine but exhibits minimal solubility in water and is insoluble in acetone and ethanol. It gels upon extended contact with water and transforms into aluminum oxide upon heating, a reaction that releases water and contributes to its application in fire-resistant materials.

Other Information on Aluminum Hydroxide

1. Solubility of Aluminum Hydroxide

Aluminum hydroxide has a low solubility product (K_sp = 5×10^-33), but freshly precipitated gel forms dissolve easily in acids and bases. In basic solutions, it forms tetrahydroxidoaluminate ions ([Al(OH)₄]⁻) through coordination bonds, with a K_sp of 4×10^-13. Its solubility decreases in acidic conditions due to the reduced concentration of hydroxide ions. Over time, or when crystallized, its solubility in basic solutions diminishes.

2. Application of Aluminum Hydroxide

Aluminum hydroxide exists as α-type bayerite and γ-type gibbsite, with the latter being more stable at 25°C and 105 Pa. Under hydrothermal conditions, it dehydrates to form AlO(OH), a key component of bauxite. Both Al(OH)₃ and AlO(OH) lose water upon heating, facilitating the production of aluminum oxide (Al₂O₃).

What Is Sodium Hypochlorite?

Sodium hypochlorite is a white solid with the chemical formula NaClO, produced by the reaction of sodium hydroxide solution and chlorine gas. It is typically handled as an aqueous solution due to its instability when exposed to heat, light, and other stimuli. Sodium hydroxide is added as a stabilizer, and the pH is usually adjusted to 12 or higher, making the solution a clear, greenish-yellow liquid with a chlorine-like odor.

Uses of Sodium Hypochlorite

With its strong oxidizing power, sodium hypochlorite decomposes microorganisms and harmful substances. It is utilized across various sectors, including manufacturing, services, domestic settings, and other facilities.

1. Disinfection

Effective against numerous pathogens like norovirus, influenza, salmonella, and E. coli, sodium hypochlorite is a popular disinfectant. Its concentration can be adjusted by dilution, offering versatility in use. After oxidation, it leaves no toxic residues, making it safe for food industry disinfection and water treatment in pools and public baths.

2. Bleaching and More

As an oxidizing agent, sodium hypochlorite is used for bleaching in cleaning and paper industries and household cleaning products. It’s also used in various domestic and industrial applications, including mold decontamination, wastewater treatment, and odor elimination.

Characteristics of Sodium Hypochlorite

Figure 1. Hypochlorous Acid, Sodium Hypochlorite, and Hypochlorite Ions

Sodium hypochlorite, the sodium salt of hypochlorous acid, has an unstable high concentration and decomposes into sodium chloride and other substances over time. It is usually sold as a strongly alkaline solution with a 4-12% effective chlorine concentration.

Other Information on Sodium Hypochlorite

1. pH Dependence of Hypochlorous Acid Presence

At a pH of 12 or higher, sodium hypochlorite is mostly dissociated into hypochlorite and sodium ions. Dilution with water lowers the pH, increasing the proportion of hypochlorous acid, which has a significantly higher disinfection capability. A pH-adjusted dilution to achieve an effective chlorine concentration of 100 to 500 ppm is recommended for disinfection.

2. Dilution and Usage Concentrations

Follow the product-specific instructions for dilution and use. For self-dilution, use impurity-free water.

3. Effective Chlorine Concentration

Figure 3. Effective Chlorine Concentration for Various Applications

Disinfection and bleaching target	Guideline for effective chlorine concentration	Method of use, etc.
Raw vegetables and tableware	100ppm	Soak for 5 to 10 minutes
Cutting boards and knives	200ppm	Wipe clean
Sterilization of bathrooms, bathtubs, toilet bowls, etc.	500ppm	Wipe clean
Vomit and other contaminants	1%	Soak for 5 to 30 minutes
Water (drinking water)	0.1～0.4ppm	Residual chlorine concentration
Water (swimming pool, bath water)	0.4～1ppm	Residual chlorine concentration

4. Handling Precautions

Sodium hypochlorite solutions, while readily available, are highly alkaline and can cause chemical burns. Protective gear is recommended during use to prevent skin irritation and eye damage. Avoid transferring solutions to unsuitable containers and mixing them with acid detergents, as this can produce toxic chlorine gas.

