Difluoromethane
[CAS 75-10-5]

Identification

• Classification: Pharmaceutical intermediate >> Heterocyclic compound intermediate >> Pyran compound
• Name: Difluoromethane
• Molecular Formula: CH₂F₂
• Molecular Weight: 52.02
• CAS Registry Number: 75-10-5 (2154-59-8)
• EC Number: 200-839-4
• SMILES: C(F)F

Properties

• Density: 0.9±0.1 g/cm³ Calc.^*, 1.1 g/mL (Expl.)
• Melting point: -136 °C (Expl.)
• Boiling point: -62.2±8.0 °C 760 mmHg (Calc.)^*, -51.6 °C (Expl.)
• Flash point: -78.5±6.3 °C (Calc.)^*
• Index of refraction: 1.196 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS02;GHS04;GHS08 DangerGHS02;GHS02
• Risk Statements: H220-H221-H280-H340-H350
• Safety Statements: P203-P210-P222-P280-P318-P377-P381-P403-P405-P410+P403-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Gases under pressure (liquid)	Press. Gas (Liq.)		H280
Flammable gases	Flam. Gas	1	H220
Gases under pressure (compressed)	Press. Gas (Comp.)		H280
Carcinogenicity	Carc.	1A	H350
Germ cell mutagenicity	Muta.	1B	H340

• Transport Information: UN 3252

chemBlink Chemical Story

Difluoromethane, CAS 75-10-5, is the small fluorocarbon CH2F2, widely known in refrigeration as HFC-32 or R-32. NIST lists a molecular weight of 52.0234 and records R-32 among its established names. Unlike older chlorofluorocarbon refrigerants, difluoromethane contains no chlorine and therefore does not directly participate in stratospheric ozone depletion through chlorine release.

Its principal modern importance comes from refrigeration and air conditioning. R-32 has useful thermodynamic properties and is used both by itself and as a component of refrigerant blends. For example, R-410A is a blend containing R-32 and pentafluoroethane (R-125). The relatively high volumetric refrigeration capacity of R-32 allows compact systems, while its heat-transfer characteristics can support efficient equipment design.

Environmental tradeoffs are central to the R-32 story. It has zero ozone-depletion potential, but it is still a hydrofluorocarbon greenhouse gas. Its climate impact per kilogram is substantially lower than that of several older high-GWP HFC refrigerants, which has encouraged adoption in equipment designed for it. It is not, however, climate-neutral.

Another important difference is flammability. R-32 is classified as an A2L refrigerant: lower toxicity with mild flammability. That classification affects equipment design, charge limits, installation practices and service procedures. A refrigerant cannot be substituted safely on the basis of pressure or cooling performance alone; the system must be designed and approved for its physical and safety properties.

Difluoromethane therefore illustrates the changing priorities of refrigerant chemistry. Earlier generations focused strongly on stability, nonflammability and performance; later choices also had to address ozone depletion and greenhouse impact. R-32 represents one stage in that transition: chlorine-free, efficient and lower in global-warming impact than several refrigerants it can help replace, but still requiring management of both flammability and HFC emissions.

References:
1. NIST Chemistry WebBook, Difluoromethane, CAS 75-10-5.
2. U.S. EPA, Overview of Greenhouse Gases: Hydrofluorocarbons.
3. ASHRAE Standard 34, Designation and Safety Classification of Refrigerants.

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