月: 2023年1月

What Is Cobalt Nitrate?

Cobalt nitrate, also known as cobalt (II) nitrate, is an inorganic compound found in various forms, including anhydrous, trihydrate, and hexahydrate, with the most commercially available form being hexahydrate. It is subject to multiple regulatory classifications due to its hazardous nature.

Uses of Cobalt Nitrate

Cobalt nitrate hexahydrate is utilized in several applications, such as a material for petrochemical and cobalt catalysts, in pigments for ceramics, for ablative inks, and as a test reagent. Additionally:

1. Rechargeable Batteries

It plays a critical role in the production of various rechargeable batteries, including nickel-cadmium, nickel-metal hydride, lithium-ion batteries, and fuel cells, by preventing corrosion of the positive electrode and serving as a conductor in nickel electrodes.

2. Surface Treatment

Cobalt nitrate is employed in plating chemicals and surface treatment agents, particularly for alloyed hot-dip galvanized steel sheets in automotive and construction materials, as well as for copper foil in printed circuit boards.

Properties of Cobalt Nitrate

The compound comes in anhydrous, trihydrate, and hexahydrate forms, each with distinct properties:

1. Anhydride

The anhydrous form, Co(NO₃)₂, is a red solid with a melting point of 100-105°C, produced through specific chemical reactions involving hexahydrate and dinitrogen pentoxide or by reacting silver nitrate with cobalt.

2. Hexahydrate

Cobalt nitrate hexahydrate, Co(NO₃)₂・6H₂O, is a red crystal that is deliquescent, easily soluble in water, and forms a reddish-brown acidic liquid in solution. It transitions between hexahydrate and trihydrate forms based on temperature.

This compound is not flammable but can act as a catalyst in the combustion of other substances due to its oxidizing properties.

Other Information About Cobalt Nitrate

1. Production

Cobalt nitrate is synthesized by reacting cobalt metal, oxide, hydroxide, or carbonate with dilute nitric acid, following specific chemical equations.

2. Safety Information

Handling cobalt nitrate requires protective gear, including masks, goggles, and gloves. It should be stored in airtight containers to prevent moisture absorption and kept away from combustible materials due to fire risk. Immediate medical attention is advised if it contacts the skin or eyes, or if inhaled or ingested.

What Is Aluminum Nitrate?

Aluminum nitrate, with the chemical formula Al(NO₃)₃, is a salt combining aluminum and nitrate ions. It has a molar mass of 213.0 g/mol, a melting point of 73°C, and a boiling point of 135°C. Among its various hydrates, aluminum nitrate nonahydrate (IX hydrate) is the most commonly used.

Properties of Aluminum Nitrate

Produced by dissolving aluminum in nitric acid and subsequent concentration, aluminum nitrate anhydrate appears as a colorless powder, while the nonahydrate form is a white solid with orthorhombic crystals. Aluminum nitrate acts as an oxidizing agent due to the nitrate ions, is soluble in water and ether, and forms weakly acidic aqueous solutions upon hydrolysis. Stable under standard conditions, it is hygroscopic and deliquescent, transitioning to its hydrate form when exposed to air. Handling requires caution due to its irritant nature, especially to the skin and eyes.

Uses of Aluminum Nitrate

1. Industrial Applications

Aluminum nitrate decomposes into aluminum oxide at temperatures between 1,200 and 1,300°C, a key process in producing aluminum oxide. In the leather industry, it serves as a tanning aid and finishing agent. As a mordant in dyeing, it forms water-insoluble dyes on fibers through the combination of aluminum ions with dye molecules. Its capacity to hold metals like cobalt aids in hydrogenation processes, being utilized as a catalyst in petroleum refining. Additionally, aluminum nitrate is used as a corrosion inhibitor or for metal surface treatment due to its ability to form a protective oxide layer.

It also finds a niche application as a uranium substitute in laboratory experiments related to uranium refining due to its similar crystal properties.

2. Organic Chemistry

In organic synthesis, aluminum nitrate is used to produce aluminum hydroxide by reacting with sodium hydroxide, exploiting its weakly basic nature. Its nitrosative properties allow for the nitrosation of benzene rings and other organic compounds, with nitrate ions serving as catalysts in various organic reactions.

3. Other Uses

Aluminum nitrate acts as an antiperspirant by reacting with sweat gland moisture, blocking the glands and reducing sweat secretion. It is also employed as an abrasive and analytical reagent for different substances.

Other Information on Aluminum Nitrate

Legal Information

Aluminum nitrate is classified as a hazardous and toxic substance under various safety laws, requiring specific labeling and notification, as well as being recognized for its oxidizing properties. It should be handled with appropriate care.

