月: 2023年1月

What Is Nitrobenzene?

Nitrobenzene is an aromatic nitro compound with the chemical formula C6H4NO2, also called nitrobenzole. It has a melting point of 5.7°C, a boiling point of 210.8°C, a specific gravity of 1.20 (at 20°C), a pale yellow color, and an almond aromatic odor. It is soluble in organic solvents and insoluble in water. It is designated as a deleterious substance under the Poisonous and Deleterious Substances Control Law.

Formation of Nitrobenzene

Nitrobenzene can be synthesized by reacting benzene with a mixed acid adjusted by concentrated sulfuric acid and concentrated nitric acid, which is called nitration. In the reaction stage, nitronium ions (NO2+) are first produced by the mixed acid as active species, which react with benzene to synthesize nitrobenzene. This reaction is accompanied by a large exothermic reaction and is one of the most dangerous chemical reactions.

Reaction of Nitrobenzene

Nitrobenzene are further nitrated by concentrated sulfuric acid and fuming nitric acid to form meta-dinitrobenzene (1,3-dinitrobenzene). Nitrobenzene are also reduced in acidic conditions to aniline. As an example of application, there is a reaction that produces quinoline from nitrobenzene, glycerin, aniline, and sulfuric acid, which is called the Skraup quinoline synthesis.

Uses of Nitrobenzene

The main uses of this substance are as a synthetic intermediate (aniline, benzidine, quinoline, azo dye) in pharmaceuticals, agrochemicals, dyes, fragrances, and rubber. Reduction in acidic and neutral conditions yields aniline, while reduction in alkaline conditions yields azoxybenzene, azobenzene, and then hydrazobenzene. It is also a raw material for gas (adam site). It is sometimes used as a polar solvent and sometimes as a mild oxidizing agent.

Effects on Living Organisms

Although not highly toxic, both liquid and vapor are toxic and can be absorbed through the skin, causing nervous system and liver damage and anemia. 17 months of occupational exposure to the substance has resulted in headache, nausea, dizziness, weakness, numbness in the legs, hyperalgesia of the limbs, cyanosis, hypotension, splenomegaly, hepatomegaly, jaundice, and other symptoms. Effects on the nerves and liver such as swelling of the spleen, liver swelling and tenderness, jaundice, and methemoglobinemia have been reported as a result of exposure to this substance.

What Is Nitroglycerin?

Nitroglycerin is an organic compound used as a powerful explosive and a medicinal agent for angina pectoris. While commonly associated with the term “nitro” in both contexts, it’s important to distinguish that nitroglycerin is a nitrate ester rather than a nitro compound.

The handling of undiluted nitroglycerin requires utmost care due to its extreme sensitivity to vibrations or friction, which can lead to accidental detonations. Nonetheless, with proper safety measures, the risk of explosion can be significantly reduced, although historical lack of safe handling practices led to frequent accidents.

Uses of Nitroglycerin

Nitroglycerin finds its primary applications in the fields of explosives and pharmaceuticals. Its explosive properties, triggered by heat, vibration, and friction, make it a key ingredient in dynamite, where it’s mixed with nitrocellulose to create nitrogel. In dynamite, the composition includes at least 6% nitroglycerin.

Medically, nitroglycerin is utilized to treat angina pectoris. Administered as a sublingual tablet, it undergoes metabolic processes to release nitrite, which then converts to nitric oxide. This process leads to the relaxation of vascular smooth muscles and dilation of blood vessels, providing relief from angina symptoms.

Properties of Nitroglycerin

This compound is characterized by its colorless or pale yellow oily appearance, poor water solubility, and good solubility in organic solvents. It melts at 14°C and decomposes at temperatures between 50-60°C. Its high sensitivity to impact and friction necessitates careful handling to prevent accidental detonation.

Strategies to reduce nitroglycerin’s sensitivity include dilution with water or acetone or its conversion into nitrogel. The compound, with the formula C₃H₅(ONO₂)₃, has a molecular weight of 227.0865g/mol and a density of 1.6g/cm³ at 15°C. Its molecular structure features tetrahedral carbon atoms and triangular nitrogen atoms.

Other Information on Nitroglycerin

1. Synthesis Method of Nitroglycerin

Discovered by Ascanio Sobrero in 1847, nitroglycerin is synthesized by esterifying glycerin with nitric acid, transforming it into a nitrate ester.

2. Storage of Nitroglycerin

To store nitroglycerin safely, it should be frozen at 8°C and is known to thaw at 14°C. The compound exhibits increased sensitivity when partially frozen, making it more prone to explosion. Repeated freeze-thaw cycles can destabilize nitroglycerin, especially in gel form, necessitating controlled temperature storage to avoid melting or freezing, especially in its dynamite form.