5. Storage Guidelines

Store sodium hypochlorite in cool, dark, airtight, and non-corrosive containers to prevent decomposition. Ensure it is out of reach of children and regularly check the effective chlorine concentration if stored for more than three months to avoid using ineffective solutions.

What Is Sodium Hypophosphite?

Sodium hypophosphite, with the chemical formula NaPO₂H₂, is commonly known as sodium phosphosphosphite. It is predominantly sold in its monohydrate form, with the CAS registration number 10039-56-2.

Uses of Sodium Hypophosphite

Sodium hypophosphite is utilized in various applications, including as a reducing agent for electroless plating, a catalyst in synthetic resin production, and a pharmaceutical raw material. Its role in electroless nickel plating is particularly significant, offering improved corrosion resistance, wear resistance, and hardness to plated products, which are beneficial in semiconductor manufacturing and other industrial fields.

1. Electroless Plating

This method involves a redox reaction to deposit metal from a metallic salt solution without external electricity on a surface. Sodium hypophosphite along with boron and hydrazine compounds serves as a reducing agent, but it is the most commonly used in industrial settings.

2. Synthetic Field

As a reducing agent, sodium hypophosphite aids in chemical synthesis, such as producing nickel nanoparticles from nickel acetate tetrahydrate and facilitating enantioselective transfer hydrogenation of ketone compounds to alcohols.

Properties of Sodium Hypophosphite

The molecular weight is 87.98 for the anhydride and 105.99 for the monohydrate. It appears as a white crystalline powder at room temperature and is highly soluble in water, as well as in ethanol, glycerin, ethylene glycol, propylene glycol, and acetic acid. Its hygroscopic nature requires careful storage.

Types of Sodium Hypophosphite

Available as both a research and development reagent and an industrial chemical, sodium hypophosphite is primarily marketed in its monohydrate form for ease of handling in laboratories and industrial applications.

1. Reagent Products for Research and Development

For R&D purposes, it is offered in small quantities such as 25g, 100g, and 500g, suitable for laboratory use, and can be stored at room temperature.

2. Industrial Chemicals

In industrial settings, sodium hypophosphite is supplied in larger quantities like 25 kg flexible containers or 500 kg bags, catering to the needs of factories for electroless plating and as a pharmaceutical ingredient.

Other Information on Sodium Hypophosphite

1. Chemical Reaction of Sodium Hypophosphite

A strong reducing agent, especially in alkaline conditions, sodium hypophosphite oxidizes to phosphorous or phosphoric acid upon heating and can generate phosphine and hydrogen gases.

2. Precautions for Handling Sodium Hypophosphite

Although not classified under GHS or specifically regulated, it’s crucial to use protective measures such as ventilation, goggles, and protective clothing during handling to prevent skin and eye contact, emphasizing immediate washing if exposure occurs.

What Is Hypophosphorous Acid?

Hypophosphorous acid, with the molecular formula H₃PO₂, is known for its potent corrosive properties, capable of causing blindness and skin irritation upon contact. Its CAS registration number is 6303-21-5.

Uses of Hypophosphorous Acid

Valued for its reducing power, hypophosphorous acid’s primary applications include roles as a reducing agent in electroless plating, a catalyst in organic synthesis, a surface treatment agent, an antioxidant, and a thermal change inhibitor. It also serves as a bleaching and decolorizing agent for synthetic fibers and plastics and as a precursor for phosphinic acid salts and various substances used as dispersants, emulsifiers, and wet antistatic agents.

Properties of Hypophosphorous Acid

This inorganic acid has a molecular weight of 66.00, melts at 26.5°C, and boils at 130°C. Appearing as a clear, colorless oily liquid or solid at room temperature, its density is 1.493 g/mL and an acid dissociation constant (pKa) of 1.2. Hypophosphorous acid is soluble in water, alcohols, and ethers, and decomposes into phosphoric acid and phosphine when heated.

Types of Hypophosphorous Acid

Available as an industrial chemical and R&D reagent, hypophosphorous acid is sold in 30% or 50% solutions. Industrial grades often come in 25 kg polyethylene cans or 200 L drums, catering to various applications. For research purposes, smaller quantities such as 25g, 100g, and 500g solutions are common, with storage recommendations at room temperature.

