月: 2023年1月

What Is Calcium Carbonate?

Calcium carbonate, an alkaline metal carbonate with the formula CaCO₃, is used in various applications from building materials to medical antacids. It is known for being virtually insoluble in water but soluble in acidic solutions, making it useful for agricultural soil conditioning and as a safe snow-melting agent due to its minimal impact on living organisms.

Uses of Calcium Carbonate

Its uses span construction, as a filler in various industries, as a pH adjuster, and in consumer products like toothpaste and erasers. Medically, it serves as an antacid, and agriculturally, it helps neutralize acidic soils.

Properties of Calcium Carbonate

An odorless white powder, calcium carbonate exists in different crystal forms, with limestone being its main raw material. It slightly dissolves in carbon dioxide-rich water to form calcium bicarbonate, and it’s also soluble in acids.

Types of Calcium Carbonate

It is categorized into heavy calcium carbonate (natural) and light calcium carbonate (synthetic or precipitated), each produced through distinct processes.

Other Information on Calcium Carbonate

1. How Calcium Carbonate Is Produced

Production involves calcination of limestone to form quicklime, hydration to form slaked lime, and carbonation to precipitate calcium carbonate. The end product is dried and commercialized as light calcium carbonate.

2. Precipitated Calcium Carbonate

This synthetic form, also known as agglutinated calcium carbonate, is finely particulate and often surface-modified for enhanced performance in fillers and other applications.

What Is Ethylene Carbonate?

Ethylene carbonate is the cyclic ester of ethylene glycol and carbonic acid. Its chemical formula is C3H4O3, and its molecular weight is 88.06.

At room temperature (25 °C), ethylene carbonate is a clear glassy solid with a low melting point of 34-37 °C. In its liquid form, it is colorless and odorless. There are many known methods for synthesizing ethylene carbonate.

The most commonly used industrial method involves the reaction of ethylene glycol with phosgene. However, due to environmental impact concerns, research on phosgene-free synthesis methods has been progressing in recent years.

Uses of Ethylene Carbonate

Ethylene carbonate is widely used as an organic solvent. It is a highly polar solvent that can dissolve large amounts of electrolytes, making it particularly useful as a solvent in electrolyte solutions for lithium-ion secondary batteries.

Additionally, ethylene carbonate has gained industrial use as an excellent solvent for polymerization. Similar to ethylene oxide and ethyleneimine, it can undergo ring-opening addition reactions or condensation reactions with compounds containing active hydrogen, which are important for synthesizing polymers. This aspect of ethylene carbonate has attracted significant attention in the field.

What Is Ammonium Carbonate?

Ammonium carbonate, an ammonium salt of carbonic acid with the formula (NH₄)₂CO₃, is known only in its monohydrate form. It is commercially produced through the sublimation of a heated mixture of calcium carbonate and ammonium sulfate, resulting in a compound salt of ammonium hydrogen carbonate and ammonium carbamate.

Uses of Ammonium Carbonate

Used in the manufacture of various ammonium salts, as an analytical reagent, and in pharmaceuticals, ammonium carbonate serves diverse roles. Traditionally known as baker’s ammonia, it has applications in baking, as well as in creating foaming agents and adhesives.

Properties of Ammonium Carbonate

With a CAS No. of 506-87-6, ammonium carbonate appears as a white, crystalline powder with a characteristic ammonia odor. Soluble in water and basic in aqueous solutions, it decomposes upon heating to produce carbon monoxide, carbon dioxide, and ammonia.

Other Information on Ammonium Carbonate

1. Safety

Classified for skin and eye irritation and specific target organ toxicity, ammonium carbonate requires careful handling to avoid irritation and toxicity risks. Storage recommendations include a cool, well-ventilated place and avoidance of direct sunlight and oxidizing agents.

2. First Aid Measures

Recommendations for exposure include moving to fresh air, washing exposed skin or eyes thoroughly, and seeking immediate medical attention for ingestion or severe exposure.

3. Handling Methods

Appropriate handling measures include local exhaust ventilation, use of personal protective equipment, and the provision of safety facilities for emergency decontamination.

