月: 2023年1月

What Is Benzyl Chloride?

Benzyl chloride, also known as chloromethylbenzene or α-chlorotoluene, is an aromatic organic compound with the formula C₆H₅CH₂Cl. Recognized for its pungent odor and irritant properties, it’s classified as highly toxic and was listed as a nonmedicinal toxicant in Japan in 2016.

Uses of Benzyl Chloride

Historically used as tear gas, benzyl chloride now serves primarily in organic synthesis as a benzylating agent. It’s instrumental in the production of pharmaceuticals, fragrances, and dyes, acting as an intermediate and protecting agent for hydroxy groups in alcohols and phenols.

Properties of Benzyl Chloride

This colorless liquid is characterized by a strong odor and significant irritancy towards eyes, skin, and mucous membranes. It has a melting point of -39°C, boils at 179°C, and is incompatible with water while being soluble in organic solvents like chloroform and ether.

Structure of Benzyl Chloride

With a molecular structure derived from toluene by substituting a chlorine atom for one hydrogen in the methyl group, benzyl chloride has a molecular weight of 126.59 and a density of 1.100 g/cm³.

Other Information on Benzyl Chloride

1. Synthesis of Benzyl Chloride

Initially produced from benzyl alcohol and hydrochloric acid, industrial synthesis now primarily involves the gas-phase photochemical reaction of toluene with chlorine, generating around 100,000 tons annually. Alternative methods include Blanc chloromethylation from benzene, utilizing zinc chloride as a catalyst.

2. Reactions Involving Benzyl Chloride

Benzyl chloride undergoes various reactions, including oxidation to benzoic acid with KMnO₄, conversion to benzyl esters, cyanides, quaternary ammonium salts, and ethers through interactions with sodium cyanide, tertiary amines, and sodium hydroxide, respectively. It’s particularly useful for introducing benzyl-protecting groups in organic synthesis.

3. Related Compounds

Reacting readily with magnesium, benzyl chloride forms Grignard reagents, offering a preferable route over benzyl bromide for certain reactions due to its suitability in avoiding unwanted side reactions like the Wurtz-Fittig reaction.

What Is Sulfuryl Chloride?

Sulfuryl chloride, a colorless liquid with a pungent odor, is an inorganic compound identified by the chemical formula SO₂Cl₂, a molecular weight of 134.97, and CAS number 7791-25-5. Featuring a tetrahedral structure, it comprises two oxygen and two chlorine atoms bonded to a sulfur atom. Discovered by Henri-Victor Rigneau in 1838, it demonstrates significant industrial utility.

Uses of Sulfuryl Chloride

As a potent source of chlorine, sulfuryl chloride is employed in various chemical transformations, including the chlorination of alkanes, alkenes, alkynes, aromatic compounds, ethers, and epoxides. It’s particularly effective in converting C-H bonds adjacent to active substituents into C-Cl bonds and transforming thiols, disulfides, and alcohols into their chlorinated counterparts.

Properties of Sulfuryl Chloride

This compound melts at -54°C, boils at 69°C, and has a density of 1.67 g/cm³. Sensitive to temperature, it decomposes above 100°C, and its exposure to air results in the breakdown into sulfur dioxide and chlorine, often giving aged samples a yellowish-green tint.

Other Information About Sulfuryl Chloride

1. Production Process

Sulfuryl chloride is synthesized by reacting sulfur dioxide with chlorine in the presence of a catalyst like activated carbon, a process that can be refined through distillation. Historically, it was also produced by oxidizing thionyl chloride with agents like mercury oxide or manganese dioxide.

2. Reaction with Water

When reacting with water, sulfuryl chloride yields hydrogen chloride gas and sulfuric acid, showcasing its role as a chlorine source for various chlorination reactions.

3. Regulatory Information

Although not specifically regulated by major safety laws, sulfuryl chloride is considered a poisonous or toxic substance in maritime and aviation transport regulations, necessitating careful handling due to its toxicity and irritant properties.