Other Information on Hypophosphorous Acid

1. Synthesis of Hypophosphorous Acid

The synthesis involves boiling phosphorus in an alkaline solution to form a hypophosphorous acid solution. Precipitation of phosphorous acid salts as calcium salts removes them, followed by treatment with a non-oxidizing strong acid (e.g., sulfuric acid) to yield hypophosphorous acid.

2. Chemical Reaction of Hypophosphorous Acid

Hypophosphorous acid, favoring the HP(O)(OH)₂ tautomeric form for its stability, showcases its reducing power by converting chromium(III) oxide to chromium(II) oxide. Upon heating to about 110°C, it decomposes into phosphorous acid and phosphine. It reacts violently with alkaline substances and metals, necessitating careful storage away from high temperatures, sunlight, and moisture.

3. Hazardousness of Hypophosphorous Acid and Regulatory Information

Identified as hazardous, hypophosphorous acid can cause metal corrosion, serious skin burns, and eye damage. While not classified under specific laws, it is regulated as a corrosive substance for transportation and storage. Appropriate handling measures, including personal protective equipment, are essential to prevent skin, eye, and clothing contact.

What Is Uric Acid?

Uric acid is an organic compound with the chemical formula C₅H₄N₄O₃, having a molecular weight of 168.11. Also known as 2,6,8-trihydroxypurine, it appears as a white to slightly light brown powder and is insoluble in water. It is excreted as a nitrogen metabolism end product in birds, reptiles, and insects, and to a lesser extent in human urine as a nucleic acid metabolism product. Initially discovered in bladder stones, uric acid’s CAS number is 69-93-2 and is not classified as hazardous according to GHS criteria.

Uses of Uric Acid

Uric acid has applications in research and pharmaceutical fields. The blood uric acid level serves as an indicator of hyperuricemia, a condition arising from the body’s difficulty in excreting uric acid or overproduction. High purine intake can also elevate this risk. Hyperuricemia is diagnosed when uric acid levels exceed 7.0 mg/dL, while levels below 2 mg/dL indicate hypouricemia, a condition of excessive uric acid excretion or underproduction.

Properties of Uric Acid

Uric acid’s melting point exceeds 300°C. It is soluble in sodium hydroxide solutions but insoluble in ethanol and ether. The murexide reaction, turning an aqueous uric acid solution reddish-purple upon adding nitric acid and ammonia, confirms its presence. Excessive accumulation leads to urate crystal formation, triggering gout attacks. While uric acid acts as an antioxidant, it can promote oxidation under certain conditions.

Types of Uric Acid

Commercially, uric acid is available in various amounts, including 10 g, 25 g, 100 g, 500 g, and 1 kg options.

Other Information About Uric Acid

1. Production Pathway in the Body

Uric acid biosynthesis involves xanthine dehydrogenase, starting from ribose-5-phosphate to xanthine. The body’s production pathways are split into exogenous (dietary purines) and endogenous (cellular metabolism of nucleic acids and ATP), contributing to approximately 20-30% and 70-80% of produced uric acid, respectively. Daily human uric acid production is about 0.6 grams.

2. Relationship to Gout

Gout, characterized by uric acid crystal deposition in joints, leads to recurrent arthritis. It commonly affects the toes, insteps, knees, and elbows, among other joints. Gouty nodules, resulting from uric acid deposits, frequently occur on fingers, hands, feet, and elbows, and can also affect kidneys and the skin beneath the ears, potentially causing urinary tract stones in patients.

3. Association With Atherosclerosis

Epidemiological studies suggest a link between high uric acid levels and increased arteriosclerosis risk. Since 2020, uric acid salt deposition in arterial walls has been documented, potentially damaging vessel cells and contributing to atherosclerosis.

What Is Urea?

Figure 1. Basic Information on Urea

Urea, a nitrogen compound, is found in mammalian urine.

Known also as carbamide, urea decomposes into ammonia, cyanuric acid, and biuret when heated.

Urea can be synthesized through the hydrolysis of calcium cyanamide or dehydration of ammonium carbamate. It forms inclusion compounds with linear hydrocarbons and their derivatives, such as hexane. Its inclusion compounds with hydrogen peroxide are available commercially as solid-state oxidants.

Uses of Urea

Urea serves primarily as a fertilizer and urea resin raw material. It has applications as a diuretic, hypnotic, moisturizer, for extracting n-alkanes from petroleum, and in synthesizing hydrazine and melamine.

