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Introduction
In industrial chemistry, refrigeration systems, and fluorochemical production, Chlorodifluoromethane (HCFC-22 / Freon 22), defined by the molecular formula CHClF₂, is a colorless gas with a faint ether-like odor belonging to the hydrochlorofluorocarbon (HCFC) class.
Chlorodifluoromethane exists as a liquefied gas under low temperature and high pressure.
Chlorodifluoromethane has been widely used as a primary raw material and intermediate in air conditioning systems, industrial refrigeration, and fluoropolymer (especially PTFE / Teflon) synthesis.
CAS Registry Number: 75-45-6.
EC / EINECS Number: 200-871-9.
PubChem CID: 6372.
UN Dangerous Goods Number: UN 1018 (Class 2.2 Non-Flammable, Non-Toxic Gas).
Molecular Weight: 86.47 g/mol.
Synonyms: Chlorodifluoromethane, HCFC-22, R-22, Refrigerant-22, Freon-22, Genetron-22, Monochlorodifluoromethane, Difluorochloromethane, Methane, chlorodifluoro-, CHClF₂.
Basic Properties, Physicochemistry, and Identifiers
Density: Saturated liquid density (at 25 °C) is 1.194 g/cm³; gas density (relative to air) is 3.0 (heavier than air).
Melting Point: -157.4 °C.
Boiling Point: -40.8 °C.
Flash Point: Non-flammable (Does not ignite).
Vapor Pressure: 908 kPa (9.08 bar) at 20 °C.
Solubility in Water: Low solubility in water (approximately 3 g/L at 25 °C).
Solubility in Organic Solvents: Well soluble in ether, acetone, chloroform, and chlorinated hydrocarbons.
Thermal Decomposition: Chlorodifluoromethane decomposes at extremely high temperatures to form toxic gases such as hydrogen fluoride (HF), hydrogen chloride (HCl), and phosgene.
Food Additive Status: Chlorodifluoromethane is strictly unsuitable as a food additive or for human consumption (It has no E-number).
Production Processes and Chemical Synthesis
Chlorodifluoromethane is produced on an industrial scale by the fluorination reaction of chloroform (CHCl₃) with anhydrous hydrogen fluoride (HF) in the presence of an antimony pentachloride catalyst.
The gas mixture leaving the reactor is neutralized and cooled to obtain crude Chlorodifluoromethane.
Chlorodifluoromethane is purified in distillation columns and transferred to storage tanks.
Applications and Industrial Uses
Chlorodifluoromethane was used for many years as the main standard refrigerant in commercial and residential air conditioning systems.
Chlorodifluoromethane is used as a basic raw material in pyrolysis reactions for tetrafluoroethylene (TFE) production, which enables the manufacture of PTFE (Teflon).
Chlorodifluoromethane has functioned as a refrigerant gas in industrial freezing and cold storage facilities.
Chlorodifluoromethane has been evaluated as a foam blowing agent in polyurethane foam manufacturing.
Safety, Toxicology, and Storage Standards
According to GHS standards, Chlorodifluoromethane is classified as Gas Under Pressure and Hazardous to the Ozone Layer (Category 1).
When inhaled in high concentrations, Chlorodifluoromethane acts as a simple asphyxiant, causing oxygen deficiency and dizziness.
Direct contact of the liquid form of Chlorodifluoromethane with the skin and eyes leads to severe frostbite.
Because Chlorodifluoromethane has an Ozone Depletion Potential (ODP), its use is being globally phase-out under the Montreal Protocol.
Chlorodifluoromethane must be kept away from high temperatures, open flames, and spark sources.
Chlorodifluoromethane must be stored in cool, dry, well-ventilated areas and in approved pressurized steel cylinders.