4. Market Size

The demand for ammonium carbonate spans food, pharmaceutical, and industrial applications, with significant growth in developing economies and steady demand in North America and Europe for specialized uses.

What Is Calcium Carbide?

Calcium carbide, a grayish-white solid with the formula CaC₂ and a molecular weight of 64.10, was first recognized for its ability to produce acetylene and calcium hydroxide upon reaction with water by Friedrich Wöhler in 1862. Known commercially as carbide, it is commonly used to generate acetylene gas.

Properties of Calcium Carbide

With a melting point of approximately 2,300°C and a density of 2.22, calcium carbide’s crystal form is tetragonal at room temperature. Its structure comprises calcium ions and acetylide ions, transforming to a cubic system at 450°C. Pure calcium carbide is colorless, though commercial varieties are gray or brown due to impurities, consisting mainly of CaC₂.

Uses of Calcium Carbide

Primarily, calcium carbide is used to produce acetylene gas for industrial purposes, including lime nitrogen fertilizers and acetylene burners. It has historical significance in organic compound synthesis and is used in steelmaking as a desulfurizing agent.

Other Information on Calcium Carbide

1. Manufacturing Process

Produced by heating coke and quicklime in an electric furnace, the method for creating calcium carbide was discovered independently by T.L. Wilson and H. Moissant in 1892.

2. Reaction with Water and Nitrogen

Calcium carbide reacts with water to produce acetylene and with nitrogen to form calcium cyanamide, a fertilizer, demonstrating its ability to cleave the triple bond of nitrogen at high temperatures.

3. Regulatory Information

Calcium carbide is recognized as a hazardous material, necessitating careful handling due to its potential for violent reactions with water and combustibility.

4. Handling and Storage Precautions

• Store in a cool, ventilated area away from moisture and direct sunlight.
• Use in well-ventilated or outdoor areas to avoid explosive reactions with water.
• Avoid contact with substances that could ignite or cause explosions.
• Employ protective gear during handling and ensure thorough washing post-use.

What Is Calcium Hydride?

Calcium hydride, with the formula H₂Ca, is primarily a gray powder, though it can appear as white crystals when pure. It is designated for research and development uses only, excluding pharmaceutical, household, or other applications.

Produced by reacting calcium with hydrogen at temperatures between 300°C to 400°C in the presence of hydrogen and sodium chloride, or through the reaction of calcium chloride with hydrogen and sodium metal, calcium hydride is a versatile compound.

Uses of Calcium Hydride

1. Desiccant

As a relatively mild desiccant, calcium hydride is preferred for handling safety over more reactive alternatives. It’s utilized for drying basic solvents and as a preparatory drying step before employing more potent desiccants.

2. Hydrogen Production

Traditionally, calcium hydride has been a source of hydrogen for both industrial and experimental applications, including safe methods to inflate balloons and determine the water content in diesel fuel through the hydrogen produced.

3. Reducing Agent

Effective in reducing various metals into their powder forms at temperatures between 600 and 1,000 °C, calcium hydride serves as a powerful reducing agent.

Properties of Calcium Hydride

1. Physical Properties

With a molecular weight of 42.09 g/mol and a CAS number of 7789-78-8, calcium hydride is an odorless light gray powder. It has a melting point of 816°C and decomposes at temperatures above 600°C, exhibiting a non-flammable nature under normal conditions but posing a dust explosion risk when finely dispersed.

2. Chemical Properties

While chemically stable under normal atmospheric conditions, calcium hydride reacts violently with water, alcohols, halogens, and certain acids, potentially leading to combustion or explosion.

Other Information on Calcium Hydride

1. Safety

Calcium hydride requires careful handling to avoid violent reactions with water and air moisture. It’s an irritant to the skin and eyes and necessitates careful disposal and handling.

2. First Aid Measures

For skin or eye contact, immediate rinsing with water is advised. In cases of inhalation, move to fresh air, and if ingested, drink water and seek medical attention promptly, providing SDS information to the physician.