3. How to Use Nitroglycerin

For melting, nitroglycerin should be heated indirectly in a double boiler, ensuring that air does not become trapped around the jar’s rim and avoiding stirring to prevent detonation risks. Even when in gel form, care must be taken to avoid introducing air bubbles during processing, as this can lead to explosive outcomes.

4. Compounds Related to Nitroglycerin

Nitroglycerin, a nitrate ester of glycerin, shares its origins with glycerin—a clear, colorless liquid known for its sweet taste. Glycerin’s versatility sees it used in various applications, including as a preservative, sweetener, humectant, stabilizer in food, and as an ingredient in cosmetics and medicines.

What Is Lithium Niobate?

Lithium niobate, a compound of niobium oxide and lithium oxide, is a synthetic material not found naturally. At room temperature, it is an odorless substance and insoluble in water. Lithium niobate crystals are grown using the Choklarsky process and are notable for their piezoelectric and nonlinear optical properties.

Uses of Lithium Niobate

Lithium niobate exhibits piezoelectricity, generating surface electrodes in response to applied pressure, and nonlinear optical effects, reacting independently of light intensity with strong light. These properties make it valuable in electronics, particularly in the manufacturing of cellular phones, electrical modulators, and resonators. Along with lithium tantalate, lithium niobate is commonly used in Surface Acoustic Wave (SAW) devices, such as SAW filters in telecommunications equipment, to remove noise from voice data.

What Is Naphthalene?

Naphthalene is an aromatic hydrocarbon composed of carbon and hydrogen. Its chemical formula is C₁₀H₈. Produced by refining coal tar, it appears as white or colorless, shiny, monoclinic, scaly crystals. As a prevalent aromatic hydrocarbon, naphthalene is utilized in synthesizing phthalate esters, aniline, and naphthalene oxide, serving as an essential material for various synthetic dyes and resins.

Uses of Naphthalene

Primarily, naphthalene is employed in producing insect repellents, dyes, pharmaceuticals, agrochemicals, and lubricants. Its derivatives enhance the durability and vividness of dyes for cotton and wool fabrics and contribute to pharmaceuticals by testing for phenols in blood. Despite its historical use as a clothing insect repellent, modern alternatives like paradichlorobenzene are becoming more common. However, naphthalene still finds applications in agriculture, wood preservation, and as a precursor for organic pigments and specific hydrocarbons.

Properties of Naphthalene

Naphthalene, a non-polar molecule, exhibits solubility in organic solvents but not in water. Its intermolecular forces increase with molecular weight, leading to characteristics like non-volatility and high melting points in polycyclic aromatic hydrocarbons. Naphthalene’s reactivity towards oxygen necessitates careful storage to avoid oxidative degradation. It is sensitive to strong oxidizers, which can lead to hazardous reactions.

Structure of Naphthalene

The structure of naphthalene consists of two covalently bonded benzene rings, forming a planar polycyclic aromatic hydrocarbon. It features monosubstituted forms with structural isomers identified as α-position and β-position based on the location of the substituent.

Other Properties of Naphthalene

Safety Information on Naphthalene

Naphthalene is regulated under various safety laws due to its flammability and potential health hazards. Handling naphthalene requires appropriate protective measures to prevent skin and eye irritation. Its mixtures with oil or organic solvents are particularly flammable, emphasizing the need for caution to prevent fires.

What Is a Tall Oil?

Tall oil is a mixture of fatty acids, resin acids, and unsaponifiable substances produced as a byproduct of the pulp manufacturing process.

It appears as a dark brown viscous liquid. During pulp production, wood chips undergo processing and evaporation with an alkaline solution, resulting in the extraction of pulp (fiber). The concentrated liquid derived from this process, known as black liquor, yields tall oil.

The unrefined tall oil obtained from black liquor is termed crude tall oil, which can be further separated and refined into tall rosin and tall fatty acids through distillation in a distillation column. These refined products find industrial applications.

Uses of Tall Oils

Tall oil serves as an inexpensive fatty acid raw material widely utilized in various industries, notably in the manufacture of greases, industrial soaps, emulsifiers, paints, and printing inks. Tall oil fatty acids find application as paint resins, such as alkyd resins, and in the production of azelaic acid, oleic acid, and linoleic acid.

Additionally, it functions as a surfactant in fuel additives and detergents. Tall oil rosin serves as an emulsifier for synthetic rubber, various anti-slip agents, and paints for road surface markings.

