月: 2023年1月

What Is Molybdic Acid?

Molybdic acid is an odorless white or light yellow powder and inorganic compound.

Uses of Molybdic Acid

Molybdic acid serves as a passive corrosion inhibitor for carbon steel in buildings and piping and finds use in pharmaceuticals, pigments, and ceramics glazes.

It also functions as a heterogeneous catalyst in various oxidation processes. Additionally, molybdic acid and its salts are components of Froehde reagent for alkaloid detection, with alkaloids being nitrogen-containing organic compounds typically of a basic nature.

Properties of Molybdic Acid

Molybdic acid melts at 300°C and forms an antimagnetic solid. It dissolves in alkaline solutions and ammonia water but is nearly insoluble in water, ethanol, and acetone.

Its chemical formula is H₂MoO₄, with a molecular weight of 161.95 and a CAS number of 7782-91-4. The monohydrate (MoO₃・H₂O) and dihydrate (MoO₃・2H₂O) forms are well-documented.

Structure of Molybdic Acid

Molybdic acid solids are coordination polymers, with the monohydrate composed of octahedrally coordinated MoO₃・H₂O units sharing four vertices. The dihydrate features additional water molecules intercalated between these layers, forming a continuous structure of ligands and metal ions.

In acidic solutions, molybdic acid appears as a complex, MoO₃(H₂O)₃, with each molybdenum atom surrounded by three aqua and three oxo ligands in an octahedral structure.

Molybdic acid salts, or molybdates, are produced by neutralizing molybdic acid with a base.

Other Information on Molybdic Acid

1. Related Compounds

Molybdates contain molybdenum(VI) oxoanions. Molybdenum forms various oxoanions, existing solely in a solid state. Its behavior differs from other group 6 elements, with chromium oxoanions being tetrahedral, while tungsten, like molybdic acid, forms various tungstates with coordination number 6.

2. Examples of Molybdic Acid Ions

The MoO₄^2- ion, found in Na₂MoO₄ and CaMoO₄, has a coordination number of 4, forming a tetrahedral structure. Mo₂O₇^2- ions, present in certain tetrabutylammonium salts, share a corner, creating a dual-tetrahedral shape.

Other ions include Mo₃O₁₀^2-, Mo₄O₁₃^2-, Mo₅O₁₆^2-, Mo₆O₁₉^2-, Mo₇O₂₄^6-, and Mo₈O₂₆^4-.

What Is Methanesulfonic Acid?

Methanesulfonic acid (CH₃SO₃H), also known as mesylic acid or MsOH, represents the simplest form of alkane sulfonic acids. This colorless, odorless, and strong organic acid stands out for its ease of handling and resistance to oxidation.

It dissolves readily in water, alcohol, and ether, while remaining insoluble in alkanes, benzene, and toluene. Notably, it exerts a strong corrosive impact on ferrous metals, copper, and lead.

Valued in the metal plating industry, methanesulfonic acid is chosen for its absence of hydrolysis reactions, capability to support high metal concentrations, and stability across a broad pH spectrum.

Uses of Methanesulfonic Acid

As a versatile organic acid, methanesulfonic acid serves a wide array of sectors, including pharmaceuticals, chemical synthesis, biofuel production, industrial cleaning, and metal surface processing in electronics manufacturing. Its biodegradability, non-oxidizing nature, and lack of color and odor render it an environmentally friendly choice over traditional acids like sulfuric, phosphoric, and acetic acids.

It’s particularly favored as a phosphoric acid alternative in cleaning agents due to its lower environmental impact. Beyond these applications, methanesulfonic acid acts as a reducing agent in dyes and a water-repellent for textiles, showcasing its broad utility.

The esters derived from methanesulfonic acid, known as mesylates, play critical roles as alkylation reagents or leaving groups in chemical reactions.

Properties of Methanesulfonic Acid

This acid is a colorless, oily liquid characterized by a pungent smell. It is highly soluble in water, enabling the creation of concentrated solutions. Its compatibility with various organic solvents further broadens its industrial applicability.

Thermal stability and resistance to decomposition under heat make methanesulfonic acid a reliable proton source for acid-catalyzed reactions and dehydration processes.

These characteristics underpin its widespread use in organic synthesis and materials science, where its low oxidizing power facilitates selective reactions with functionally sensitive compounds.

Structure of Methanesulfonic Acid

With the molecular formula CH₃SO₃H, methanesulfonic acid features a sulfonic acid group attached to methane. It boasts a molecular weight of 96.1, a density of 1.4812 g/cm³, and operates within a melting point of 18°C and a boiling point of 167°C. Its CAS number is 75-75-2.

Other Information on Methanesulfonic Acid

Production Methods

Industrial synthesis of methanesulfonic acid commonly employs the oxidation of dimethyl sulfide, among other techniques.

1. Oxidation of Dimethyl Sulfide: Utilizing strong oxidants like potassium permanganate or nitric acid to oxidize dimethyl sulfide yields methanesulfonic acid.