3. Handling Instructions

Handling should involve protective gear and measures to prevent dust generation, with operations ideally conducted under inert gas to avoid moisture contact. Contaminated clothing should be changed, and thorough washing is recommended post-handling.

4. Storage

Store in a dry, tightly sealed container away from heat and ignition sources, ensuring no contact with water to prevent the release of flammable gases.

What Is Calcium Hydroxide?

Calcium hydroxide, known as slaked lime, is a calcium hydroxide with various applications. Its aqueous solution, referred to as lime water, acts as a reagent to detect carbon dioxide.

Found naturally as portlandite, calcium hydroxide is produced industrially via the dry digestion method, involving the addition of water to calcium oxide, followed by digestion and evaporation of excess water.

Uses of Calcium Hydroxide

Primarily used as a coagulant in konjac, calcium hydroxide also adjusts pH levels in sugar and processed meats. In construction, it serves as a material for plaster and mortar. In leather manufacturing, its suspension, lime milk, treats hide surfaces. Additionally, it’s utilized in root canal treatments, as a neutralizer for waste gas and wastewater, and in agriculture to amend acidic soils and maintain sanitary conditions in livestock barns.

Properties of Calcium Hydroxide

This substance appears as a colorless crystal or white powder, soluble in glycerin but nearly insoluble in ethanol and ether. Its slight water solubility results in a strongly alkaline solution or suspension, though it is less soluble than alkali metal hydroxides, demonstrating weak basic action. The dissolution heat is exothermic, with solubility diminishing as temperature rises.

Despite being a strong base, calcium hydroxide is not considered a deleterious substance. It undergoes neutralization reactions with acids, such as the production of calcium chloride and water when reacting with hydrochloric acid.

Structure of Calcium Hydroxide

Calcium hydroxide forms an ionic crystal of hydroxide and calcium ions, creating hexagonal platelet crystals in water. Its formula is Ca(OH)₂, with a molar mass of 74.0927 g/mol and a density of 2.211 g/cm³.

Other Information on Calcium Hydroxide

1. Reaction of Calcium Hydroxide

Blowing carbon dioxide into a saturated solution precipitates calcium carbonate, creating a cloudy white appearance. Excess carbon dioxide transforms calcium carbonate into soluble calcium bicarbonate, clearing the turbidity. Additionally, heating calcium hydroxide produces ammonia and decomposes at 580°C to calcium oxide. Chlorine absorption forms calcium hypochlorous acid.

2. Hazards of Calcium Hydroxide

Its aqueous solutions can harm mucous membranes and skin, posing severe risks to the eyes and potentially leading to blindness. Though neutralized by stomach acid, ingestion in large quantities can be harmful, affecting breathing, blood pressure, and organ function. Historically used in plague epidemics for its microorganism growth inhibition, safer calcium carbonate now replaces calcium hydroxide for creating white lines in schoolyards.

What Is Hypochlorous Acid?

Hypochlorous acid, an oxoacid of chlorine, emits a characteristic chalky odor.

Discovered in 1834 by French chemist Antoine Jerome Barrard, hypochlorous acid bears the chemical formula HClO, a molecular weight of 52.46, and a CAS number of 7790-92-3. It is a weak, unstable acid that exists solely in solution, prone to decomposition if not maintained.

Uses of Hypochlorous Acid

As a principal component of hypochlorous acid water, an electrolyzed water solution, hypochlorous acid serves as a disinfectant. It sterilizes vegetables, tableware, and facilities, combats cucumber powdery mildew and strawberry gray mold as a designated specific agricultural chemical, and sanitizes food factories, restaurants, and medical equipment like endoscopes.

Its utility extends to liquid sprays, wet wipes, and aerosols for disinfection, proving effective for indoor environments and mist and aerosol applications in disinfection chambers.

The sodium salt of hypochlorous acid, known for its bleaching capabilities, is employed in pulp bleaching and kitchen chlorine bleach.

Properties of Hypochlorous Acid

A potent oxidizer, hypochlorous acid is primarily used in bleaching and disinfection as unstable compounds like sodium hypochlorite.

