月: 2023年1月

What Is Pentane Gas?

Pentane gas, an alkane with five carbon atoms, exists in three structural isomers: n-pentane, isopentane, and neopentane. Typically, the term “pentane” refers to n-pentane, the linear-chain form. It is a nonpolar compound, insoluble in water but miscible with many organic solvents like ethers and alcohols.

Classified as a Class 4 hazardous substance, pentane gas is highly volatile and flammable, even at room temperature. Therefore, handling pentane gas requires precautions such as eliminating ignition sources, preventing leakage, and ensuring adequate ventilation.

Pentane Gas Data

• CAS No.: 109-66-0
• Molecular Weight: 72.15
• Boiling Point: 36.1°C
• Melting Point: -129.7°C

Source: American Chemical Society

Uses of Pentane Gas

Pentane gas is utilized in adhesives, printing inks, organic synthesis experiments, and as an extraction solvent due to its high volatility. It’s also used as an anesthetic and in binary power generation for geothermal power plants. Additionally, n-pentane is a reference material in gas chromatography (GC).

Pentane Gas Safety and Regulations

Pentane gas, with a flash point of -49°C, is an extremely flammable compound, requiring the elimination of ignition sources during use. Though it has low acute toxicity, it can act as an anesthetic and irritant to the respiratory tract. Precautions include preventing leakage and ensuring proper ventilation. Pentane gas handling also requires adherence to OHSA regulations for risk assessment.

What Is Benzophenone?

Benzophenone, a white or almost white crystalline powder, is notable for its sweet aroma. As a key aromatic ketone compound, it serves as an essential building block in organic chemistry, often referred to as diphenyl ketone.

Properties of Benzophenone

With a melting point of 48~50°C and a boiling point of 305.4°C, benzophenone exhibits significant thermal stability. Its flash point is 143°C, and it has a density of 1.11 g/cm³. Soluble in acetone and ethanol, it remains virtually insoluble in water. Structurally, it comprises two benzene rings linked by a carbonyl group, known as Ph₂CO, with a molecular weight of 182.22 and CAS number 119-61-9.

Uses of Benzophenone

1. Photoinitiator

Its ability to absorb ultraviolet light makes it an effective photoinitiator in polymerization processes.

2. UV Absorber

Benzophenone-based UV absorbers protect plastics and paints from UV damage by converting UV light into less harmful forms of energy.

3. Preparation of Dehydrated Solvents

It is utilized alongside sodium metal to dehydrate solvents, with the blue color of benzophenone ketyl serving as an indicator for the dehydration process completion.

4. Photoaffinity Probe

In chemical biology, benzophenone is attached to small molecules to form covalent bonds with interacting proteins upon UV irradiation, aiding in the identification of protein interactions.

5. Other Uses

Derivatives of benzophenone find use as sunscreen ingredients, in organic synthesis, and as intermediates for pharmaceuticals.

Other Information on Benzophenone

1. Production Methods

Commercially, benzophenone is produced via the copper-catalyzed oxidation of diphenylmethane. Laboratory synthesis can involve hydrolysis of dichlorodiphenylmethane or the Friedel-Crafts reaction of benzoyl chloride with benzene.

2. Regulatory Information

Benzophenone is recognized as a hazardous substance under various laws, requiring careful management and handling according to various safety regulations.

3. Handling and Storage Precautions

Precautions include storing in a cool, dark place, using protective gear, and adhering to safe handling practices to prevent dust dispersion and avoid skin or eye contact.

What Is Benzonitrile?

Benzonitrile, an aromatic cyanide with the formula C₆H₅CN, was identified by Hermann von Fehling in 1844 during the decomposition of ammonium benzoate. This discovery led to the term “nitrile” for similar compounds. Classified under various regulations as a hazardous substance, a flammable liquid, and a deleterious substance, it requires careful handling.

Uses of Benzonitrile

As a versatile chemical, benzonitrile serves as a precursor to benzoic acid, benzylamine, and triazine rings through various reactions. Its applications span from plastics manufacturing to pharmaceutical and agricultural intermediates, solvents for antioxidants, plating solutions, dye construction, and epoxy resin curing agents.

