1,1-Dichloroethylene

1- Dichloroethylene [75-35-4] is more commonly known as vinylidene chloride and is covered ia an article ia the Eniyclopedia by that tide. 

2-Dichloroethylene [540-59-0] (1,2-dichloroethene) is also known as acetylene dichlotide, dioform, a,P-dichloroethylene, and yy -dichloroethylene. It exists as a mixture of two geometric isomers /n j -l,2-dichloroethylene [156-60-5] (1) and i7j -l,2-dichloroethylene [156-59-2] (2). 

The isomeric mixture is a colodess, mobile Hquid with a sweet, slightly irritating odor resembling that of chloroform. It decomposes slowly on exposure to light, air, and moisture. The mixture is soluble ia most hydrocarbons and only slightly soluble ia water. The cis—trans proportions ia a cmde mixture depend on the production conditions. The isomers have distinct physical and chemical properties and can be separated by fractional distillation. 

2- Dichloroethylene consists of a mixture of the cis and trans isomers, as manufactured. The physical properties of both isomeric forms are Hsted ia Table 1. Biaary and ternary a2eotrope data for the cis and trans isomers are given ia Table 2. 

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

Synonyms Acetylene dichloride dichlor-oacetylene 1,2-dichloroethene 

2-Dichloroethylene is used as a solvent for organic materials and as an intermediate in the synthesis of other chlorinated compounds it may be produced by the chlorination of acetylene but is often produced as a by-product in the manufacture of other chlorinated compounds. 

Toxicology. 1,2 -Dichloroethylene central nervous system depression at high concentrations liver, lung, and heart damage have been reported in animal studies. 

2-Dichloroethylene is a mixture of two geometric isomers, cis and trans-, the proportion of the cis isomer to the trans isomer varies from mixture to mixture, depending on the manufacturer s specifications. The properties of the mixture are expected to be similar to those of the individual isomers. 

There has been only one report of industrial poisoning, a fatality caused by very high vapor inhalation in a small enclosure. The isomeric concentration of the vapor was not reported, nor were the level and duration of the exposure or symptoms of toxicity. In another early report, exposure to the trans isomer at 2200ppm caused nausea, drowsiness, fatigue, vertigo, and increased intracranial pressure in two human subjects.  

Coefficient of cubical expaniion Av./ C, liquid 0.001Z7 Boiling rsnge 760 mm Coefficient o cubicsl expansion 47.0-48. 5 C 

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Both chlorines of 1,1-dichloroethylene (340) react stepwise with different terminal alkynes to form the unsymmetrical enediyne 341 [250]. The coupling of the dichloroimine 342 with tin acetylide followed by hydrolysis affords the dialkynyl ketone 343[2511. The phenylthioimidoyl chloride 344 undergoes stepwise reactions with two different tin acetylides to give the dialkynylimine 345[252],... 

Chlorinated by-products of ethylene oxychlorination typically include 1,1,2-trichloroethane chloral [75-87-6] (trichloroacetaldehyde) trichloroethylene [7901-6]-, 1,1-dichloroethane cis- and /n j -l,2-dichloroethylenes [156-59-2 and 156-60-5]-, 1,1-dichloroethylene [75-35-4] (vinyhdene chloride) 2-chloroethanol [107-07-3]-, ethyl chloride vinyl chloride mono-, di-, tri-, and tetrachloromethanes (methyl chloride [74-87-3], methylene chloride [75-09-2], chloroform, and carbon tetrachloride [56-23-5])-, and higher boiling compounds. The production of these compounds should be minimized to lower raw material costs, lessen the task of EDC purification, prevent fouling in the pyrolysis reactor, and minimize by-product handling and disposal. Of particular concern is chloral, because it polymerizes in the presence of strong acids. Chloral must be removed to prevent the formation of soflds which can foul and clog operating lines and controls (78). 

Properties. Pure vinyHdene chloride [75-35-4] (1,1-dichloroethylene) is a colorless, mobile Hquid with a characteristic sweet odor. Its properties are summarized in Table 1. VinyHdene chloride is soluble in most polar and nonpolar organic solvents. Its solubiHty in water (0.25 wt %) is nearly independent of temperature at 16—90°C (4). 