What Is Nitric Acid?

Nitric acid, represented by the chemical formula HNO₃, is a widely recognized strong acid. It poses significant hazards upon contact, capable of damaging skin, the digestive tract, and the respiratory system, necessitating careful handling.

Uses of Nitric Acid

Nitric acid’s applications span across various sectors such as agriculture, construction, military, industry, textiles, chemistry, and pharmaceuticals:

1. Fertilizer Production

As a critical nitrogen source, nitric acid is fundamental in creating fertilizers, alongside phosphoric acid and potassium, to enhance plant growth.

2. Explosive Materials

It is essential in synthesizing explosives like nitroglycerin, nitrocellulose, TNT, and picric acid, and serves as an oxidizing agent in rocket propellants due to its rapid decomposition with amines.

3. Miscellaneous Uses

Additionally, nitric acid is utilized in producing celluloid, dyes, pigments, electroplating solutions, dissolving metals, pharmaceuticals, synthetic fibers, toluene diisocyanate (for polyurethane), and adipic acid.

Properties of Nitric Acid

A colorless liquid with a molecular weight of 63.02 and a specific gravity of 1.502, nitric acid exhibits a light yellow tint and peculiar odor, fuming when exposed to air. It’s a potent acid and oxidizer, reacting aggressively with bases, decomposing under light, and corroding most metals except gold and platinum. Iron, chromium, and aluminum exhibit passivity against it. When heated, it decomposes, emitting toxic fumes and posing risks of violent reactions with flammable or reducing substances and organic compounds.

Other Information on Nitric Acid

Nitric Acid Production Methods

Nitric acid production predominantly employs the ammonia oxidation method (Ostwald process), consisting of ammonia oxidation to nitric oxide, nitric oxide oxidation to nitrogen dioxide, and nitrogen dioxide absorption in water:

1. Oxidation of Ammonia: Ammonia gas mixed with air passes through a platinum-rhodium catalyst, converting to nitrogen monoxide and water in an exothermic reaction with high yield.

2. Oxidation of Nitric Oxide: The nitric oxide is further oxidized to nitrogen dioxide, a step that benefits from the cooling process’s waste heat.

3. Absorption of Nitrogen Dioxide: Nitrogen dioxide reacts with water to produce nitric acid and nitric oxide, typically yielding 55-68% nitric acid, known as dilute nitric acid.

To concentrate nitric acid beyond 68%, water is removed by heating or using a dehydrating agent, overcoming azeotropic limitations.

What Is Acetic Anhydride?

Acetic anhydride, with the molecular formula C4H6O3 and specific formula (CH3CO)2O, is a colorless liquid. It reacts with water to form acetic acid and has a strong acetic acid odor when exposed to air moisture.

Pure acetic acid and glacial acetic acid, which have low water content, differ from acetic anhydride. Acetic anhydride is the simplest carboxylic anhydride to isolate and is a key raw material in organic synthesis, forming esters with alcohols and cellulose.

Properties of Acetic Anhydride

Acetic anhydride has a higher boiling point (139.8°C) than acetic acid (118°C) and can cause irritation and tearing when inhaled or if it contacts the skin. It should be handled with care, especially when heated.

Acetic anhydride hydrolyzes to form acetic acid, fully miscible in water:
(CH3CO)2O + H2O → 2 CH3COOH

Acetic Anhydride Manufacturing Process

First synthesized in 1852 by Charles Frédéric Gerhardt, acetic anhydride is now industrially produced by reacting ketene with acetic acid, or through the carbonylation of methyl acetate.
H2C=C=O + CH3COOH → (CH3CO)2O
CH3CO2CH3 + CO → (CH3CO)2O

Uses of Acetic Anhydride

Acetic anhydride is essential for acetylation in organic chemistry, introducing acetyl groups into various compounds.

Acetylation of Alcohols and Cellulose

Reacting with alcohols, it forms acetic esters (e.g., ethyl acetate from ethanol), and with cellulose, it yields acetyl cellulose used in a range of applications including cigarette filters and synthetic fibers.
(CH3CO)2O + CH3CH2OH → CH3CO2CH2CH3 + CH3COOH

Acetylation of Aromatic Rings

Acetic anhydride acetylates aromatic rings in the presence of an acid catalyst, as seen in the conversion of ferrocene to acetylferrocene.
(C5H5)2Fe + (CH3CO)2O → (C5H5)Fe(C5H4COCH3) + CH3COOH

Preparation of Other Acid Anhydrides

Acetic anhydride is also used to convert dicarboxylic acids into their corresponding anhydrides.