It is also extensively employed as an adhesive agent in tapes, hot melt adhesives, and recycled paper processing agents, among other applications.

Properties of Tall Oils

Derived from pine wood, tall oil exhibits less susceptibility to seasonal changes compared to other plant-derived alternatives. Tall oil fatty acids predominantly comprise oleic acid and linoleic acid, with negligible amounts of stearic acid and palmitic acid.

It contains no polyunsaturated fatty acids beyond linolenic acid and minimal quantities of saturated fatty acids. Tall oil rosin primarily consists of resin acids, including abietic acid, dehydroabietic acid, neoabietic acid, parastatic acid, pimaric acid, and isopimaric acid.

Additional components present in tall oil include sesquiterpenes, terpene alcohols, phenolic substances, and low molecular weight fatty acids, while pitch comprises esters of fatty acids and resin acids, along with their polymerization products, oxides, sterols, and ligninous substances.

Types of Tall Oils

Tall oil is primarily produced in paper mills located in the United States, Canada, Russia, and China. As it is derived from wood, its composition ratio varies based on the pine species utilized.

In Japan, tall oil is mainly imported from North America and further refined into tall rosin. Crude tall oil serves as the raw material for tall oil fatty acids, tall oil fats (tall rosin), and other substances, which are separated into several types through distillation and refining processes for industrial applications.

Other Information on Tall Oils

1. Origin of Tall Oil

The term “tall” originates from the Swedish word for pine (tall). The composition of tall oil varies depending on the pine species used, such as slash pine, European red pine, and babyshoe pine.

2. Tall Oil Production Process

In kraft pulp mills, tall oil is produced as a byproduct through the following processes:

1. Wood chips (pulpwood) are boiled and dissolved with chemicals like sodium hydroxide (caustic soda) (evaporation).
2. Pulp (wood fiber) is separated from the resulting white liquid (a mixture of lignin, resin, and chemicals).
3. The white liquor is concentrated to obtain black liquor.
4. Sodium soap of the resin acids and fatty acids present in pine, dissolved in black liquor, is salted out during concentration, forming creamy suspended solids (skimmings).
5. The skimmings are decomposed with acid to liberate crude tall oil.

The crude tall oil obtained is then distilled in a distillation column, yielding four fractions: tall oil fatty acids, tall oil fat (tall rosin), tall oil primary distillate, and pitch, which can be reprocessed into various bio-chemicals.

What Is Toluene?

Toluene is a clear, colorless liquid belonging to the aromatic hydrocarbon family with a distinctive odor. It is extremely insoluble in water but miscible with alcohols and other organic solvents. Due to its ability to dissolve organic substances and polymers, toluene is used as a solvent in synthetic experiments, paints, and printing inks. However, it is highly flammable and toxic and requires safety measures such as avoiding ignition sources and ensuring ventilation.

Uses of Toluene

Toluene is a versatile solvent used in synthetic reactions, paint formulations, and printing inks. It is also a raw material in petrochemistry for producing aromatic compounds like benzoic acid, trinitrotoluene, benzaldehyde, benzene, and xylene.

Chemical Reactions of Toluene

Toluene can undergo various chemical reactions, including nitration with nitric and sulfuric acids, oxidation to benzoic acid, and conversion to methylcyclohexane by hydrogenation. These reactions are important in large-scale petrochemical processes, where the key considerations are catalyst longevity and cost reduction.

Other Information on Toluene

Safety of Toluene

As a toxic and flammable compound, toluene requires careful handling. It has a low flash point, making it easily ignitable at room temperature. Static electricity, particularly in nonconductive or ungrounded containers, can pose a significant ignition risk. Precautions include avoiding mixing with strong oxidizers or chloroform, flowing nitrogen gas to cut off oxygen, and ensuring proper training and equipment for handling. Toluene’s high volatility and toxicity to reproduction and the central nervous system necessitate adequate ventilation to prevent poisoning, especially in poorly ventilated areas.

What Is Toluidine?

Toluidine is an aromatic compound featuring an amino group and a methyl group attached to the benzene ring.

It belongs to the class of aniline derivatives and aromatic amines, with three isomers: o-toluidine, m-toluidine, and p-toluidine, differing in the positional relationship between the amino and methyl groups. Among these, o-toluidine and m-toluidine are liquids, while p-toluidine is a solid at room temperature and pressure.

Uses of Toluidine

Toluidine serves primarily as an intermediate in chemical synthesis and finds applications across various industrial sectors.

