1,1-Difluoroethane, or DFE, is an

organofluorine compound Organofluorine chemistry describes the chemistry of organofluorine compounds, organic compounds that contain a carbon–fluorine bond. Organofluorine compounds find diverse applications ranging from oil and water repellents to pharmaceuticals, ...

with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

CHF. This colorless

gas Gas is a state of matter that has neither a fixed volume nor a fixed shape and is a compressible fluid. A ''pure gas'' is made up of individual atoms (e.g. a noble gas like neon) or molecules of either a single type of atom ( elements such as ...

is used as a

refrigerant A refrigerant is a working fluid used in the cooling, heating, or reverse cooling/heating cycles of air conditioning systems and heat pumps, where they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are ...

, where it is often listed as R-152a (refrigerant-152a) or HFC-152a (

hydrofluorocarbon Hydrofluorocarbons (HFCs) are synthetic organic compounds that contain fluorine and hydrogen atoms, and are the most common type of organofluorine compounds. Most are gases at room temperature and pressure. They are frequently used in air condit ...

-152a). It is also used as a propellant for aerosol sprays and in

gas duster A gas duster, also known as compressed air or canned air, is a product used for cleaning or dusting electronic equipment and other sensitive devices that cannot be cleaned using Water#Washing, water. This type of product is most often packaged ...

products. As an alternative to

chlorofluorocarbon Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly Halogenation, halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F). They are produced as volatility (chemistry), volat ...

s, it has an

ozone depletion potential The ozone depletion potential (ODP) of a chemical compound is the relative amount of degradation to the ozone layer it can cause, with trichlorofluoromethane (R-11 or CFC-11) being fixed at an ODP of 1.0. Chlorodifluoromethane (R-22), for examp ...

of zero, a lower

global warming potential Global warming potential (GWP) is a measure of how much heat a greenhouse gas traps in the atmosphere over a specific time period, relative to carbon dioxide (). It is expressed as a multiple of warming caused by the same mass of carbon dioxide ( ...

than other hydrofluorocarbons and a shorter atmospheric lifetime (1.4 years).

Production

1,1-Difluoroethane is a synthetic substance that is produced by the mercury-catalyzed addition of

hydrogen fluoride Hydrogen fluoride (fluorane) is an Inorganic chemistry, inorganic compound with chemical formula . It is a very poisonous, colorless gas or liquid that dissolves in water to yield hydrofluoric acid. It is the principal industrial source of fluori ...

acetylene Acetylene (Chemical nomenclature, systematic name: ethyne) is a chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is u ...

: :HCCH + 2 HF → CHCHF The intermediate in this process is

vinyl fluoride Vinyl fluoride is an organic halide with the chemical formula C2H3F. It is a colorless gas with a faint ether-like odor. It is used as the monomeric precursor to the fluoropolymer polyvinylfluoride. Production It was first prepared in 1901 by F ...

(C₂H₃F), the

monomer A monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or two- or three-dimensional network in a process called polymerization. Classification Chemis ...

ic precursor to

polyvinyl fluoride Polyvinyl fluoride (PVF) or –(CH2CHF)n– is a polymer material mainly used in the flammability-lowering coatings of airplane interiors and photovoltaic module backsheets. It is also used in raincoats and metal sheeting. Polyvinyl fluoride is a ...

Uses

With a relatively low

(GWP) index of 124 and favorable thermophysical properties, 1,1-difluoroethane has been proposed as an environmentally friendly alternative to R134a. Despite its flammability, R152a also presents operating pressures and volumetric cooling capacity (VCC) similar to R134a, so it can be used in large chillers or in more particular applications like

heat pipe A heat pipe is a heat-transfer device that employs phase transition to transfer heat between two solid interfaces. At the hot interface of a heat pipe, a volatile liquid in contact with a thermally conductive solid surface turns into a vapor ...

finned heat exchangers. In addition, 1,1-difluoroethane is also commonly used in

s and numerous other retail aerosol products, particularly those subject to stringent

volatile organic compound Volatile organic compounds (VOCs) are organic compounds that have a high vapor pressure at room temperature. They are common and exist in a variety of settings and products, not limited to Indoor mold, house mold, Upholstery, upholstered furnitur ...