4. Handling and Storage

Recommended practices include storage under inert gas in cool conditions, usage in well-ventilated areas or outdoors, and adherence to protective measures to mitigate risks from hydrolysis-induced pressure increases and violent reactions with incompatible materials.

What Is Choline Chloride?

Choline chloride is an organic compound classified as a quaternary ammonium salt with the chemical formula C5H14ClNO. It has a pivotal role in the body, either as a component of phospholipids or as the neurotransmitter acetylcholine, similar to its derivative, phosphatidylcholine.

While the body can synthesize choline, inadequate protein intake may lead to insufficient production, potentially resulting in a fatty liver.

Uses of Choline Chloride

Choline chloride is widely used in health food supplements and animal feeds, particularly in the poultry industry, reflecting its growing market. It is essential for maintaining cell membrane integrity, acting as a neurotransmitter via its conversion to acetylcholine, and serving as a methyl group donor through its metabolite, trimethylglycine (betaine), in the metabolic pathway for synthesizing S-adenosylmethionine.

Properties of Choline Chloride

This compound appears as a white crystal or crystalline mass with a characteristic odor, identified by CAS No. 67-48-1. It melts at 305°C and is highly soluble in water and ethanol, with sensitivity to light and hygroscopic properties. When handling, precautions are necessary due to the potential release of hazardous decomposition products like carbon monoxide, carbon dioxide, nitrogen oxides, and hydrogen chloride gas.

Other Information on Choline Chloride

1. Safety

While not classified under GHS, handling choline chloride requires caution and appropriate protective gear. Instructions cover procedures for inhalation, skin or eye contact, and ingestion, emphasizing immediate medical attention or thorough washing as needed.

2. Handling Instructions

Protective measures include using dust-proof respirators, gloves, and safety glasses. Workplaces should implement local exhaust ventilation and provide emergency wash stations.

3. Storage

Choline chloride should be stored in airtight glass containers in cool, well-ventilated areas, away from light and strong oxidizers, to prevent moisture absorption. Compliance with disposal regulations is also advised.

4. Fire Fighting Measures

In the event of a fire, various extinguishing media such as water spray, carbon dioxide, foam, or sand may be used, taking care to wear protective equipment due to the risk of toxic gases.

5. Market

The choline chloride market is projected to expand at a CAGR of 4.11% from 2021 to 2026, driven by demand from the livestock industry and its benefits as a human supplement for liver health, brain development, muscle metabolism, and nervous system function.

What Is Chromium Chloride?

Chromium chloride refers to a group of chemical compounds consisting of chromium and chlorine, with varying oxidation states: chromium(II) chloride, chromium(III) chloride, and chromium(IV) chloride.

Chromium(II) chloride is produced by reacting hot chromium metal with hydrogen chloride. Chromium(III) chloride forms when chromium metal is heated in a chlorine atmosphere. Chromium(IV) chloride, produced by heating chromium(III) chloride with chlorine at 600-700°C, is unstable and challenging to isolate.

Uses of Chromium Chloride

Chromium chloride catalyzes organic reactions, in chrome plating, and the manufacture of pigments, pharmaceuticals, and mordants. Specifically, chromium(II) chloride is essential in chrome plating technologies, enhancing corrosion resistance and surface hardness. In textiles, it helps bind dyes to fabrics. It is also used as a catalyst in olefin production and as a waterproofing agent.

Chromium(III) chloride plays a role in glucose metabolism, aiding in the activation of insulin-driven reactions, thus finding applications in pharmaceuticals for metabolic support.

Properties of Chromium Chloride

Chromium(II) chloride appears as colorless needle-like crystals, whereas chromium(III) chloride forms reddish-purple crystals. Chromium(IV) chloride exists as a gas at high temperatures.

Chromium(III) chloride, a Lewis acid, becomes more reactive in ligand substitution reactions upon the addition of zinc or a reducing agent like hydrochloric acid. The reduction to chromium(II) chloride facilitates immediate ligand replacement and electron transfer, enabling the regeneration of activated Cr(II).