For instance, o-toluidine is employed as a raw material for toluidine blue dye production. Toluidine blue, derived from o-toluidine, thiazine, and phenothiazine, is a blue basic dye that stains negatively charged materials and is particularly useful for biomaterial and plant staining.

Furthermore, toluidine serves as a precursor in pharmaceutical synthesis and rubber vulcanization.

Properties of Toluidine

Toluidine, an aniline derivative, and aromatic amine, exists in three isomers: o-toluidine, m-toluidine, and p-toluidine. Its chemical formula is C₇H₉N, with a molecular weight of 107.15 g/mol. While slightly soluble in water, it readily dissolves in organic solvents such as ethanol, ether, and acetone. Pure toluidine appears as a colorless or slightly yellow crystal or liquid but may turn brown upon oxidation in the air.

Each isomer exhibits distinct melting and boiling points:

• o-Toluidine: Melting point -23°C, Boiling point 200°C
• m-Toluidine: Melting point -30°C, Boiling point 203°C
• p-Toluidine: Melting point 43°C, Boiling point 200°C

Notably, o-toluidine is considered carcinogenic and mutagenic, warranting careful handling.

Structure of Toluidine

Toluidine, a derivative of aniline (C₆H₅NH₂), represents an aromatic amine with the chemical formula C₆H₄(CH₃)NH₂.

Existing as three isomers, o-toluidine, m-toluidine, and p-toluidine, these compounds feature methyl groups attached at different positions on the benzene ring. Consequently, they exhibit distinct physical and chemical properties based on the relative positions of the methyl and amino groups.

All toluidine isomers share the characteristics of aromatic amines and can react with acids to form salts and with oxidizing and reducing agents.

Other Information on Toluidine

1. Toluidine Production Methods

Toluidine is primarily produced through the following methods:

• Reduction of Nitrotoluene: Toluidine is commonly synthesized via the reduction of nitrotoluene, achieved through chemical reduction using iron or zinc powder and acid or by catalytic hydrogenation reduction.
• Synthesis from Aniline: An alternative route involves synthesizing toluidine from aniline using the Friedel-Crafts condensation reaction. This process requires a catalyst such as aluminum chloride (AlCl₃) or iron (III) chloride (FeCl₃) and an appropriate alkylating agent like methyl chloride (CH₃Cl) or ethyl chloride (C₂H₅Cl).

2. Regulation of Toluidine

o-toluidine, m-toluidine, and p-toluidine are all regulated under various regulatory laws as hazardous substances, poisonous and deleterious substances, and inflammable liquids.

What Is Trichloroethylene?

Trichloroethylene is an organic compound where the three hydrogen atoms in ethylene are substituted by chlorine atoms.

Also known as trilene or trichlene, it appears as a clear, colorless liquid at room temperature.

Due to its toxicity,  the International Agency for Research on Cancer (IARC) classifies its carcinogenicity as Group 1 (carcinogenic to humans).

Uses of Trichloroethylene

Trichloroethylene finds primary usage in degreasing and cleaning metal and electronic parts, owing to its ability to dissolve oils, greases, and lubricants. It serves as a solvent in adhesives to dissolve rubber and resins, and in the industrial manufacture of dyes and paints.

Furthermore, it acts as a raw material for synthesizing CFC substitutes and is involved in CFC gas production.

Trichloroethylene is utilized in dry cleaning to remove oil from clothing, wool, and leather items unsuitable for water washing. Additionally, it serves as a standard concentration solution for comparison in water quality measurements, albeit in limited quantities.

Properties of Trichloroethylene

Trichloroethylene has a boiling point of 86.7°C, a melting point of -86.4°C, and an ignition point of 420°C. It is nonflammable and volatile at room temperature, emitting a sweet odor reminiscent of chloroform.

It is highly soluble in various organic solvents such as ethanol, diethyl ether, and chloroform. However, it exhibits instability in the presence of metals, especially over prolonged periods and at elevated temperatures. Commercially available trichloroethylene often includes additives to address this issue.

Structure of Trichloroethylene

Trichloroethylene is an organochlorine compound in which three hydrogen atoms of ethylene are substituted by chlorine atoms. Organochlorine compounds entail chlorine bonded to a carbon-containing compound.

Its chemical formula is C₂HCl₃, with a density of 1.46g/cm³ at 20°C.

Other Information on Trichloroethylene

1. Synthesis of Trichloroethylene Using Acetylene

Before the early 1970s, trichloroethylene was synthesized from acetylene through a two-step reaction. Chlorine reacts with acetylene at 90°C, with an iron (III) chloride catalyst yielding 1,1,2,2-tetrachloroethane.

