Quick Search
1,1-Dichloroethylene, identified in industrial chemistry, polymer synthesis, and chemical engineering by the molecular formula C2H2Cl2, is a synthetic organic compound belonging to the class of chlorinated alkenes and organochlorides.
1,1-Dichloroethylene, being a colorless and highly volatile liquid with a sweetish chlorine odor at room temperature, stands out for high reactivity and polymerization capability.
1,1-Dichloroethylene plays a strategic role in the chemical industry primarily as a monomer in the synthesis of copolymers, an intermediate in packaging copolymer production, and a processing agent in industrial polymerization reactors.
CAS Registry Number: 75-35-4.
EC / EINECS Number: 200-864-0.
PubChem CID: 6366.
UN Dangerous Goods Number: UN 1303 (Class 3 Flammable Liquid, Inhibited).
Molecular Weight: 96.94 g/mol.
Synonyms: 1,1-Dichloroethylene, 1,1-Dichloroethene, Vinylidene chloride, Vinylidene dichloride, 1,1-DCE, 1,1-DCEthene, Ethene, 1,1-dichloro-, VDC.
Key Properties, Physicochemistry, and Identifiers
Density: 1.213 g/cm3 at 20 °C.
Melting Point: -122.5 °C.
Boiling Point: 31.7 °C.
Flash Point: -25 °C (Closed cup).
Vapor Pressure: 66.5 kPa at 20 °C.
Water Solubility: Sparingly soluble in water (2.5 g/L at 20 °C).
Solubility in Organic Solvents: Fully miscible with organic solvents such as ethanol, diethyl ether, acetone, benzene, and chloroform.
Thermal Decomposition: 1,1-Dichloroethylene decomposes into toxic phosgene and hydrogen chloride gases upon exposure to high temperatures or open flames.
Food Additive Status: 1,1-Dichloroethylene is strictly not suitable for food additive use or human consumption (No E-number).
Manufacturing Processes and Chemical Synthesis
1. Dehydrochlorination of 1,1,2-Trichloroethane: 1,1-Dichloroethylene is synthesized on an industrial scale mostly via the dehydrochlorination reaction of 1,1,2-trichloroethane with aqueous alkali solutions such as sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH)2).
2. Thermal Dechlorination: 1,1-Dichloroethylene can also be obtained via catalytic thermal cracking of 1,1,2-trichloroethane at high temperatures to eliminate hydrogen chloride (HCl).
3. Purification and Inhibitor Addition: Crude 1,1-Dichloroethylene obtained from the reaction mixture is purified by distillation and stored with added inhibitors such as p-methoxyphenol (MEHQ) to prevent spontaneous explosive peroxide formation and polymerization.
Applications and Industrial Uses
1. PVDC Polymer Production: The primary industrial application of 1,1-Dichloroethylene is its use as a monomer in copolymerization with vinyl chloride or acrylonitrile to synthesize polyvinylidene chloride (PVDC / Saran) resins and packaging films.
2. Synthesis of Barrier Coatings: 1,1-Dichloroethylene is utilized in producing specialized copolymers that provide high gas and moisture barrier properties in food packaging, pharmaceutical packaging, and paper coatings.
3. Synthetic Fibers and Textile Additives: 1,1-Dichloroethylene serves as a reactant in the synthesis of flame-retardant modacrylic fibers and non-woven fabric binders.
4. Semiconductor Manufacturing: 1,1-Dichloroethylene is used in the electronics industry as a thermal oxidation gas component in synthesizing high-purity silicon oxide films.
5. Chemical Intermediate: 1,1-Dichloroethylene is evaluated as a building block reactant in the synthesis of fluorinated compounds and specialized chlorinated chemicals.
6. Surface Coating Resins: 1,1-Dichloroethylene is utilized in manufacturing corrosion-resistant protective lining resins and plastic latex components.
Safety, Toxicology, and Storage Standards
Hazard Classification: According to GHS standards, 1,1-Dichloroethylene is classified as Extremely Flammable Liquid (Category 1), Acute Toxicity (Inhalation Category 4), Carcinogenicity (Category 2), and Specific Target Organ Toxicity - Repeated Exposure (Category 2, Liver and Kidney).
Health Risks and Toxicity: Inhalation of 1,1-Dichloroethylene vapors depresses the central nervous system, leading to dizziness, narcosis, and liver/kidney damage at high doses.
Contact Risk: Dermal and ocular contact with 1,1-Dichloroethylene presents a risk of irritation and chemical tissue damage.
EHS and Storage Conditions: 1,1-Dichloroethylene must be kept strictly away from static electricity sparks, open flames, air (oxygen), and heat sources.
Chemical Incompatibility: 1,1-Dichloroethylene can form explosive peroxides upon contact with air; 1,1-Dichloroethylene reacts violently with strong oxidizers, alkali metals, and copper compounds.
Storage Standards: 1,1-Dichloroethylene must be stored in a cool environment in sealed steel containers under a nitrogen blanket equipped with proper inhibitor levels, static grounding, proper ventilation, and explosion-proof systems.