Additionally, acetic anhydride’s applications have expanded into new areas like polarizer protection film for LCDs, liquid crystal polymers, and urethane elastic fibers.

What Is Maleic Anhydride?

Maleic anhydride is a white crystalline substance produced by air oxidation of benzene or n-butane. It serves as a raw material for fumaric acid, which is a food additive, and is also used in unsaturated polyester resins, paint resins, and as a resin modifier.

Maleic anhydride, an acid anhydride, hydrolyzes readily in water to form maleic acid. It and its isomer fumaric acid are precursors for organic acids like malic acid and succinic acid.

This chemical is considered hazardous according to the 2012 OSHA Hazard Communication Standard. It is a skin and respiratory irritant and sensitizer, requiring careful handling and appropriate protective equipment.

Maleic Anhydride Manufacturing Process and Uses

Maleic anhydride is produced via the air oxidation of benzene and n-butane, commonly using vanadium oxide as a catalyst. Its applications include raw material for fumaric acid and unsaturated polyester resins and as a modifier for resins, paints, inks, and glue for coating paper surfaces.

Additionally, it modifies resins like polypropylene, used in fiberglass-reinforced plastics for various applications including housing, automotive, marine, and chemical equipment.

Examples of Reactions Using Maleic Anhydride

Maleic anhydride, a dehydrated and condensed form of two carboxylic acids, reacts with water to form maleic acid, which can isomerize to fumaric acid. At 160°C, maleic acid dehydrates back to maleic anhydride. It’s also a raw material for synthesizing malic and succinic acids, with industrial production of malic acid typically involving the hydration of fumaric acid under pressure.

Safety of Maleic Anhydride and Regulations

As a white crystal that sublimates with a pungent odor, maleic anhydride is not classified as hazardous under fire regulations due to its solid state. However, it is flammable with a flash point of 102°C. Proper storage and handling are crucial due to its hazardous nature.

What Is Phthalic Anhydride?

Phthalic anhydride, also known as 1,3-isobenzofurandione, is an acid anhydride derived from the dehydration-condensation of two carboxylic (carboxyl) groups in phthalic acid. This compound transforms back into phthalic acid upon exposure to moisture in the air.

Uses of Phthalic Anhydride

Phthalic anhydride is primarily used to produce phthalic acid diesters, such as dioctyl phthalate and dibutyl phthalate, which serve as plasticizers to soften plastics. It is also a key ingredient in the manufacturing of polyester resins, alkyd resins for synthetic resin paints, dyes like phenolphthalein, fluorescein, eosin, and raw materials for pharmaceuticals. These compounds are extensively utilized in products ranging from wallpaper and floor coverings to electrical wire insulation and PVC leather for furniture. In 2017, Japan produced over 160,000 tons, exporting about 50,000 tons internationally.

Properties of Phthalic Anhydride

With a molecular formula of C₈H₄O₃, phthalic anhydride is a pure white, needle-like crystalline powder or flake. It emits a slight pungent odor and has a density of 1.527 g/cm³, melting point of 130.8°C, boiling point of 284.5°C, flash point of 151.7°C, and ignition point of 570°C. It is soluble in alcohol, marginally soluble in ether and boiling water.

Other Information on Phthalic Anhydride

1. Production of Phthalic Anhydride

Phthalic anhydride is produced by the intramolecular dehydration of phthalic acid or by oxidizing naphthalene or ortho-xylene in the gas phase using vanadium pentoxide as a catalyst. The process can be categorized into fluidized-bed or fixed-bed methods, involving reaction, condensation, and distillation stages. The efficiency of this process results in approximately 85% yield of phthalic anhydride.

• Using Naphthalene: C₁₀H₈ + 4.5O₂ → C₈H₄O₃ + 2H₂O + 2CO₂
• Using Ortho-Xylene: C₆H₄(CH₃)₂ + 3O₂ → C₈H₄O₃ + 3H₂O

Vanadium-based catalysts are commonly used, supported on materials like silica, alumina, silicon carbide, or pumice stone, with the reaction occurring within 0.1 to 0.5 seconds at temperatures between 400 to 500℃.

2. Reactions Involving Phthalic Anhydride

Phthalic anhydride is instrumental in synthesizing phenolphthalein, a widely used acid-base indicator, through the intermolecular dehydration reaction of phthalic acid and phenol. It also serves as a protecting group for primary amine groups in organic synthesis.