(VOC) requirements. The molecular weight of difluoroethane is 66, making it a useful and convenient tool for detecting vacuum leaks in

gas chromatography–mass spectrometry Gas chromatography–mass spectrometry (GC–MS) is an analytical method that combines the features of gas-chromatography and mass spectrometry to identify different substances within a test sample. Applications of GC–MS include drug detectio ...

(GC-MS) systems. The cheap and freely available gas has a molecular weight and fragmentation pattern (base peak at ''m''/''z'' = 51 in typical EI-MS, major peak at ''m''/''z'' = 65) distinct from anything in air. If mass peaks corresponding to 1,1-difluoroethane are observed immediately after spraying a suspect leak point, leaks may be identified.

Safety

Difluoroethane is an extremely flammable gas, which decomposes rapidly on heating or burning, producing toxic and irritating fumes, including

and

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

. In a

DuPont Dupont, DuPont, Du Pont, duPont, or du Pont may refer to: People * Dupont (surname) Dupont, also spelled as DuPont, duPont, Du Pont, or du Pont is a French surname meaning "of the bridge", historically indicating that the holder of the surname re ...

study, rats were exposed to up to 25,000 ppm (67,485 mg/m) for six hours daily, five days a week for two years. This has become the

no-observed-adverse-effect level The no-observed-adverse-effect level (NOAEL) denotes the level of exposure of an organism, found by experiment or observation, at which there is no biologically or statistically significant increase in the frequency or severity of any adverse effe ...

for this substance. Prolonged exposure to 1,1-difluoroethane has been linked in humans to the development of

coronary disease Coronary artery disease (CAD), also called coronary heart disease (CHD), or ischemic heart disease (IHD), is a type of heart disease involving the reduction of blood flow to the cardiac muscle due to a build-up of atheromatous plaque in the a ...

and

angina Angina, also known as angina pectoris, is chest pain or pressure, usually caused by insufficient blood flow to the heart muscle (myocardium). It is most commonly a symptom of coronary artery disease. Angina is typically the result of parti ...

. Repeated or sufficiently high levels of exposure, particularly purposeful inhalation, can precipitate fatal

cardiac arrhythmia Arrhythmias, also known as cardiac arrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. Essentially, this is anything but normal sinus rhythm. A resting heart rate that is too fast – above 100 beat ...

Abuse

Difluoroethane is an

intoxicant A psychoactive drug, psychopharmaceutical, mind-altering drug, consciousness-altering drug, psychoactive substance, or psychotropic substance is a chemical substance that alters psychological functioning by modulating central nervous system acti ...

with abuse potential. It appears to act primarily through GABA_A and

glutamate Glutamic acid (symbol Glu or E; known as glutamate in its anionic form) is an α-amino acid that is used by almost all living beings in the biosynthesis of proteins. It is a Essential amino acid, non-essential nutrient for humans, meaning that ...

receptors. Fatalities linked to difluoroethane abuse include actress Skye McCole Bartusiak, singer

Aaron Carter Aaron Charles Carter (December 7, 1987November 5, 2022) was an American singer and rapper. He came to fame as a teen pop singer in the late 1990s, establishing himself as a star among preteen and teenage audiences during the first years of th ...

and wrestler Mike Bell.

Bitterant A bitterant (or bittering agent) is a chemical that is added to a product to make it olfaction, smell or taste Taste#Bitterness, bitter. Bitterants are commonly used as aversive agents to discourage the inhalation or ingestion of toxic substances ...

s, added voluntarily to some brands to deter purposeful inhalation, are often not legally required; they do not negate or counteract difluoroethane's intoxicating effects.

Environmental abundance

Most production, use, and emissions of HFC-152a have occurred within Earth's more industrialized and populated northern hemisphere following the substance's introduction in the 1990s. Its concentration in the northern

troposphere The troposphere is the lowest layer of the atmosphere of Earth. It contains 80% of the total mass of the Atmosphere, planetary atmosphere and 99% of the total mass of water vapor and aerosols, and is where most weather phenomena occur. From the ...

reached an annual average of about 10 parts per trillion by year 2011. The concentration of HFC-152a in the southern troposphere is about 50% lower due to its removal rate (i.e. lifetime) of about 1.5 years being similar in magnitude to the global atmospheric mixing time of one to two years.

References