月: 2023年1月

What Is Propane Gas?

Propane is a saturated chain hydrocarbon, a colorless flammable gas (odorless in its pure form) with a weak characteristic odor.

Its chemical formula is C₃H₈, its molecular weight is 44.09, and its CAS number is 74-98-6. Propane is a chemical used primarily as a gaseous fuel and was discovered in 1857 by the French chemist Marcellin Berthelot.

Uses of Propane Gas

Propane gas is primarily utilized as a fuel in various applications due to its chemical properties.

Properties of Propane Gas

Propane has distinct physical and chemical characteristics that make it suitable for a range of applications.

1. Physical Properties

Propane exhibits specific physical properties making it distinct from other gases.

• Melting Point: -187.6°C
• Boiling Point: -42.1°C
• Density: 1.5 times heavier than air
• Solubility: Soluble in ether and ethanol, almost insoluble in water (solubility of 62.4 mg/L)

2. Other Features

Propane demonstrates additional noteworthy features.

• Easy Liquefaction: Propane can be readily liquefied.
• Combustion: It burns with a large flame when exposed to heat or fire.
• Anesthetic Effect: Propane in high concentrations has an anesthetic effect.

Uses of Propane Gas

Propane finds various applications across different industries.

1. Gas Fuel

Propane is commonly used as a fuel, either alone or in mixtures with other gases.

2. Refrigerant

Propane serves as a refrigerant in gas absorption refrigeration systems, offering efficient cooling properties.

3. Other Applications

Propane is utilized as a solvent, aerosol agent, and feedstock in chemical synthesis processes.

Other Information on Propane Gas

Additional details regarding propane gas include its manufacturing process, chemical reactions, and legal considerations.

1. Propane Manufacturing Process

Propane is obtained through various methods such as natural gas processing, fractional distillation of petroleum, or cracking of alkanes.

2. Propane Reactions

Although propane’s chemical reactivity is low, it can undergo reactions to form other compounds.

3. Legal Information

Propane is regulated under various laws and regulations due to its hazardous and flammable nature.

4. Handling and Storage Precautions

Proper handling and storage precautions are essential to ensure safety when dealing with propane gas.

• Store in a dedicated high-pressure gas container in a well-ventilated area below 40°C.
• Avoid ignition sources and contact with strong oxidizers.
• Ensure proper sealing of containers after use and wear appropriate protective gear.
• Use propane in well-ventilated areas or with local exhaust ventilation systems.
• Avoid inhalation of vapors to prevent asphyxiation and anesthetic effects.

What Is Butene?

Butene is an unsaturated hydrocarbon with one double bond, whose molecular formula is represented by C₄H₈.

There are three isomers: 1-butene, 2-butene, and isobutene; two types of 2-butene exist: CIS-2-butene and trans-2-butene. Both are colorless gases with an odor characteristic of olefin gas and have a molecular weight of 56.10 g/mol.

Butene is present in the C4 fraction of the naphtha cracking process or the by-product C4 fraction of oil catalytic cracking and can be separated by distillation, among others. 1-butene and 2-butene are often used as liquefied petroleum gas in a mixed form.

Uses of Butene

The main uses of isomers of butene are as follows

• 1-Butene
  It has a highly reactive double bond and is an important raw material in the petrochemical industry. It is used as a liquefied petroleum gas for fuel and as a synthetic raw material for the production of butyl alcohol, ethyl methyl ketone, and pentanol, which are used to make butyl alcohol and butadiene.
• 2-Butene
  Industrially, it is used as an n-butene mixture, not separated from 1-butene.
• Isobutene
  In addition to being used as a raw material for the production of isooctane and polymerized gasoline, isobutene is also used as a raw material for the production of synthetic rubber and alkyl halides.

Properties of Butene

1-butene has a melting point of -185.3°C, a boiling point of -6.3°C, and an ignition point of 384°C. It is soluble in ethanol, benzene, and diethyl ether.

CIS-2-butene has a melting point of -138.9°C and a boiling point of 3.7°C. Trans-2-butene has a melting point of -105.5°C and a boiling point of 0.9°C. Due to their very close boiling points, isomers are difficult to separate by distillation but often do not need to be separated because they exhibit similar reactivity. Typically, 2-butene is commercially available as a mixture of 70% cis and 30% trans.

Isobutene has a melting point of -140.3°C and a boiling point of -6.9°C.

Butene Structure

1-butene is a linear α-alkene. Its differential formula is CH₃CH₂CH=CH₂ and its density is 0.62 g/cm³.

2-butene is the simplest alkene with geometrical isomerism and is represented by the differential formula CH₃CH=CHCH₃. cis-2-butene at 3.7°C has a density of 0.641 g/cm³ and trans-2-butene at 0.9°C has a density of 0.626 g/cm³. Cis-2-butene is also called cis-β-butylene and trans-2-butene is also called trans-β-butylene.

Isobutene has a structure in which two methyl groups are bonded to one carbon atom of ethylene. Its specific formula is CH₂=C(CH₃)₂ and its density is 0.5879 g/cm³.

Other Information on Butene

1. Synthesis of Butene

Separation of crude C4 fractions yields a mixture of 1-butene and 2-butene. Dimerization of ethylene produces only terminal alkenes. It can be purified to high purity by distillation.

Isobutene can be isolated by reaction with sulfuric acid in the petroleum refining stream. It can usually be produced by catalytic dehydrogenation of isobutane. It can also be produced from acetone, cellulose, and xylose. Isobutene is also produced as a byproduct of the ethenolysis of diisobutylene during the synthesis of neohexene.