Structure of Chromium Chloride

Figure 1. The complex of Chromium Chloride and Pyridine

Chromium chloride compounds are known by their oxidation states: Chromium(II) chloride (CrCl₂), chromium(III) chloride (CrCl₃), and chromium(IV) chloride (CrCl₄). The molecular weights are 122.90 for CrCl₂, 158.36 for CrCl₃, and 193.81 for CrCl₄. Anhydrous chromium(III) chloride is a purple crystal with limited water solubility.

Hydrated forms and pyridine complexes of chromium(III) chloride demonstrate its versatility in forming octahedral structures with coordination numbers of 6.

Other Information on Chromium Chloride

1. Synthesis of Chromium Chloride

Chromium(III) chloride anhydride is produced at high temperatures or by reacting dichromium trioxide with chlorine and carbon at 800°C. The hydrate form can be synthesized from hydrochloric acid and chromium, with dehydration possible using thionyl chloride. Chromium(II) chloride is obtainable by reducing chromium(III) chloride with hydrogen or reacting chromium acetate with hydrogen chloride.

2. Chromium Chloride as a Raw Material

Figure 2. Synthesis of Organochromium Compounds

Anhydrous chromium(III) chloride is crucial in organometallic chemistry for synthesizing various organochromium compounds, including diphenylchromium.

3. Reactions Using Chromium Chloride

Figure 3. Reaction Using Chromium Chloride

Reduced from chromium(III) chloride, chromium(II) chloride acts as a reducing agent in organic synthesis, capable of converting C-Cl bonds to C-H bonds and reducing aldehydes to alkenes. A common reduction involves a 2:1 molar ratio of chromium(III) chloride to lithium aluminum hydride.

What Is Calcium Chloride?

Calcium chloride is a calcium and chlorine compound, occurring naturally in limited ores and trace amounts in seawater. It appears as colorless or white crystals, highly soluble in water, and soluble in ethanol and acetone.

Uses of Calcium Chloride

1. Desiccant

Known for its excellent hygroscopicity, calcium chloride is used as a dehumidifying agent, outperforming silica gel in moisture absorption by five times. Its moisture absorption, unlike that of activated carbon or silica gel, is chemical (covalent bonding). It is also applied on road surfaces for dust control by maintaining moisture.

2. Snow Melting/Anti-freezing Agent

Calcium chloride releases heat upon reacting with moisture, making a 30% solution an effective anti-freeze and snow-melting agent that operates down to nearly -50℃. It is preferred over other agents like sodium or magnesium chloride.

3. Pharmaceuticals

It finds applications in medical treatments, including injections, infusions, and sometimes in osteoporosis therapy.

4. Food Products

As a food additive, calcium chloride adjusts the hardness and pH of beverages and serves as a coagulant in cheese and tofu production.

5. Petrochemicals

In the petrochemical industry, it enhances oil extraction efficiency by water absorption and is used for the dehydration of ethylene gas.

6. Other Uses

Calcium chloride aids in gypsum production through reactions with sulfates and fluorine removal from wastewater by forming precipitates of calcium fluoride.

Properties of Calcium Chloride

With a molecular weight of 111, specific gravity of 2.15, melting point of 772°C, and CAS number 10043-52-4, calcium chloride is notably soluble in water. Its flame reaction yields a dark orange color.

Types of Calcium Chloride

Available in hydrated forms and as a liquid, calcium chloride’s applications vary by its form, including dihydrate and hexahydrate versions, each with specific properties and uses.

1. Calcium Chloride Dihydrate (CaCl₂-2H₂O)

With a molecular weight of 147.01 and a melting point of 175.5°C, this form is water-soluble and serves as the main component of sinjalite.

2. Calcium Chloride Hexahydrate (CaCl₂-6H₂O)

Characterized by its needle-like crystals and a low melting point of 29.8°C, it is ideal for educational purposes in crystal growth demonstrations.

