1,1-Dichloroethylene, commonly called vinylidene chloride or 1,1-DCE, is an

organochloride Organochlorine chemistry is concerned with the properties of organochlorine compounds, or organochlorides, organic compounds that contain one or more carbon–chlorine bonds. The chloroalkane class (alkanes with one or more hydrogens substituted ...

with the molecular formula . It is a colorless liquid with a sharp odor. Like most chlorocarbons, it is poorly soluble in water but soluble in organic solvents. 1,1-DCE was the precursor to the original clingwrap, Saran, for food, but this application has been phased out.

Production

1,1-DCE is produced by dehydrochlorination of

1,1,2-trichloroethane 1,1,2-Trichloroethane, vinyl trichloride or 1,1,2-TCA, is an organochloride solvent with the molecular formula and the structural formula . It is a colourless, sweet-smelling liquid that does not dissolve in water, but is soluble in most organic ...

, a relatively unwanted byproduct in the production of

1,1,1-trichloroethane 1,1,1-Trichloroethane, also known as methyl chloroform and chlorothene, is a chloroalkane with the chemical formula CH3CCl3. It is an isomer of 1,1,2-trichloroethane. A colourless and sweet-smelling liquid, it was once produced industrially i ...

and

1,2-dichloroethane The chemical compound 1,2-dichloroethane, commonly known as ethylene dichloride (EDC), is a chlorinated hydrocarbon. It is a colourless liquid with a chloroform-like odour. The most common use of 1,2-dichloroethane is in the production of vinyl ...

. The conversion is a base-catalyzed reaction which uses either NaOH or Ca(OH) with temperature ca. 100 °C. :ClCHCHCl + NaOH → ClC=CH + NaCl + HO The gas phase reaction, without the base, would be more desirable but is less selective.

Applications

1,1-DCE is mainly used as a comonomer in the polymerization of

vinyl chloride Vinyl chloride is an organochloride with the formula H2C =CHCl. It is also called vinyl chloride monomer (VCM) or chloroethene. It is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC). Vinyl chloride is a ...

acrylonitrile Acrylonitrile is an organic compound with the formula and the structure . It is a colorless, volatile liquid. It has a pungent odor of garlic or onions. Its molecular structure consists of a vinyl group () linked to a nitrile (). It is an im ...

, and

acrylate Acrylates (IUPAC: prop-2-enoates) are the salts, esters, and conjugate bases of acrylic acid. The acrylate ion is the anion . Often, acrylate refers to esters of acrylic acid, the most common member being methyl acrylate. These acrylates contain ...

s. It is also used in

semiconductor device fabrication Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically integrated circuits (ICs) such as microprocessors, microcontrollers, and memories (such as Random-access memory, RAM and flash memory). It is a ...

for growing high purity

silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundan ...

(SiO)

films A film, also known as a movie or motion picture, is a work of Visual arts, visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, emotions, or atmosphere through the use of moving images that are gen ...

Polyvinylidene chloride

As with many other

alkene In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as Alpha-olefin, α-olefins. The Internationa ...

s, 1,1-DCE can be polymerised to form polyvinylidene chloride. A very widely used product, cling wrap, or Saran was made from this

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

. During the 1990s research suggested that, in common with many chlorinated carbon compounds, Saran posed a possible danger to health by leaching, especially on exposure to food in microwave ovens. Accordingly, SC Johnson changed their formulation of Saran Wrap in 2004 to a form of

polyethylene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bott ...

Safety

The health effects from exposure to vinylidene chloride are primarily on the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

, including symptoms of sedation, inebriation, convulsions, spasms, and unconsciousness at high concentrations.

International Agency for Research on Cancer The International Agency for Research on Cancer (IARC; ) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and coordinate research into the causes of cancer. It also cance ...

has put vinylidene chloride in Class 2B, meaning possibly carcinogenic to humans.

National Institute for Occupational Safety and Health The National Institute for Occupational Safety and Health (NIOSH, ) is the List of United States federal agencies, United States federal agency responsible for conducting research and making recommendations for the prevention of work-related occ ...

considers vinylidene chloride a potential occupational

carcinogen A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...

.CDC - NIOSH Pocket Guide to Chemical Hazards
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References

External links

Agency for Toxic Substances and Disease Registry The Agency for Toxic Substances and Disease Registry (ATSDR) is a federal public health agency within the U.S. Department of Health and Human Services (HHS). The agency focuses on minimizing human health risks associated with exposure to hazar ...