High-grade aqueous urea solutions purify nitrogen oxides in diesel and other vehicle emissions, known as the urea-SCR system.

In pharmaceuticals, urea is used for treating keratosis and dry skin, as a neuromuscular stimulant, and its aqueous solutions for evaluating protein solubilization and structural stability due to their protein denaturing properties.

Properties of Urea

Urea melts at approximately 133°C and decomposes to ammonia and other substances upon further heating. It is soluble in ethanol, insoluble in ether, and turns purple when mixed with copper sulfate in water, indicating an alkaline solution.

Urea is deliquescent and exhibits nonlinear optical phenomena, where its response to intense light is not directly proportional.

Structure of Urea

Figure 2. Urea Formation by Wöhler Synthesis

Urea, a colorless, odorless crystal with a molar mass of 60.06 g/mol (CO(NH₂)₂), was the first organic compound synthesized from inorganic materials, marking a milestone in organic chemistry history.

Friedrich Wöhler synthesized urea by heating ammonium cyanate, challenging the vitalism theory that only living organisms could produce organic compounds. The debate about whether urea is truly “organic” stems from its classification as an amide of carbonic acid, typically not considered an organic compound.

Other Information on Urea

1. Synthesis of Urea

Figure 3. Industrial Urea Synthesis Method

Beyond Wöhler synthesis, urea is industrially produced from carbon dioxide and ammonia under conditions exceeding 120°C and 150 atmospheres.

2. Excretion of Nitrogen by Urea

Mammals, cartilaginous fish, and amphibians excrete nitrogen in the form of urea. In humans, excess nitrogen from proteins is converted to urea via the urea cycle and excreted in urine. Bony fish excrete ammonia, while most birds and reptiles excrete uric acid, a purine metabolism end product in humans and many primates, and a less water-soluble alternative to urea.

3. Urea Excretion and Health

Adults excrete about 30 grams of urea daily. Excessive stress can increase uric acid production, leading to gout if excretion is insufficient and crystals form.

What Is Benzyl Benzoate?

Benzyl benzoate (C₁₄H₁₂O₂) is an ester of benzyl alcohol and benzoic acid, found naturally in some balsams and used extensively in medical and industrial applications. Classified for safe use as a flavoring agent, it’s also recognized for its pharmaceutical and insecticidal properties.

Uses of Benzyl Benzoate

Medically, it’s employed for its vasodilating effects and as a treatment for scabies and lice. Its insecticidal qualities make it effective against ticks and mosquitoes. Industrially, it’s used as a flavoring agent, a preservative in foods, a plasticizer for polymers, and a solvent in perfumes.

Properties of Benzyl Benzoate

This compound is a colorless or pale yellow liquid at room temperature, with a weak aromatic odor, a melting point of 17-20°C, and a boiling point of 323-324°C. It’s insoluble in water but soluble in ethanol, diethyl ether, and acetone.

Structure of Benzyl Benzoate

As a carboxylic acid ester, benzyl benzoate’s structure integrates benzyl alcohol and benzoic acid, contributing to its chemical stability and solubility in organic solvents.

Other Information on Benzyl Benzoate

1. Synthesis of Benzyl Benzoate

Produced through esterification or the Tishchenko reaction, its synthesis involves reacting benzyl alcohol with benzoic acid or catalytic disproportionation of benzaldehyde.

2. Hazards of Benzyl Benzoate

While generally safe, high doses can lead to adverse effects such as hyperexcitability and respiratory issues. Topical use may cause dermatitis or allergic reactions in some individuals.

What Is Benzoic Acid?

Benzoic acid (C₆H₅COOH) is a widely encountered aromatic carboxylic acid, appearing as a colorless crystalline solid. Found naturally in various fruits and plants, it’s recognized for its antiseptic properties and is utilized in a range of applications from food preservation to pharmaceuticals.

Uses of Benzoic Acid

Benzoic acid is employed as a preservative in foods, cosmetics, and pharmaceuticals, capitalizing on its ability to inhibit microbial growth. It serves as a mordant in dyeing processes, a rust inhibitor, and is instrumental in organic synthesis. In agriculture, it is added to livestock feed to promote growth. Notably, sodium benzoate, derived from benzoic acid, is extensively used as a food additive.