2. Sulfonation of Methane: Methane reacts with sulfur trioxide under specific conditions, although this method is less frequently used due to its demanding requirements.

A catalyzed reaction between sulfuric acid and methane at high temperatures also produces methanesulfonic acid, demonstrating the acid’s diverse synthesis routes.

3. Reaction with Chloromethane: Chloromethane’s reaction with concentrated sulfuric acid under controlled conditions further illustrates the acid’s versatile production methods, resulting in methanesulfonic acid and hydrogen chloride.

What Is Methane Gas?

Methane (CH₄) is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. Known also as methyl alcohol, wood spirit, or carbinol, it’s primarily sourced from natural gas and serves as a major component of city gas. Despite its non-toxic nature, methane’s high purity can lead to oxygen deficiency when inhaled in large quantities.

Uses of Methane Gas

Widely utilized as a fuel source, methane is a key component of liquefied natural gas and biogas, derived from food waste and livestock manure. It’s instrumental in the synthesis of chemicals like methanol, formaldehyde, and formic acid, and plays a role in energy applications, such as gasoline additives and biodiesel fuel production.

Properties of Methane Gas

Methane is a colorless, odorless gas at room temperature, with a melting point of -182.5°C and a boiling point of -161.6°C. It’s lighter than air, highly flammable, and capable of forming explosive mixtures with air. Methane’s simple molecular structure and tetrahedral shape make it a fundamental compound in organic chemistry.

Other Information on Methane Gas

1. Methane Synthesis Method

Industrially, methane is produced from hydrogen and carbon monoxide or by decarbonating acetates. Naturally, it’s generated through anaerobic fermentation by methanogens in environments like wetlands.

2. Methane Reaction

Methane undergoes halogenation in the presence of light and combusts completely to form carbon dioxide and water, releasing significant heat. Incomplete combustion yields carbon monoxide and water.

3. Substituents Related to Methane

Methane derivatives include methyl (CH₃-), methylene (-CH₂-), and methine (-CH<) groups, each reflecting a variation in hydrogen atom removal and bonding structure.

4. Compounds Related to Methane

Key industrial chemicals derived from methane include methanol, formaldehyde, formic acid, and hydrogen cyanide, showcasing methane’s importance as a chemical precursor.

What Is Methanol?

Methanol, also known as methyl alcohol, wood spirit, or carbinol, is the simplest form of alcohol. It’s produced primarily from natural gas or coal gas through sophisticated processes involving high temperatures and pressures. As a Class 4 hazardous alcohol with the lowest flash point among alcohols, methanol demands careful handling.

Uses of Methanol

As a fundamental chemical raw material, methanol is crucial for producing acetic acid, formaldehyde, phenolic resins, and adhesives, and serves as a solvent in numerous chemical reactions. Its role in energy sectors, such as in gasoline additives, biodiesel fuel, and as a hydrogen source for fuel cells, is increasingly significant.

Properties of Methanol

Clear, colorless, and with a pungent odor, methanol melts at -97°C and boils at 64.7°C. Its solubility spans across water, ethanol, benzene, and ether. Highly flammable, methanol’s vapor can lead to explosive reactions, and its light blue flames are nearly invisible in daylight. Methanol poisoning, potentially fatal, can result from ingestion, inhalation, or skin contact, with symptoms including blindness.

Other Information on Methanol

1. Methanol Manufacturing Process

Methanol is typically synthesized from natural gas, using a reaction between carbon monoxide and hydrogen in the presence of a copper oxide-zinc oxide/alumina catalyst. Alternative methods include wood distillation, bacterial fermentation, and as a byproduct in the wine fermentation process.

2. Reaction of Methanol

Methanol combustion produces carbon dioxide and water, while its oxidation on heated copper yields formaldehyde. Toxic to humans, methanol’s metabolism generates formic acid, causing potential blindness and metabolic acidosis. Methanol reacts with sodium to produce sodium methoxide and hydrogen.

3. Fuel Reforming With Methanol

Heated methanol generates syngas, enhancing fuel thermal efficiency due to its endothermic combustion reaction. Methanol is also explored as a fuel for hydrogen fuel cells, promising higher energy efficiency than direct methanol fuel cells, albeit with challenges related to carbon monoxide poisoning of platinum-based cells.

What Is Methyl Methacrylate?

Methyl methacrylate (MMA), also known as acrylic monomer, is an unsaturated fatty acid ester. It is soluble in ethanol and acetone and has limited solubility in water.

MMA is a colorless, highly flammable liquid and vapor with a characteristic odor. In work environments, precautions such as preventing sparks and measures against electrostatic discharge (e.g., grounding) are necessary to ensure safety.

Exposure to MMA can cause allergic reactions, asthma, and breathing difficulties. It also has the potential to affect the nervous system, leading to symptoms such as drowsiness and dizziness.

Acrylic resin derived from methyl methacrylate is known for its exceptional transparency. Polymethyl methacrylate resin (PMMA), also called acrylic glass, is used for applications like large aquariums due to its clarity.