Properties of Benzonitrile

This colorless liquid features an almond-like scent, a melting point of -13°C, and boils between 188-191°C. It’s flammable, with a flash point of 75°C and an ignition point of 550°C, soluble in alcohols and ethers, yet only 1% soluble in water at 100°C.

Structure of Benzonitrile

Known as phenyl cyanide, its structure includes a benzene ring with a cyano group substituting one hydrogen atom, abbreviated as PhCN. It has a molar mass of 103.04 g/mol and a density of 1.0 g/ml.

Other Information on Benzonitrile

1. Synthetic Methods

Benzonitrile is produced industrially by the ammoxidation of toluene and can be synthesized in the lab through dehydration of benzamide or benzaldehyde oxime. It’s also obtained via Rosenmund-von Braun synthesis or by diazotizing aniline in the Sandmeyer reaction.

2. Benzonitrile Reaction

Hydrolysis converts benzonitrile to benzoic acid, while reactions with amines yield N-substituted benzamides. It forms complexes with late transition metals, such as bis(benzonitrile)palladium dichloride, a yellowish-brown solid used in organic synthesis, showcasing its role as a convenient synthetic intermediate.

What Is Benzene?

Benzene, an aromatic hydrocarbon, is recognized for its simple chemical structure. This colorless liquid, known for its sweet aroma, plays a fundamental role in petrochemistry and is found in crude oil. Its vapors are toxic, affecting hematopoietic function, and hence, it’s considered a hazardous air pollutant. Recent regulations have reduced benzene content in gasoline to less than 1% from approximately 5%.

Uses of Benzene

Benzene serves as a precursor to various aromatic compounds, finding applications in dyes, synthetic rubbers, detergents, pigments, rubber chemicals, pharmaceuticals, fragrances, fibers, resins, agricultural chemicals, explosives, and insect repellents. The styrene monomer, derived from benzene and ethylene, is particularly sought after for producing polystyrene used in electronics casings, insulation, and containers. Benzene also contributes to the production of nylon, polycarbonate, and polyurethane.

Properties of Benzene

With a melting point of 5.5°C and boiling point of 80.1°C, benzene’s volatility and flammability are notable. Its structure, a hexagonal ring (C₆H₆) with a molecular weight of 78.11 and density of 0.8765 g/cm³, showcases equal carbon bond distances due to delocalized pi-electrons, symbolized at times by a circle within a hexagon. When part of a substituent, this ring is termed a phenyl group or Ph.

Other Information on Benzene

1. Substitution Reaction of Benzene

Benzene primarily undergoes substitution rather than addition reactions. Examples include halogenation, yielding chlorobenzene and bromobenzene; sulfonation, producing benzene sulfonic acid; nitration, leading to nitrobenzene; and processes like alkylation and acetylation.

2. Addition Reaction of Benzene

Under ultraviolet light, benzene reacts with chlorine to form benzene hexachloride, also known as 1,2,3,4,5,6-hexachlorocyclohexane. Hydrogenation of benzene yields cyclohexane.

3. Benzene Synthesis

Benzene is synthesized by catalytic reaction of hydrocarbons with hydrogen, forming aromatic hydrocarbons through ring formation and hydrogen loss. Additionally, benzene and xylene can be derived from toluene, or benzene can be produced from acetylene using a catalyst. This versatility makes benzene an economically significant chemical raw material.

What Is Benzaldehyde?

Benzaldehyde, with the chemical formula C₇H₆O, is an aromatic aldehyde found naturally. It is the primary component of the essential oils from peach and apricot kernels, known for its almond-like fragrance.

This compound is prone to oxidation, transforming into benzoic acid upon exposure to air. Classified as a hazardous substance, Class 4, flammable liquid, petroleum No. 2, hazardous rank III under various regulations, it poses a flammability risk.

Uses of Benzaldehyde

Benzaldehyde’s almond scent makes it popular in soaps and cosmetics. It is industrially produced from benzal chloride, derived from toluene chlorination, making it cost-effective for widespread use. Beyond fragrances, its reactivity as an aldehyde makes it valuable in synthesizing dyes, pharmaceuticals, and other chemicals.