3. Toxicity of Phthalate Plasticizers

The health and environmental impacts of phthalate plasticizers have been scrutinized, particularly in the 1990s and early 2000s. However, after over half a century of global usage, including in medical applications, the risks posed by phthalate plasticizers are considered manageable, with no immediate need for further regulation beyond current measures.

What Is Silver Carbonate?

Silver carbonate, with the chemical formula Ag₂CO₃, is also known as silver(I) carbonate due to the univalent state of silver in this compound.

It appears as a light yellow to yellow-green powder at room temperature and is synthesized by reacting silver nitrate with a water-soluble carbonate, such as ammonium carbonate.

The reaction typically occurs in an aqueous system, resulting in silver carbonate precipitating as a water-insoluble compound. Its molecular weight is 275.75, and it is identified by CAS number 534-16-7.

Uses of Silver Carbonate

1. As a Catalyst and Reagent

Silver carbonate serves primarily as a catalyst and reagent, including as a precursor for silver salts of organic acids, due to its solubility in organic solvents. Notably, it is used in Fétizon’s reagent, a mild oxidation catalyst, and for regioselective benzylation of carbohydrate derivatives, as well as in palladium-catalyzed oxyarylation of olefins. It also finds application in the staining of biological specimens for pathological tests.

2. In Silver Compounds

As a silver compound, it is utilized in metallic paints for silver mirror compositions and as a substitute for traditional solder in conductive adhesives (silver pastes).

3. As Photocatalysts

Leveraging its response to visible light, silver carbonate is used in the production of visible light-responsive semiconductors and photocatalysts.

Properties of Silver Carbonate

Silver carbonate is characterized by its light yellow to yellowish-green color, which darkens upon exposure to air and light due to partial oxidation. This sensitivity necessitates storage in light-protective conditions, often in brown bottles, to prevent degradation. It is virtually insoluble in water, requiring large volumes of water to dissolve, but dissolves readily in dilute nitric acid, sulfuric acid, ammonia water, and alkaline cyanide solutions. Decomposition occurs at 210-220°C, yielding silver oxide and carbon dioxide, and further heating produces metallic silver.

Other Information on Silver Carbonate

Toxicity, Hazards, and Regulations

Regulated under various safety laws due to its toxicity, silver carbonate necessitates protective equipment during handling. It reacts with strong oxidizers, posing additional safety considerations. In combustion, it produces carbon dioxide and, under incomplete combustion, carbon monoxide, alongside silver oxides, all of which are harmful to human health.

What Is Sparkling Water?

Sparkling water is a carbon dioxide (CO₂) aqueous solution.

Often referred to as carbonated water, sparkling water can be either natural or artificial. Natural sparkling water is groundwater enriched with carbon dioxide gas from its source, manifesting as hot springs or seeps. Conversely, artificial sparkling water involves dissolving carbon dioxide in water under pressure. The market offers both naturally carbonated water and purified water with added carbon dioxide.

Sparkling water is known for its refreshing, cooling sensation, gaining popularity for refreshment and various other purposes.

Uses of Sparkling Water

Primarily, sparkling water is served in beverages and hot baths. Other notable uses include:

1. Cooking Rice

Using sparkling water for cooking rice yields fluffy and flavorful grains due to carbonic acid forming air bubbles during cooking.

2. Cooking Food

Cooking with sparkling water ensures tender and flavorful stews without altering the taste of ingredients, as sparkling water itself is tasteless.

3. Cleaning Surfaces

Cleaning with sparkling water proves more effective than ordinary water, thanks to its ability to encapsulate and remove dirt through bubble formation. It’s ideal for cleaning lightly soiled surfaces, such as windows and floors, and is safe for homes with children and pets due to its detergent-free nature.

4. Hair Washing

Beauty salons increasingly offer carbonated head spas, utilizing carbonation to cleanse the scalp and alleviate issues like stickiness and odor while enhancing blood circulation.

Properties of Sparkling Water

Sparkling water exhibits the following characteristics:

1. Weakly Acidic

With a pH of 5.5 or lower, sparkling water is slightly acidic, resulting from carbon dioxide forming carbonic acid, which further dissociates to release hydrogen ions.

　(1) CO₂ + H₂O ⇄ H₂CO₃
　(2) H₂CO₃ ⇄ H⁺ + HCO₃^–

2. Effervescence

The effervescent nature of sparkling water is characterized by bubbling, especially evident when opening a PET bottle, as the pressure decrease causes dissolved carbon dioxide to form bubbles.

3. Sourness

Sparkling water’s carbonation stimulates taste buds sensitive to sourness, imparting a sour flavor.

