Cis-1,4-dichloro-2-butene is an important organic chemical intermediate with the molecular formula C4H6Cl2 and CAS number 1476-11-5. This compound serves as a critical building block in the chemical industry, playing a vital role in the synthesis of numerous industrial chemicals. As a dichloroalkene, it contains two chlorine atoms positioned at the 1 and 4 positions of a four-carbon chain with a double bond between carbons 2 and 3, giving it unique chemical reactivity that makes it valuable for various organic synthesis applications.

What is Cis-1,4-Dichloro-2-butene?

Cis-1,4-dichloro-2-butene is an organochlorine compound featuring a cis configuration at its double bond. It appears as a colorless to light yellow liquid at room temperature and is characterized by its reactive chlorine atoms, which make it an excellent electrophile in substitution reactions. The compound has a molecular weight of approximately 125 g/mol and is also known by alternative names including 1,4-dichloro-2-butene and dichlorobutene.

This chemical exists as one of the isomers of 1,4-dichloro-2-butene, with the trans isomer (CAS 110-57-6) being more common in commercial mixtures. The cis configuration refers to the spatial arrangement where both chlorine atoms are on the same side of the double bond, which influences the compound’s reactivity and physical properties.

Chemical Properties and Specifications

Cis-1,4-dichloro-2-butene exhibits several important chemical properties that determine its handling and applications:

• Молекулярная формула: C4H6Cl2
• Molecular Weight: 124.996 g/mol
• CAS Number: 1476-11-5
• Внешний вид: Бесцветная или светло-желтая жидкость
• Чистота: Typically >95% (up to 99% available)
• EINECS Number: 216-021-5
• MDL Number: MFCD00062950

The compound reacts slowly with water to form hydrochloric acid, which is an important consideration for storage and handling. This hydrolysis reaction means that the compound must be kept dry and away from moisture-containing environments to maintain its integrity and reactivity.

Industrial Applications and Uses

Cis-1,4-dichloro-2-butene serves as a fundamental chemical intermediate in the production of numerous important industrial chemicals. Its dual chlorine substituents make it particularly valuable for nucleophilic substitution reactions where the chlorine atoms can be replaced by other functional groups.

Chloroprene Production

One of the primary industrial applications of cis-1,4-dichloro-2-butene is as an intermediate in the production of chloroprene (2-chloro-1,3-butadiene), which is the monomer used to manufacture polychloroprene rubber (neoprene). Chloroprene rubber is widely used in various applications due to its excellent resistance to oils, chemicals, weathering, and temperature extremes. The automotive, construction, and manufacturing industries rely heavily on polychloroprene rubber for seals, hoses, belts, and other components.

Adiponitrile Synthesis

cis-1,4-Dichloro-2-butene is used as a starting material in the production of adiponitrile, a key intermediate in the manufacture of hexamethylenediamine, which is essential for producing nylon 6,6. This application is particularly important in the textile and plastic industries, where nylon 6,6 is used extensively for fibers, automotive parts, and engineering plastics.

1,4-Butanediol and THF Production

The compound serves as a precursor in the synthesis of 1,4-butanediol (BDO), a versatile chemical used in the production of tetrahydrofuran (THF), polybutylene terephthalate (PBT), and other polymers. THF is an important solvent in the pharmaceutical and chemical industries, while BDO itself is used in the manufacture of elastic fibers, plastics, and coatings.

Acrylonitrile Manufacturing

In the chemical industry, cis-1,4-dichloro-2-butene contributes to the production of acrylonitrile, a vital monomer for creating acrylic fibers, nitrile rubber, and various plastic products. Acrylonitrile-butadiene-styrene (ABS) resins, for example, are widely used in consumer electronics, automotive components, and construction materials.

Фармацевтические промежуточные продукты

In organic synthesis research, cis-1,4-dichloro-2-butene has been employed in the preparation of functionalized 3,5-disubstituted cyclopent-2-enones, which are valuable intermediates in pharmaceutical compound synthesis. The pharmaceutical industry utilizes this compound for developing various active pharmaceutical ingredients (APIs) and research chemicals.

Safety and Hazards

Understanding the safety considerations for cis-1,4-dichloro-2-butene is essential for anyone handling this chemical. The compound is classified as highly toxic and requires strict adherence to safety protocols.

Health Effects

Exposure to cis-1,4-dichloro-2-butene poses significant health risks:

• Acute Toxicity: The compound is highly toxic by inhalation, ingestion, and skin absorption. Even brief exposure can lead to serious health effects.
• Skin Contact: Direct skin contact with the liquid causes severe blistering and chemical burns. The compound can be absorbed through the skin, contributing to systemic toxicity.
• Eye Irritation: The compound is a potent lachrymator, causing severe eye irritation and tearing. Contact can result in serious eye damage.
• Respiratory Effects: Inhalation of vapors can cause corrosive injuries to the upper respiratory tract and lungs. High exposure levels may lead to pulmonary edema, a life-threatening condition.
• Genetic Damage: According to toxicological studies, cis-1,4-dichloro-2-butene may induce genetic damage in germ cells, indicating potential reproductive and mutagenic concerns.

Chemical Hazards

When heated, cis-1,4-dichloro-2-butene decomposes to produce toxic gases, including phosgene (a highly toxic carbonyl chloride) and hydrogen chloride. These decomposition products pose additional inhalation hazards during fires or thermal processing. The compound’s reactivity with water also generates hydrochloric acid, which can create corrosive conditions in storage or spill scenarios.

Handling and Storage Requirements

Proper handling procedures are critical when working with cis-1,4-dichloro-2-butene:

• Always wear appropriate personal protective equipment (PPE), including chemical-resistant gloves, safety goggles or face shield, and protective clothing.
• Work in a well-ventilated area or use local exhaust ventilation to prevent vapor accumulation.
• Use respiratory protection when working with the compound in enclosed spaces or during potential high-exposure activities.
• Store in a cool, dry, well-ventilated area away from water and moisture sources.
• Keep containers tightly closed and properly labeled.
• Have emergency eyewash stations and safety showers readily available in the work area.
• Follow all local and federal regulations for hazardous chemical handling and disposal.

Заключение

Cis-1,4-dichloro-2-butene (CAS 1476-11-5) is a valuable chemical intermediate in the industrial chemical sector, essential for producing chloroprene rubber, adiponitrile, 1,4-butanediol, tetrahydrofuran, and acrylonitrile. These downstream products support numerous industries including automotive, construction, textiles, and pharmaceuticals. However, its high toxicity and potential health hazards require careful handling, appropriate safety measures, and proper training for anyone working with this compound. Understanding both its industrial importance and safety requirements is essential for maximizing its utility while minimizing risks.