Dehydrochlorination of 1,1,2-trichloroethane [25323-89-1] produces vinyHdene chloride (1,1-dichloroethylene). Addition of hydrogen chloride to vinyHdene chloride in the presence of a Lewis acid, such as ferric chloride, generates 1,1,1-trichloroethane. Thermal chlorination of 1,2-dichloroethane is one route to commercial production of trichloroethylene and tetrachloroethylene. 

Dehydrochlorination of chlorinated derivatives such as 1,1,2-trichloroethane may be carried out with a variety of catalytic materials, including Lewis acids such as aluminum chloride. Refluxing 1,1,2-trichlorethane with aqueous calcium hydroxide or sodium hydroxide produces 1,1-dichloroethylene in good yields (22), although other bases such as magnesium hydroxide have been reported (23). Dehydrochlorination of the 1,1,1-trichloroethane isomer with catalytic amounts of a Lewis acid also yields 1,1-dichloroethylene. Other methods to dehydrochlorinate 1,1,1-trichloroethane include thermal dehydrochlorination (24) and by gas-phase reaction over an alumina catalyst or siUca catalyst (25). 

In a second process, hydrogen chloride is added to 1,1-dichloroethylene in the presence of a FeCl catalyst ... 

Unreacted 1,1-dichloroethylene exits the reactor as vapor and can be condensed and recycled to the reactor. Product 1,1,1-trichloroethane exits the reactor as a Hquid, along with the Lewis acid catalyst, and can be removed from the catalyst by flash distillation. Selectivity is high however, some dehydrochlorination of the product can occur in the distillation step. 

The principal U.S. producers of 1,1,1-trichloroethane include The Dow Chemical Company, PPG Industries Inc., and Vulcan Materials Co. Several European and Japanese companies also produce large amounts aimually. Over 70% of the production is based on the vinyl chloride-1,1-dichloroethane process, 20% on the 1,1-dichloroethylene process, and about 10% on the direct chlorination of ethane. 

Dehydrochlorination 1,1,2-Trichloroethane is easily dehydrochloriaated by a number of catalytic reagents to give 1,1-dichloroethylene and some 1,2-dichloroethylene. Refluxing with aqueous and methanolic solutions of NaOH, Ca(OH)2, and Mg(OH)2 and water gives 1,1-dichloroethylene... 

The principal use of 1,1,2-trichloroethane is as a feedstock intermediate in the production of 1,1-dichloroethylene. 1,1,2-Trichloroethane is also used where its high solvency for chlorinated mbbers, etc, is needed, as a solvent for pharmaceutical preparation, and in the manufacture of electronic components. 

Tetrachloroethane is often an incidental by-product in the manufacture of chlorinated ethanes. It can be prepared by heating the 1,1,2,2-isomer with anhydrous aluminum chloride or chlorination of 1,1-dichloroethylene at 40°C (118). Hydrochlorination of trichloroethylene using a FeCl catalyst may also be used. 

Dichloroethane, see Ethylene dichloride 1,1 -Dichloroethylene, see Vinylidene chloride ... 

Chemical Designations - Synonyms 1,1-Dichloroethylene, unsym-Dichloroethylene Chemical Formula CHj=CClj. 

Up to this point we ve discussed only homopolymers—polymers that are made up of identical repeating units, in practice, however, copolymers are more important commercially. Copolymers are obtained when two or more different monomers are allowed to polymerize together. For example, copolymerization of vinyl chloride with vinylidene chloride (1,1-dichloroethylene) in a 1 4 ratio leads to the polymer Saran. 

The Dependence of Bond Angles on Single Bond-Double Bond Resonance.—In a molecule such as phosgene or 1,1-dichloroethylene the value 125°16 for the angle Cl-C-0 (0) is predicted by the theory of the tetrahedral carbon atom in case that the C-Cl bonds have no double bond character. If the double bond resonates equally among all three positions, giving the Cl-C bond one-third double bond character, we expect from symmetry... 

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