2. Butene Reaction

1-butene is easily polymerized to form polybutene. It is a raw material for the production of linear polyethylene and can be used as a precursor for polypropylene resin, methyl ethyl ketone, and epoxy butane.

Butadiene can be produced from 2-butene. Hydration reaction yields 2-butanol, which is oxidized to methyl ethyl ketone.

Isobutene is a raw material for methacrolein. The addition of methanol or ethanol to isobutene yields methyl tert-butyl ether or ethyl tert-butyl ether. Commercially tert-butylamine is also produced by zeolite-catalyzed amination of isobutylene. Polyisobutylene is produced when isobutene is polymerized, and isooctane can be synthesized by alkylation of isobutene. Friedel-Crafts reactions with phenol and 4-methoxyphenol yield dibutylhydroxytoluene and butylhydroxyanisole from isobutene.

What Is Butanediol?

Butanediol is a divalent alcohol whose molecular formula is C₄H₁₀O₂.

In addition to the widely used 1,4-butanediol, there are four other isomers of butanediol: 1,2-butanediol, 1,3-butanediol, and 2,3-butanediol.

1,4-butanediol is classified as “acute toxicity (oral)” in the GHS classification. 

Uses of Butanediol

The uses of butanediol vary with each isomer, and all isomers are widely used in industry.

Typical applications for each isomer include 1,2-butanediol as a raw material for resins and amino acids, and 1,3-butanediol as a solvent, raw material for resins, and cosmetic additive. 1,4-butanediol can be used as a raw material for resins and solvents, and 2,3-butanediol as a raw material for pharmaceuticals and cosmetics.

In particular, 1,4-butanediol is an industrially important compound, as it is a raw material for tetrahydrofuran and γ-butyrolactone, which are widely used solvents in general.

Properties of Butanediol

1,2-butanediol has a melting point of -50°C, a boiling point of 195-196.9°C, and a density of 1.0023 g/cm³. 1,3-butanediol acts as a hypoglycemic agent for organisms and is converted to beta-hydroxybutyrate, which acts as a substrate for brain metabolism.

1,4-butanediol has a melting point of 20°C, a boiling point of 230°C, and a density of 1.010 g/cm³. In the body, 1,4-butanediol is metabolized to gamma-hydroxybutyrate. 2,3-butanediol has a melting point of 7.6°C, a boiling point of about 180°C, and a density of 1.000 to 1.010 g/cm³.

Structure of Butanediol

Butanediol is n-butane with two hydroxyl groups. Its molecular formula is C₄H₁₀O₂ with a molar mass of 90.12 g/mol. 1,1-butanediol, for example, is unstable and quickly dehydrates to butyraldehyde.

In 1,2-butanediol, the carbon at position 2 is the chiral center. It is optically active, and there are two mirror isomers, (R)-1,2-butanediol and (S)-1,2-butanediol. Similarly, 1,3-butanediol has mirror-image isomers. And 2,3-butanediol has three stereoisomers: (2R,3R)-(-)-2,3-butanediol, (2S,3S)-(+)-2,3-butanediol and meso-2,3-butanediol.

Other Information on Butanediol

1. 1,4-Butanediol Synthesis

1,4-butanediol is widely synthesized by hydrogenation of 1,4-butanediol obtained by the Reppe reaction of acetylene and formaldehyde.

1,4-butanediol can also be synthesized by hydrogenation after the conversion of anhydrides such as succinic acid and maleic acid to methyl esters.

2. Reaction of 1,4-Butanediol

1,4-butanediol is a raw material for plastics and fibers such as polybutylene terephthalate. 1,4-butanediol reacts with terephthalic acid to produce polybutylene terephthalate.

As an engineering plastic, polybutylene terephthalate has excellent thermal stability, electrical properties, and dimensional accuracy, and is widely used in automotive and electrical and electronic components.

What Is Butane Gas?

Butane, a colorless gas with a characteristic hydrocarbon odor, has the chemical formula C₄H₁₀ and a molecular weight of 58.12. It exists in two isomers: linear n-butane and branched isobutane, making it one of the smallest alkanes. Discovered by Edward Frankland in 1849, butane serves primarily as a fuel.

Properties of Butane Gas

With a melting point of -138°C and a boiling point of -0.5°C, butane is insoluble in water but dissolves in ethanol, ether, and chloroform. It is highly flammable, presenting significant explosion risks when mixed with air or exposed to heat.

Uses of Butane Gas

Butane’s applications range from industrial fuel, where n-butane enhances gasoline’s octane number, to household uses in lighter fuel and portable stoves. Isobutane, utilized in the production of isoparaffins and as a refrigerant in CFC-free refrigerators, also serves as a component in liquefied petroleum gas (LPG).

Other Information on Butane Gas

1. Butane Manufacturing Process

Produced both in the laboratory and industrially, butane is extracted from petroleum through fractional distillation or as a byproduct in the refining process. It is present in crude oil and obtained during the cracking or reforming of heavy oils.

2. Butane Reaction

Butane combusts to form carbon dioxide and water in the presence of ample oxygen. Under limited oxygen, incomplete combustion yields soot and carbon monoxide. Butane also undergoes reactions to form chlorobutanes via radical mechanisms.

3. Legal Information

While not listed under as a deleterious substances, butane is regulated as a hazardous and flammable gas, necessitating proper labeling and handling precautions.

4. Handling and Storage Precautions

Butane should be stored in high-pressure containers, away from heat sources, with valves securely closed when not in use. It requires handling in well-ventilated or explosion-proof areas, with protective gear to prevent inhalation or skin contact.