Other Information on Calcium Chloride

How Calcium Chloride Is Produced

Production methods include the ammonia-soda process for sodium carbonate, yielding calcium chloride as a byproduct, and direct reaction of hydrochloric acid with limestone or calcium hydroxide.

What Is Acetyl Chloride?

Figure 1. Basic Information on Acetyl Chloride

Acetyl chloride, derived from acetic acid, is known chemically as ethanoyl chloride. It produces white smoke in moist air due to its reaction with water, resulting in acetic acid and hydrogen chloride. This reactivity means it is seldom found naturally.

Available commercially, acetyl chloride can be synthesized through reactions involving acetic acid with thionyl chloride or phosphorus trichloride.

Uses of Acetyl Chloride

Acetyl chloride is pivotal in organic synthesis, particularly for introducing the acetyl group (CH₃CO-) into organic compounds. Its application in the Friedel-Crafts reaction, alongside a Lewis acid catalyst like AlCl₃, aids in synthesizing aromatic ketones. It is also used to produce acetophenone and ethyl acetate via acetylation of benzene and ethanol, respectively.

Properties of Acetyl Chloride

As a colorless, flammable liquid at room temperature, acetyl chloride has a pungent odor and can irritate the eyes and skin. It exhibits a density of 1.105 g/cm³, with melting and boiling points of -112°C and 51°C, respectively. Its solubility extends to benzene, chloroform, ether, and petroleum ether. The compound’s molecular formula is C₂H₃ClO, with a molecular weight of 78.50.

Other Information on Acetyl Chloride

1. Synthesis of Acetyl Chloride

Figure 2. Synthesis of Acetyl Chloride

Industrially, acetyl chloride is produced from acetic anhydride and hydrogen chloride, yielding acetyl chloride and acetic acid. Lab-scale synthesis may involve potassium acetate reacting with phosphoryl chloride. Discovered by Charles Gerhardt in 1852, it can also be synthesized using phosphorus trichloride, pentachloride, sulfuryl chloride, phosgene, and thionyl chloride. These methods may introduce impurities that affect reactions. Clean synthesis options include the carbonylation of methyl chloride or the reaction of acetic acid with acetonitrile and hydrogen chloride.

2. Reactions Involving Acetyl Chloride

Figure 3. Reactions Involving Acetyl Chloride

Acetyl chloride is used in acetylation reactions to produce esters from alcohols and amides from amines. Reaction with carboxylic acids forms acid anhydrides.

3. Acetylation Reaction With Acetyl Chloride Using a Base

The Schotten-Baumann reaction, which uses bases like triethylamine or sodium hydroxide to neutralize hydrogen chloride, synthesizes esters and amides from alcohols or amines with carboxylic acid chlorides. Depending on the reactivity, sodium bicarbonate or sodium carbonate may be used. Pyridine and 4-dimethylaminopyridine (DMAP) facilitate acetylation of alcohols and amines, acting as catalysts in producing acetylpyridinium salts.

What Is Sodium Bisulfite?

Sodium bisulfite is an inorganic compound, commonly found as a mixture of two forms: sodium hydrogen sulfite (NaHSO₃) and sodium bisulfite (also known as sodium pyrosulfite, Na₂S₂O₅). It is sometimes referred to as acidic sodium sulfite or anhydrous sodium bisulfite. This compound appears as a white, crystalline powder with a slight sulfur odor. It is soluble in water but almost insoluble in ethanol. Its aqueous solutions are slightly acidic.

Uses of Sodium Bisulfite

Sodium bisulfite serves multiple roles, primarily as an antiseptic and bleaching agent in the food industry. Its applications extend to leather processing, dye and intermediate purification, photography, and as a reducing and bleaching agent. In wastewater treatment, detergents, and perfumes, it plays a crucial role. Additionally, in pharmaceuticals and cosmetics, it functions as an antioxidant. Its use in cosmetics is regulated for safe concentration levels. Furthermore, sodium bisulfite reacts with formaldehyde, a chemical known to cause sensitivity and contribute to sick building syndrome, especially in moist environments.