Properties of Benzaldehyde

With a molecular weight of 106.12 and CAS number 100-52-7, benzaldehyde is a colorless to light yellowish-brown liquid with a distinctive odor. It has a melting point of -26°C, a boiling point of 180°C, and a flash point of 62°C. Its vapor pressure is 150 Pa, and it has a density of 1.041-1.050 g/mL.

Chemical Properties

Highly soluble in ethanol and diethyl ether, it barely dissolves in water. It’s stable under normal conditions but sensitive to light. When stored, it should be kept away from heat, light, and oxidizing agents to prevent hazardous conditions.

Other Information on Benzaldehyde

Safety Measures

Benzaldehyde can irritate eyes and respiratory systems and is harmful if ingested. Long-term exposure may affect the central nervous system, blood, liver, and lungs, and it is toxic to aquatic life. Immediate medical attention is advised if exposure occurs.

Handling and Storage

Appropriate protective gear and ventilation are crucial when handling benzaldehyde. Storage should be in a cool, ventilated area away from light and oxidizers. Special precautions, like a yellow card, are necessary for transportation to avoid contamination with food or feed.

Disposal Guidelines

Disposal should minimize hazard levels through detoxification and neutralization, adhering to relevant laws and regulations. Containers must be thoroughly emptied and properly disposed of or recycled.

What Is Benzyl Alcohol?

Benzyl alcohol is a volatile aromatic alcohol with the molecular formula C₆H₅CH₂OH. This clear, colorless liquid is known for its weak, characteristic aroma. It is insoluble in water but miscible with many organic solvents.

It naturally occurs as an esterified component in essential oils from jasmine, hyacinth, acacia, ylang-ylang, and other flowers.

Uses of Benzyl Alcohol

Benzyl alcohol’s versatility is evident in its application across fragrances, solvents, pharmaceuticals, and as intermediates in chemical synthesis.

1. Fragrance

Known for its almond-like aroma, it’s used in cosmetics, soaps, perfumes, and food flavoring.

2. Solvent

It serves as an alternative to methylene chloride for paint film and floor wax removal, besides being a solvent in paints, adhesives, and inks.

3. Chemical Synthesis

As an intermediate, it’s crucial in synthesizing benzaldehyde and benzylamine, among others, and as a benzylating agent or a protective group in syntheses.

Its roles extend to being a solvent and diluent in ester production, agrochemicals, inks, lacquers, cellulose derivatives, and as an auxiliary in dyeing hydrophobic fibers like acrylics. Its utility in cosmetics, food additives, pharmaceutical ingredients, and anesthetics further showcases its importance.

Properties of Benzyl Alcohol

This liquid’s boiling point is 205°C, with a melting point of -15°C, and a specific gravity of 1.045. Its weak aroma resembles almonds, and though slightly insoluble in water, it dissolves well in ethanol, ether, chloroform, and acetone. Stable under light and heat, benzyl alcohol can oxidize in air.

While generally low in toxicity, it may irritate skin and eyes at high concentrations, and oral ingestion has been linked to poisoning, necessitating careful handling.

In organic synthesis, its capacity for oxidation to benzaldehyde and reduction to benzylamine highlights its significant reactivity.

Structure of Benzyl Alcohol

With a molecular formula of C7H8O and a weight of 108.14, it combines a benzene ring and a hydroxyl group, offering unique solubility and reactivity. This structure, balancing the benzene ring’s resonance stability and the hydroxyl group’s polarity, enables good solubility in organic solvents and utility in synthetic reactions.

Other Information on Benzyl Alcohol

Benzyl Alcohol Production Method

Produced predominantly through halogenation and reduction of toluene, this method involves creating benzyl halides and then reducing them with bases like potassium or sodium hydroxide. Alternative synthesis routes include the Canizaro reaction, the Friedel-Crafts reaction, and the reductive amination of nitrobenzene.

What Is Heptane?

Heptane, a colorless and clear liquid, is known for its specific odor. It falls under various classifications for hazardous materials, including “Hazardous Substance Class 1, Petroleum No. 1, Hazardous Rank II” under the Fire Service Act and is recognized under several regulations for its handling and transportation due to its hazardous nature.