4. Cooling Sensation

The tingling sensation in the mouth from sparkling water is attributed to carbonic anhydrase converting carbonic acid into hydrogen and bicarbonate ions, stimulating the trigeminal nerve.

5. Vasodilating Effect

Immersing in sparkling water is thought to increase prostaglandin E2 production, a vasodilator, thereby enhancing blood vessel dilation.

Types of Sparkling Water

Commercially, sparkling water for consumption is available as carbonated beverages, categorized as follows:

1. Natural Water-Based

This category includes naturally carbonated water, either containing carbon dioxide from the source or having carbon dioxide added to natural water, often rich in minerals like calcium and magnesium.

2. Pure Water-Based

Pure water-based sparkling water involves adding carbon dioxide to purified water, generally lacking in minerals, though they may be added subsequently.

3. Sweeteners and Flavors

Beyond carbonation, carbonated waters may include sweeteners, acidifiers, and flavors, offering a variety of tastes. However, high sugar content should be consumed with caution.

4. Carbonation Levels

Carbonated beverages vary in carbon dioxide content, classified as strongly or slightly carbonated, measured in gas volume (GV) units, with strongly carbonated drinks often having a GV of 5, known for their refreshing effect.

What Is Zinc Carbonate?

Zinc carbonate, a white powdery substance with a tetragonal crystal structure, is typically known as basic zinc carbonate. While its molecular formula is ZnCO3, the industry often uses the formula 2ZnCO3-3Zn(OH)2-H2O due to its variable composition. It occurs naturally in the form of rhyozinc ore and decomposes at 140°C to form zinc oxide and carbon dioxide.

Basic zinc carbonate is produced by reacting zinc salt solutions with alkali carbonates. It is virtually insoluble in water.

Uses of Zinc Carbonate

Zinc carbonate is used in various applications, such as a pigment in ceramics painting, an ingredient in pharmaceutical ointments, and as a food additive. It serves as a fire retardant for wood and other materials. Additionally, it is utilized in rubber compounding, galvanizing, as a catalyst, and in livestock feed to prevent zinc deficiency.

When zinc carbonate is heated, it yields zinc oxide, which is used in liquid crystal fluorescent tubes and as UV protection. Zinc plating on steel plates and frames helps prevent rust. Exposed zinc surfaces form a protective layer of zinc hydroxide, which oxidizes into zinc carbonate, contributing to its rust-preventive properties.

What Is Barium Carbonate?

Barium carbonate, a barium salt of carbonic acid, naturally occurs as witherite—a poisonous mineral found in hydrothermal deposits within limestone formations. In some regions, notably the United Kingdom, witherite has been used as a raw material for barium production. In Japan, barium carbonate is classified as a “deleterious substance,” regulated by multiple laws.

Uses of Barium Carbonate

Barium carbonate serves as a raw material in the manufacture of various barium salts, crystal glass, and cathode ray tubes. It’s also used in electrodes, paints, enamels, ceramic glazes, metal heat treatment, and paper production. Recently, it has found extensive use in electronic materials, particularly as a component in ceramic capacitors, PTC thermistors, optical glass, semiconductors, and phosphor materials. Its toxicity also lends it to use in insecticides and rodenticides.

Properties of Barium Carbonate

Insoluble in water but soluble in carbon dioxide-rich water, nitric acid, hydrochloric acid, and ethanol, barium carbonate has a melting point of 811°C and decomposes at 1,450°C in air. Its solubility in water at 20°C is notably low, at 0.0024 g/100 mL.

Structure of Barium Carbonate

Barium carbonate’s structure is comparable to potassium nitrate, with barium ions and carbonate ions mirroring the arrangement of potassium ions and nitrate ions, respectively. It exists in orthorhombic, amorphous, and hexagonal forms, transitioning between these states under specific temperature and pressure conditions. Its chemical formula is BaCO₃, with a molar mass of 197.34 g/mol and a density of 4.286 g/cm³.

Other Information on Barium Carbonate

1. Synthesis of Barium Carbonate

Barium carbonate can be synthesized by passing carbon dioxide through barium hydroxide or by adding alkali carbonate to an aqueous barium salt solution. Industrially, it’s produced from baryte through carbon reduction and carbon dioxide processing.

2. Hazards of Barium Carbonate

While barium carbonate can form toxic barium ions when dissolved in hydrochloric acid, it’s crucial in radiography to distinguish it from barium sulfate (BaSO₄), a non-toxic contrast agent. Misuse or misidentification can lead to serious health risks due to its toxicity.