Highlighted as a preventive measure against coronavirus infection, hypochlorous acid water is produced by electrolyzing a solution of sodium chloride or hydrochloric acid, featuring hypochlorous acid as its main component.

Other Information on Hypochlorous Acid

1. Production Process

Steam distillation of a neutralized hypochlorite solution, prepared by chlorine gas through a potassium hydroxide solution, yields hypochlorous acid in aqueous form. Advances in technology have facilitated affordable production and bottling for both home and commercial uses, with longevity enhanced by cool, sun-protected storage.

2. Chemical Reactions

In solution, hypochlorous acid partially dissociates into hypochlorous acid ClO⁻ and can react with HCl to produce chlorine, with ammonia to form monochloramine, with organic amines to generate N-chloramine, and with hydrogen peroxide to release oxygen. It also interacts with various biomolecules such as DNA, RNA, fatty acids, cholesterol, and proteins.

3. Regulatory Status

Not subject to regulations poisonous and deleterious substances, fire, or industrial safety and health laws.

4. Safety and Storage Guidelines

• Store in a cool, dark, ventilated area and use promptly to prevent decomposition and alkalinity shift.
• Decomposition accelerates upon exposure to sunlight, especially ultraviolet rays, or contact with organic substances.
• Avoid acids to prevent chlorine gas production.
• Ensure usage in open or well-ventilated spaces.
• Wear protective gloves and eyewear.
• Practice thorough handwashing post-handling.
• For skin contact, cleanse with soap and water; for eye contact, rinse with water for several minutes.

What Is Methyl Benzoate?

Methyl benzoate is a colorless liquid characterized by an aromatic odor.

Also known under the IUPAC designation methyl benzoate, this organic compound is alternately known as methylbenzoate, benzoic acid methyl ester, or Niobe oil.

With the chemical formula C₈H₈O₂ and a molecular weight of 136.15, its CAS registration number is 93-58-3. It is classified as a hazardous substance under various safety laws.

Uses of Methyl Benzoate

This ester compound, recognized for its fruity aroma, is naturally present in guava, mango, and kiwi fruit. It finds applications in food flavoring and the composition of ylang-ylang-based fragrances and perfumes due to its distinct aroma.

Additionally, methyl benzoate serves various purposes, including acting as a solvent for synthetic resins, cellulose esters, and rubber, assisting in the dyeing of polyester fibers, and as a component in fungicides and pesticides. Male orchid bees collect methyl benzoate from plants for use in pheromone synthesis.

In chemical synthesis, it serves as a precursor for:

• the selective synthesis of benzaldehyde via supported manganese oxide catalysts
• the Friedel-Crafts acylation reaction with aryl compounds to produce benzophenone derivatives

Properties of Methyl Benzoate

As a liquid, it has a melting point of -15°C, a boiling point of 199.6°C, a flash point of 82°C, and a density of 1.094 g/cm³ at room temperature. Its lipophilic nature allows for high solubility in ethanol and acetone, while it remains insoluble in water.

The reactivity of methyl benzoate varies, targeting either the ring or the ester groups based on the reactants employed. For instance, nitration with nitric acid under acidic conditions yields 3-nitro methyl benzoate. Similarly, its carbonyl carbon’s susceptibility to nucleophilic attack facilitates hydrolysis with NaOH solution to produce sodium benzoate.

Other Information on Methyl Benzoate

1. Production Methods

Methyl benzoate can be synthesized through Fischer’s esterification, reacting benzoic acid with methanol in the presence of a minimal amount of a strong acid catalyst, such as sulfuric acid.

Naturally, it is extracted from specific aquatic plants, like the Japanese pepper tree.

2. Safety Precautions and Storage

Handling
Being a flammable substance, methyl benzoate should be kept away from ignition sources such as high temperatures, open flames, and sparks. Its vapors may ignite from electrostatic discharge.

Appropriate grounding or other anti-static measures are advisable. Utilize in well-ventilated areas, preferably in a fume hood, and always wear personal protective equipment.