Uses of Methyl Methacrylate

Methyl methacrylate is primarily used in the production of acrylic sheets and pressed molding resins. The polymers and copolymers formed are called methacrylic resins, utilized as raw materials for coating resins, resin modifiers, paints, paper coatings, adhesives, fiber processing materials, dental fillings, surgical cements, synthetic fingernails, and prosthetic devices.

Methacrylic resins are valued for their transparency, weather resistance, and recyclability, making them environmentally friendly. These properties have led to expanding applications in the IT and automotive sectors.

Recently, MMA has been utilized in 3D printing, offering the ability to create hard and precise moldings. This has proven particularly beneficial in the medical field for preoperative examinations, where it aids in confirming morphology and planning surgical procedures. However, due to its hardness, cutting the material post-shaping can be challenging.

What Is Methacrylic Acid?

Methacrylic acid, known as alpha-methylacrylic acid or 2-methylpropenoic acid, is an unsaturated carboxylic acid and a clear, colorless liquid with a pungent odor. It plays a critical role in the chemical industry, particularly in the production of polymers and resins.

Uses of Methacrylic Acid

As a versatile synthetic material, methacrylic acid is foundational in creating water-soluble polymers, copolymers with vinyl compounds, and ion exchange resins. Its ester, methyl methacrylate, is vital for manufacturing acrylic resins used as organic glass in various applications, including aircraft windows, automotive glass, lighting fixtures, and contact lenses. Additionally, methacrylic acid finds use in dental materials, paints, paper processing, fiber treatments, adhesives, and electrical insulators.

Properties of Methacrylic Acid

With the formula CH₂=C(CH₃)COOH, methacrylic acid features a melting point of 15°C, a boiling point of 159°C, and a specific gravity of 1.015. It exhibits strong acidity and is prone to polymerization. To prevent unwanted polymerization, hydroquinone is often added as a stabilizer. Methacrylic acid enhances the adhesion, stability, and durability of acrylic resins against various environmental factors.

Production Methods of Methacrylic Acid

Methacrylic acid is produced industrially through the ACH method and the isobutylene method. The ACH method involves the conversion of acetone cyanohydrin into methacrylic acid via a series of chemical reactions, utilizing hazardous materials like hydrogen cyanide. The isobutylene method, preferred in Japan, involves the direct oxidation of isobutylene using a molybdenum-based catalyst. Recent developments also include a process starting from ethylene to synthesize methacrylic acid through propionic acid.

Both production methods highlight the chemical industry’s efforts to optimize efficiency and safety in producing this essential compound.

What Is Sodium Polystyrene Sulfonate?

Sodium polystyrene sulfonate is a cation-exchange resin used primarily to treat hyperkalemia by exchanging sodium ions for potassium ions in the body. This yellowish-brown powder is odorless and tasteless, and it is virtually insoluble in water, ethanol, acetone, and diethyl ether.

Uses of Sodium Polystyrene Sulfonate

This resin is indicated for hyperkalemia associated with acute and chronic renal failure. It can be administered orally or rectally, not intravenously as previously mentioned. The oral dose is typically 15 to 30 g, mixed with 20 to 100 mL of water or syrup (without sorbitol), administered one to four times a day. The rectal administration involves a similar dose suspended in a small volume of water or 2% methylcellulose solution, used particularly when oral administration is not feasible.

Properties of Sodium Polystyrene Sulfonate

As a cation-exchange resin, sodium polystyrene sulfonate operates by binding potassium ions in the colon, facilitating their removal from the body through feces. This action helps reduce high potassium levels in the blood. However, it’s associated with potential side effects such as heart failure (due to increased serum sodium), gastrointestinal complications like perforation, ulcers, and necrosis (particularly with sorbitol use), and more common side effects including edema, hypocalcemia, and gastrointestinal discomfort.

Other Information on Sodium Polystyrene Sulfonate

1. Precautions for Concomitant Use

Caution is advised when used with digitalis preparations due to the risk of digitalis toxicity from lowered serum potassium levels. Antacids or laxatives containing aluminum, magnesium, or calcium, and thyroid hormones can interfere with the action of sodium polystyrene sulfonate, reducing its effectiveness or affecting thyroid hormone absorption, respectively.

2. Precautions for Use

Monitoring of serum potassium and sodium levels is essential during treatment. The risk of gastrointestinal complications underscores the importance of avoiding sorbitol-containing solutions and addressing constipation proactively. Special consideration is required when administering to pregnant or nursing women, and elderly patients may need dose adjustments due to potential physiological function impairment.

3. Difference From Calcium Polystyrene Sulfonate

While both sodium and calcium polystyrene sulfonates treat hyperkalemia, sodium variants offer a higher potassium exchange capacity, making them more effective in reducing serum potassium levels. However, calcium polystyrene sulfonate may be preferred in patients with sodium retention issues, despite its potential side effects like constipation and the risk of hypercalcemia-related complications.