Properties of Sodium Bisulfite

Sodium bisulfite comprises hydrogen sulfite and bisulfite ions, each forming a salt with sodium. In its solid state, it is unstable and gradually oxidizes in air to sulfate, emitting sulfurous acid gas. Commonly sold as a concentrated aqueous solution (34% or higher), it decomposes upon heating, forming sulfurous acid gas and releasing aldehydes and adducts.

Other Information About Sodium Bisulfite

1. How Sodium Bisulfite Is Produced

Production of sodium bisulfite involves refined sulfur (S) and sodium hydroxide (NaOH). The process starts with roasting sulfur to produce sulfurous acid gas, which then reacts with a sodium hydroxide solution. The resultant clear, pale yellow solution is filtered, leading to the formation of sodium bisulfite. Concentration and crystallization processes further yield sodium hydrogen sulfite crystals, which are dehydrated to form sodium bisulfite powder.

2. Safety of Sodium Bisulfite

Sodium bisulfite, while nonflammable, releases toxic sulfur dioxide gas when thermally decomposed. It reacts with acids, producing sulfurous acid gas, and intense heat when combined with oxidants. Its use as a food additive is generally safe, but high concentrations in industrial applications necessitate careful handling to prevent environmental pollution.

What Is Calcium Sulfite?

Calcium sulfite is a compound formed from calcium, often encountered as calcium sulfite 0.5 hydrate. It typically appears as a white crystalline substance or powder. This compound is insoluble in water but dissolves in sulfurous acid and dilute hydrochloric acid, releasing sulfur dioxide. It can also decompose, emitting sulfurous acid gas, and therefore requires careful handling.

Calcium sulfite can be produced by reacting calcium oxide, calcium carbonate, or calcium hydroxide with sulfur dioxide. When exposed to air, it gradually oxidizes to calcium sulfate.

Uses of Calcium Sulfite

As a reducing agent, calcium sulfite is primarily used to remove residual chlorine from tap water. Chlorine, added to tap water for disinfection, imparts a characteristic odor. Calcium sulfite effectively removes free residual chlorine, working instantaneously. It is particularly advantageous in water purifiers with high water flow rates due to its minimal reducing agent requirement and rapid reaction time compared to conventional methods like activated charcoal. Furthermore, its efficacy in removing chlorine from hot water makes it a popular choice for water-purifying shower heads.

What Is Sulfurous Acid?

Sulfurous acid, with the chemical formula H₂SO₃, is believed to exist in aqueous solutions of sulfur dioxide. It belongs to the oxoacids of sulfur, having a CAS number of 7782-99-2. Although the free acid is unstable and cannot be isolated, it is often referred to in solutions where the sulfite ion HSO₃^– predominates.

Sulfurous acid is commonly found in its aqueous form, and sulfur dioxide gas is sometimes referred to as sulfurous acid gas.

Uses of Sulfurous Acid

Sulfurous acid and sulfur dioxide serve as reducing and bleaching agents. They find applications as food additives, preservatives in dried fruits and liquors, antioxidants, and bleaching agents. Additionally, their uses extend to disinfectants in food processing, agricultural fumigants, insecticides, antiseptics, and preservatives for fruits and vegetables. They are also employed as bleaching agents in the paper, textiles, straw, gelatin, glue, and sugar industries.

Properties of Sulfurous Acid

Figure 1. Basic Information on Sulfurous Acid

Sulfurous acid, when mixed with water, creates a clear, colorless liquid with a density of 1.03 g/mL. It has a pungent odor and is miscible with water and ethanol.