Properties of Benzoic Acid

This compound exhibits weak acidity, with a molecular weight of 122.13 and a melting point of 121.25°C. It’s insoluble in cold water but dissolves in hot water and various organic solvents. Benzoic acid is a strong oxidizer in acidic solutions and decomposes at elevated temperatures to release benzene and carbon dioxide among other products.

Structure of Benzoic Acid

Benzoic acid’s structure features a benzene ring attached to a carboxylic acid group, making it an important foundational molecule for further chemical reactions, including the formation of salts, esters, and amides.

Other Information on Benzoic Acid

How Benzoic Acid Is Produced

Historically extracted from natural sources, benzoic acid is now predominantly manufactured through the oxidation of toluene, a process that has overtaken earlier methods involving phthalic anhydride decarboxylation. The industrial synthesis of benzoic acid via toluene oxidation represents a significant method due to its efficiency and scalability.

What Is Sodium Chlorate?

Sodium chlorate (NaClO₃) is a potent oxidizer, widely recognized for its use in industrial chemicals, herbicides, and various manufacturing processes. It’s a colorless crystal, known for its explosive potential when mixed with flammable substances.

Uses of Sodium Chlorate

Its primary applications include the production of chlorine dioxide for pulp bleaching, sodium chlorite for textile bleaching, and as an effective non-selective herbicide. Sodium chlorate’s oxidizing properties also make it useful in dyeing, electrolytic processing, and as a component in matches, fireworks, and explosives.

Properties of Sodium Chlorate

NaClO₃ is highly soluble in water, with its solutions exhibiting neutral behavior. It decomposes under light, necessitating storage in dark, cool places. With a melting point of 248°C, it acts as a strong oxidizer, especially in acidic conditions, and decomposes at temperatures above 300°C.

Structure of Sodium Chlorate

As a colorless, odorless crystal, sodium chlorate features a +5 valent chlorine atom coordinated with three oxygen atoms. Its structure is crucial for its stability and reactivity.

Other Information on Sodium Chlorate

1. Synthesis of Sodium Chlorate

Produced primarily through the electrolysis of sodium chloride solutions, sodium chlorate formation is influenced by factors like electrode material, pH, and temperature. Laboratory methods also include the disproportionation of sodium hypochlorite.

2. Characteristics of Chlorates

Sodium chlorate is part of the broader family of chlorates, which includes other salts of chloric acid like potassium chlorate (KClO₃). These compounds share common chemical properties due to their oxidizing nature.

3. Related Compounds of Sodium Chlorate

Beyond chlorates, other chlorine oxoacids and their salts, such as hypochlorites, chlorites, and perchlorates, play significant roles in various chemical processes, each distinguished by the oxidation state of chlorine and its bonding structure.

What Is Potassium Chlorate?

Potassium chlorate (KClO₃) is an inorganic compound with oxidizing properties, widely used in explosives, matches, bleaches, and fireworks due to its ability to ignite mixtures with sulfur upon friction. It’s also utilized in various medical and pharmaceutical applications, including as a gargle solution.

Uses of Potassium Chlorate

Its oxidizing nature makes potassium chlorate a key component in ignition and combustion products. Additionally, it’s employed in the medical field as a gargle solution and in analytical reagents, printing inks, and water treatment as a disinfectant.

Properties of Potassium Chlorate

Appearing as a white crystal or powder, potassium chlorate has a melting point of 356°C and a slight solubility in water. It’s characterized by its odorless nature and insolubility in ethanol and acetone.

Types of Potassium Chlorate

Available primarily for research and industrial use, potassium chlorate is offered in various quantities, commonly stored at room temperature for ease of use in laboratories and industrial applications.

Other Information on Potassium Chlorate

1. Synthesis of Potassium Chlorate

Synthesized through the electrolysis of potassium chloride solutions, this process requires careful management of current density, concentration maintenance, and temperature control to prevent anode erosion and ensure efficient production.

2. Reactivity of Potassium Chlorate

Exhibiting strong oxidizing power, especially in acidic conditions, potassium chlorate decomposes to release oxygen when heated, making it a valuable source for oxygen generation in chemical reactions.

3. Hazardous Properties and Regulatory Information

Due to its reactivity, especially when mixed with flammable substances, potassium chlorate is classified under various safety laws as a deleterious and hazardous substance. Proper handling and storage are crucial to prevent accidental ignitions or explosions.