Fire Response
Thermal decomposition from fire can produce hazardous gases like carbon dioxide and carbon monoxide. Employ water spray, foam, powder extinguishers, carbon dioxide, or sand to combat fires.

Skin Contact
Avoid direct skin contact by wearing suitable protective clothing and gloves, ensuring that sleeves remain unrolled to prevent skin exposure.

In case of contact, cleanse with soap and ample water. Remove and isolate contaminated clothing. Seek medical advice if skin irritation develops.

Eye Contact
Use protective eyewear or goggles. If contact occurs, rinse your eyes thoroughly with water. Remove contact lenses if easily possible and continue rinsing. Seek medical attention if irritation persists.

Storage
Store in a glass container with a tight seal in a well-ventilated, cool location away from direct sunlight. Keep away from strong oxidizers.

What Is Hydrochloric Acid?

Hydrochloric acid is an aqueous solution of hydrogen chloride, represented by the chemical formula HCl. It is a colorless liquid with high acidity and has a strong pungent odor. Concentrated hydrochloric acid produces white smoke. Hydrochloric acid is also a major component of the gastric juices in most animals, including humans.

Hydrochloric acid is obtained by dissolving hydrogen chloride in water. Industrially, it is produced by reacting chlorine with hydrogen generated through the electrolysis of brine and then absorbing the resulting hydrogen chloride into water.

Concentrations of hydrochloric acid exceeding 10% are designated as deleterious substances.

Uses of Hydrochloric Acid

The main uses of hydrochloric acid are as a laboratory reagent and a food additive. In the laboratory, it is used to adjust the pH of solutions due to its strong acidic nature.

As a food additive, hydrochloric acid is used to saccharify starch, neutralize alkalinity, and prevent bacterial growth in alcoholic mashes.

Additionally, hydrochloric acid is employed in a wide range of applications, including as a cleaning agent for household and industrial purposes, for cleaning brick mortar, in the manufacture of pharmaceuticals and seasonings, and in removing rust from steel.

What Is Methyl Chloride?

Methyl chloride encompasses a group of compounds derived from methane (CH₄) through the substitution of hydrogen atoms with chlorine atoms, including chloromethane, dichloromethane, chloroform, and carbon tetrachloride. Noted for its strong, sweet aroma, methyl chloride is a notable halocarbon and an organic compound.

Uses of Methyl Chloride

Originally used as a refrigerant and solvent, the carcinogenic and ozone-depleting nature of methyl chloride has limited its industrial applications. However, it remains relevant in research and development for its solubility and stability properties.

Properties of Methyl Chloride Derivatives

• Chloromethane (CH₃Cl): A gas at room temperature, flammable, with a boiling point of -24.2°C.
• Dichloromethane (CH₂Cl₂): A colorless liquid used in laboratories, boiling at 40°C.
• Chloroform (CHCl₃): A colorless liquid with anesthetic properties, boiling at 61°C.
• Carbon Tetrachloride (CCl₄): A liquid used historically in NMR spectroscopy, boiling at 76.8°C.

Synthesis of Methyl Chloride Derivatives

Methods include treating benzyl alcohol with hydrochloric acid for chloromethane, photochemical reactions of toluene and chlorine for benzyl chloride, and chlorination of aromatic compounds with zinc chloride for benzyl chloride derivatives.

Reactions Involving Methyl Chloride Derivatives

Oxidation of benzyl chloride produces benzoic acid, while its reaction with sodium cyanide yields benzyl cyanide. Benzyl chloride can also be used to synthesize quaternary ammonium salts, and benzyl ethers, and protect hydroxy groups.

Regulatory Information and Health Effects

While chloromethane poses minimal carcinogenic risk, dichloromethane, chloroform, and carbon tetrachloride have been classified under GHS for their potential carcinogenicity. These substances require careful handling due to their health risks and potential to cause bile duct cancer among exposed workers.

Environmental Impact

Carbon tetrachloride, in particular, is regulated under the Montreal Protocol as an ozone-depleting substance, with its atmospheric breakdown contributing significantly to ozone layer depletion.