Uses of Heptane

As a solvent, heptane (n-heptane) is utilized in polyolefin polymerization, adhesives, paints, inks, and for extracting oils and fats. It also serves as a thinner, a measuring reagent in spectroscopic and gas chromatography analyses, and in determining the octane number of gasoline. Its role as a cleaning agent in research experiments highlights its versatility in scientific applications.

Heptane Properties

n-Heptane is characterized by a melting point of -91°C, a boiling point of 98°C, a flash point of -1°C, and a spontaneous combustion point of 204°C. Known for its volatility and petroleum odor, n-heptane’s solubility in ethanol and diethyl ether contrasts with its insolubility in water. Its CAS registration number is 142-82-5.

Heptane Structure

Heptane has 11 isomers, including n-heptane, which is a linear alkane with the chemical formula CH₃(CH₂)₅CH₃ and a molecular weight of 100.20. Notably, n-heptane is used as an indicator of octane number 0.

Other Information on Heptane

1. Structural Isomer of Heptane (Main Chain: C7)

n-Heptane, distinguished by having seven carbon atoms in its main chain, is the only heptane isomer in this category.

2. Structural Isomer of Heptane (Main Chain: C6)

2-methylhexane and 3-methylhexane, both with six carbon atoms in the main chain, represent this category. 2-methylhexane is also known as isoheptane.

3. Structural Isomer of Heptane (Main Chain: C5)

3-ethylpentane, with one side chain, and four types with two side chains—2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, and 3,3-dimethylpentane—constitute this group. 2,2-dimethylpentane is also referred to as neoheptane.

4. Structural Isomer of Heptane (Main Chain: C4)

2,2,3-trimethylbutane is the sole heptane type with four carbon atoms in the main chain and three in the side chains.

5. Stereoisomers of Heptane

Considering stereoisomers, there are 11 for heptane. For instance, 3-methylhexane exists as (3R)-3-methylhexane and (3S)-3-methylhexane, while 2,3-dimethylpentane has (3R)-2,3-dimethylpentane and (3S)-2,3-dimethylpentane. These compounds illustrate the smallest alkanes possessing a chiral carbon.

What Is Hexenal?

Figure 1. Basic Information on Trans-2-Hexenal

Hexenal, an organic compound with the formula C₆H₁₀O, includes isomers like trans-2-hexenal and cis-3-hexenal, also known as Aoba-Aldehydes. It has a molecular weight of 98.14 g/mol.

Uses of Hexenal

The isomers, notably trans-2-hexenal and cis-3-hexenal, contribute to grass and leaf fragrances, serving as flavoring agents. Although both have plant aromas, trans-2-hexenal is preferred for its aromatic quality over the unpleasant odor of cis-3-hexenal.

Properties of Hexenal

Trans-2-hexenal, a colorless to yellow liquid, melts at -39.8°C, boils at 146°C, and has a flash point of 43°C. It dissolves in acetone and ethanol but is nearly insoluble in water. Cis-3-hexenal boils at 126°C.

Structure of Hexenal

Figure 2. Basic Information on Cis-3-Hexenal

As aliphatic aldehydes, trans-2-hexenal and cis-3-hexenal have densities of 0.846 g/mL and 0.851 g/mL at 25°C, respectively. Cis-3-hexenal can isomerize to trans-2-hexenal, with its alcohol form, cis-3-hexen-1-ol, being a stable and commonly used fragrance.

Other Information on Hexenal

1. History of Hexenal

The identity of tree fragrance during the fresh green season was first explored by Reinke around 1870 through essential oils. Theodor Curtius identified 2-hexenal in 1912, which Akinawa Hatanaka in 1960 confirmed as the same as the Aoba aldehyde from tea.

2. Natural Hexenal

Trans-2-hexenal is found in various vegetables and fruits, making up the stink bug odor. Cis-3-hexenal, prevalent in many plants and used as a pheromone by insects, contributes to the aroma of tomatoes and other produce.

3. Synthetic Method of Hexenal

Figure 3. Synthesis of Hexenal

Trans-2-hexenal and cis-3-hexenal are synthesized from ethyl vinyl ether and 3-hexen-1-ol, respectively, with cis-3-hexenal also biosynthesized from linolenic acid.