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1,1-Dichloroethane, identified in industrial chemistry, organic synthesis, and chemical engineering by the molecular formula C2H4Cl2, is a synthetic organic compound belonging to the class of chlorinated hydrocarbons and geminal dihalides.
1,1-Dichloroethane, being a colorless and highly volatile liquid with a sweet, chloroform-like odor at room temperature, stands out for high solvent capacity and complete miscibility with organic chemicals.
1,1-Dichloroethane plays a strategic role in the chemical industry primarily as a reaction intermediate in the synthesis of chlorinated compounds, a solvent in specialized extraction processes, and a processing medium in industrial reactors.
CAS Registry Number: 75-34-3.
EC / EINECS Number: 200-863-5.
PubChem CID: 6365.
UN Dangerous Goods Number: UN 2362 (Class 3 Flammable Liquid).
Molecular Weight: 98.96 g/mol.
Synonyms: 1,1-Dichloroethane, Ethylidene chloride, Ethylidene dichloride, 1,1-DCE, Methyl chloromethyl chloride, α,α-Dichloroethane, Ethane, 1,1-dichloro-, Monochloroethyl chloride, Ethylidene bichloride.
Key Properties, Physicochemistry, and Identifiers
Density: 1.175 g/cm3 at 20 °C.
Melting Point: -97 °C.
Boiling Point: 57.3 °C.
Flash Point: -17 °C (Closed cup).
Vapor Pressure: 24.3 kPa at 20 °C.
Water Solubility: Limited solubility in water (5.5 g/L at 20 °C).
Solubility in Organic Solvents: Fully miscible with organic solvents such as ethanol, diethyl ether, benzene, and chloroform.
Thermal Decomposition: 1,1-Dichloroethane decomposes into toxic phosgene and hydrogen chloride gases upon exposure to high temperatures or open flames.
Food Additive Status: 1,1-Dichloroethane is strictly not suitable for food additive use or human consumption (No E-number).
Manufacturing Processes and Chemical Synthesis
1. Hydrochlorination of Vinyl Chloride: 1,1-Dichloroethane is synthesized on an industrial scale mostly by the addition of hydrogen chloride (HCl) to vinyl chloride (C2H3Cl) gas in the presence of Lewis acid catalysts such as aluminum chloride (AlCl3) or iron(III) chloride (FeCl3) (in accordance with Markovnikov's rule).
2. Direct Chlorination of Ethane: 1,1-Dichloroethane can also be obtained via thermal or photochemical radical chlorination of ethane gas; however, this method yields 1,2-dichloroethane and other polychlorinated by-products, thereby requiring precise fractional distillation separation.
3. Purification and Quality Control: Crude 1,1-Dichloroethane obtained from the reaction mixture reaches commercial purity (99%+) through neutralization of acidic residues (HCl), removal of moisture, and subsequent purification in sequential fractional distillation columns.
Applications and Industrial Uses
1. 1,1,1-Trichloroethane Production: The primary industrial application of 1,1-Dichloroethane is its use as a feedstock in the synthesis of the industrial solvent 1,1,1-trichloroethane via dehydrochlorination and further chlorination steps.
2. Synthesis of Specialized Organic Compounds: 1,1-Dichloroethane participates in reactions as a building block for the ethylidene group in the synthesis of pharmaceuticals, agrochemicals, and fine chemicals.
3. Industrial Solvent and Extraction: 1,1-Dichloroethane is utilized as a specialized solvent in dissolving paints, varnishes, rubbers, and high-fat organic substances.
4. Laboratory Applications: 1,1-Dichloroethane is used as a reaction medium and extracting phase in analytical chemistry and organic synthesis research.
5. Historical Applications: 1,1-Dichloroethane was evaluated as an inhalation anesthetic in the early 20th century, but 1,1-Dichloroethane was completely withdrawn from surgical use due to cardiac arrhythmia and potential toxic effects on the liver.
6. Surface Cleaning: 1,1-Dichloroethane serves as a technical solvent component in degreasing precision metal parts and cleaning foundry molds.
Safety, Toxicology, and Storage Standards
Hazard Classification: According to GHS standards, 1,1-Dichloroethane is classified as Flammable Liquid (Category 2), Acute Toxicity (Oral Category 4), Eye Irritation (Category 2A), and Specific Target Organ Toxicity - Single Exposure (Category 3, Respiratory Irritation and Central Nervous System).
Health Risks and Toxicity: Inhalation of 1,1-Dichloroethane vapors depresses the central nervous system, leading to dizziness, drowsiness, nausea, and unconsciousness at high doses.
Contact Risk: Dermal and ocular contact with 1,1-Dichloroethane presents a risk of severe irritation and chemical burns.
EHS and Storage Conditions: 1,1-Dichloroethane must be kept strictly away from static electricity sparks, open flames, and heat sources.
Chemical Incompatibility: 1,1-Dichloroethane reacts violently with strong oxidizers, active metals (sodium, potassium, aluminum powder), and strong bases.
Storage Standards: 1,1-Dichloroethane must be stored in a cool, dry environment in sealed steel drums or tanks equipped with static grounding, proper ventilation, and explosion-proof systems.