Types of Sulfurous Acid

1. Aqueous Sulfurous Acid

Aqueous sulfurous acid is available as a reagent for research and development, typically used as a general analysis reagent and reducing agent. It is available in various volumes, with sulfur dioxide concentrations usually around 5% or 6%. Due to its strong odor, it should be handled in well-ventilated areas.

2. Sulfurous Acid Gas

Sulfur dioxide gas, referred to as sulfurous acid gas, is used as a bleaching and reducing agent in metal production and chemical manufacturing. It is typically stored under high pressure as a liquefied gas and requires careful handling.

Other Information on Sulfurous Acid

1. Equilibrium of Aqueous Sulfurous Acid

Figure 2. Equilibrium of Aqueous Sulfurous Acid

In aqueous solutions, sulfurous acid is believed to be in equilibrium with its ions, transitioning between hydrogen sulfurous acid ions and their dimerized structures, and further reacting with oxygen to form sulfate ions.

2. Physical Hazards of Sulfurous Acid

Sulfurous acid and sulfur dioxide can be hazardous; heating can increase pressure, posing a rupture risk. They react violently with various substances, including ammonia and chlorine, and can corrode materials upon contact with water or steam.

3. Human Health Hazards of Sulfurous Acid

Figure 3. Human Health Hazards of Sulfurous Acid

Sulfurous acid poses several health risks, including serious skin burns, eye damage, inhalation hazards, and potential organ damage with prolonged exposure. Its GHS classification includes acute toxicity, skin corrosion, and specific target organ toxicity.

4. Regulatory Information on Sulfurous Acid

Due to its hazardous nature, sulfurous acid is regulated under various safety laws. Proper handling in compliance with regulatory requirements is essential.

What Is Nitrous Oxide Gas?

Nitrous oxide gas, a type of nitrogen oxide, has the formula N₂O. It is also known as hyponitrous anhydride, laughing gas, and dinitrogen monoxide. This gas is colorless with a characteristic odor at room temperature.

Uses of Nitrous Oxide Gas

Nitrous oxide gas is widely used in medical settings for anesthesia, particularly in dentistry, surgery, and obstetrics and gynecology. Industrially, it serves as a carrier gas in semiconductor manufacturing and atomic absorption analysis and is used in leak detection, refrigeration, and inflating balloons and tires. In culinary arts, it’s used to create light, airy dishes through a method called espuma, popularized by a renowned Spanish restaurant and adopted in Japan. Additionally, due to its higher oxygen content, nitrous oxide is used in boosting internal combustion engines, such as in racing cars.

Principle of Nitrous Oxide Gas

While nonflammable and stable, nitrous oxide gas poses risks when heated to 650 °C, as it decomposes into NOx vapors, creating fire and explosion hazards. It reacts violently with certain reducing agents and flammable substances, including anhydrous sulfurous acid, amorphous boron, phosphine, ether, aluminum, hydrazine, phenyl lithium, tungsten carbide, and ammonia. It is also a strong oxidizer above 300 °C and can form explosive mixtures with substances like carbon monoxide and oil. Due to its euphoric effects when inhaled, it is now regulated as a designated drug in some jurisdictions.

Production Methods for Nitrous Oxide Gas

1. Pyrolysis Method of Ammonium Nitrate

Ammonium nitrate is decomposed in a reaction tank at about 250 °C to produce nitrous oxide gas. The crude gas, containing impurities like nitrogen, ammonia, and nitrogen dioxide, is purified by condensation, water removal, and washing with alkaline and acidic solutions.

2. Ammonia Direct Oxidation Method

Ammonia is catalytically oxidized to produce nitrous oxide gas. Despite challenges like low nitrous oxide concentration and short catalyst life, improvements in catalysts have made this method viable. The crude gas is purified by absorption into water under pressure, followed by dissipation under reduced pressure.

3. Sulfamic Acid Method

This method involves reacting sulfamic acid with nitric acid at 80-100 °C, producing nitrous oxide gas, sulfuric acid, and water.

NH₂SO₃H + HNO₃ → N₂O + H₂SO₄ + H₂O