Subsequently, trichloroethylene can be synthesized from 1,1,2,2-tetrachloroethane by reacting it with aqueous calcium hydroxide. The former is synthesized by gas-phase heating of 1,1,2,2-tetrachloroethane to 300-500°C using catalysts like calcium chloride or barium chloride.

2. Trichloroethylene Synthesis Using Ethylene

Presently, most trichloroethylene is produced from ethylene. The chlorination of ethylene with iron (III) chloride as a catalyst yields 1,2-dichloroethane.

Heating chlorine with 1,2-dichloroethane to around 400°C results in trichloroethylene. Catalysts such as a mixture of aluminum chloride and potassium chloride or porous carbon can be employed for the chlorination of 1,2-dichloroethane. Depending on chlorine concentration, tetrachloroethylene may be a byproduct, separable by distillation.

3. Trichloroethylene Hazards

Inhalation or direct contact with trichloroethylene vapor can induce poisoning symptoms like headache, dizziness, and vomiting. It poses risks of liver and kidney damage.

Highly toxic to humans, trichloroethylene, when released into the environment, is insoluble in water, leading to soil and groundwater contamination issues. Consequently, strict regulations govern its handling.

What Is Trichloroethane?

Trichloroethane is an organic halogen compound with the molecular formula C₂H₃Cl₃.

It is classified into two types, 1,1,1-trichloroethane, and 1,1,2-trichloroethane, based on the position of the chlorine atom. 1,1,1-trichloroethane, also known as chlorotene or methyl chloroform, exists as a colorless liquid at room temperature.

It irritates human skin and eyes and is designated as a hazardous substance to be labeled or notified by name under various laws.

Uses of Trichloroethane

1,1,1-trichloroethane, due to its ability to dissolve various organic compounds, was extensively used as an organic solvent for cleaning electronic components and as a paint solvent. However, its use has been largely discontinued worldwide since its classification as an ozone-depleting substance under the Montreal Protocol.

Properties of Trichloroethane

1,1,1-trichloroethane has a melting point of -30°C and a boiling point of 74°C. It is volatile and possesses excellent cleaning capabilities.

While generally classified as a nonpolar solvent, it exhibits a slight degree of polarity due to the presence of three chlorine atoms with high electronegativity, which are biased to one side of the molecule.

Structure of Trichloroethane

1,1,1-trichloroethane and 1,1,2-trichloroethane are structurally related isomers, both featuring three of the four hydrogen atoms attached to the carbon atom of ethane replaced by a chlorine atom.

The molecular formula of 1,1,1-trichloroethane is CH₃CCl₃, with a molecular weight of 133.40 and a density of 1.34g/cm³.

Other Information on Trichloroethane

1. Synthesis of 1,1,1-Trichloroethane

1,1,1-trichloroethane can be industrially synthesized in two steps from the raw material chloroethylene. First, chloroethylene reacts with hydrogen chloride at 20-50°C, using catalysts like aluminum chloride, iron (III) chloride, or zinc chloride, to produce 1,1-dichloroethane. Subsequently, 1,1-dichloroethane reacts with chlorine under UV irradiation to yield 1,1,1-trichloroethane.

The yield is approximately 80-90%, with the generated hydrogen chloride being reusable. Although the main byproduct is the structural isomer 1,1,2-trichloroethane, it can be separated by distillation.

A small amount of 1,1,1-trichloroethane can also be obtained from the reaction of 1,1-dichloroethene (vinylidene chloride) with hydrogen chloride using iron (III) chloride as a catalyst.

2. Presence of 1,1,1-Trichloroethane in the Atmosphere

The Montreal Protocol identified 1,1,1-trichloroethane as one of the compounds contributing to ozone layer depletion, leading to its global prohibition starting in 1996. Consequently, its atmospheric concentration is rapidly declining due to its relatively short lifespan of 5 years.

3. Characteristics of 1,1,2-Trichloroethane

Also known as trichloroethane, 1,1,2-trichloroethane has a melting point of -6°C and a boiling point of 114°C. With a molecular weight of 133.40 and a density of 1.44g/cm³, it appears as a colorless liquid at room temperature, emitting a sweet aroma. Its specific formula is C₂H₃Cl₃.

It exhibits a central nervous system depressant effect, with inhalation leading to symptoms such as headache and nausea. Unlike 1,1,1-trichloroethane, 1,1,2-trichloroethane is not designated as an ozone-depleting substance. Therefore, it continues to be utilized as an organic solvent and serves as a synthetic intermediate of 1,1-dichloroethane.