Vinyl chloride
- Chloroethene
- Chloroethylene (deprecated)
- Monochlorethen ( " overdetermined " )
- Monochloroacetic ethylene (deprecated)
- R1140, freon 1140 (coolant industry)
Colorless and odorless gas
Gaseous
2.86 kg · m -3 ( 0 ° C and 1.013 bar )
-153.7 ° C
-13.4 ° C
0.33 MPa ( 20 ° C)
1.45 D (4.8 · 10-30 C · m)
1.3700 (20 ° C)
Risk
500 mg · kg -1 ( LD50, rat, oral)
37.2 kJ / mol
Template: Infobox chemical / molecular formula search available
Vinyl chloride ( chloroethene also Monochlorethen or - actually outdated - Mono chloroethylene ), abbreviated as VC, is a colorless, combustible, narcotic gas with a slightly sweet odor at high concentrations. It is the basic substance for the preparation of polyvinyl chloride (PVC). Vinyl chloride was discovered by Henri Victor Regnault.
Synthesis
In the manufacture of vinyl chloride, 1,2-dichloroethane, in a first step from ethene and chlorine, by so-called " direct chlorination " is generated.
Another common feature is the presentation by oxychlorination of ethene with hydrogen chloride and oxygen.
In a subsequent step, the 1,2-dichloroethane is reacted by elimination of hydrogen chloride to vinyl chloride.
A further possibility is the addition of hydrogen chloride to ethyne.
Properties
Vinyl chloride is highly flammable (ignition temperature 435 ° C). At a volume fraction from 3.8 to 31 percent in air, it is explosive. Vinyl chloride is condensed at -13.9 ° C and freezes at -154 ° C.
Vinyl chloride is polymerized upon exposure to light, air and heat to polyvinyl chloride. The combustion of the vinyl chloride and hydrogen chloride occur traces of phosgene. Vinyl chloride dissolves almost unlimited in organic solvents, but only slightly in water.
Use
The main purpose of vinyl chloride is the production of polyvinyl chloride ( 2004, about 38 million tons). This is done by means of radical polymerization. Before the vinyl chloride was used under various names as a coolant.
Environment
In their Air Quality Guidelines for Europe, WHO anticipates that the generally existing in Western European countries, average air concentration is between 0.1 and 0.5 ľg/m3. In the neighborhood of vinyl chloride and polyvinyl chloride plants, the 24 -hour concentrations may exceed 100 ľg/m3. At distances of over a kilometer to the system they are usually under 10 ľg/m3. VC decomposes in air and has a half -life of 20 hours. The WHO estimates that in a lifetime exposure to 1 ľg/m3 the risk of cancer is 1 in 1 million.
Safety
Vinyl chloride has been classified a long time merely as numbing and eye irritant. The toxic properties for humans were first detected in the 1960s. It was not until the early 1970s, the clinical picture of vinyl chloride disease has been detected. Liver, esophagus, and the spleen and blood circulation to the hand, the hand bones and skin are affected.
Exposure to vinyl chloride has been described as a cause of idiopathic acro-osteolysis ätiopathologisch (Black nail syndrome ) and Raynaud's syndrome.
Furthermore, it has been classified as a carcinogen and can cause for example Hämangioendothelsarkome the liver.
The limit values for the maximum concentration of vinyl chloride in the workplace have been reduced continuously: 1966 was the TLV 500 ppm, 100 ppm and 1971 ppm 1974 50. Because of the now proven carcinogenicity can now be set no TWA limit.
When handling as protective measures respiratory protection and full protective necessary. They are stored in pressurized cans and cylinders.
Reduction
Thiodiglycolic can be detected as a metabolite of vinyl chloride in the urine.
More information
The Threshold Limit Values according to Technical Rule 900 is at existing plants for VC and PVC production 8 mg · m- 3 and 3 ml · m -3 ( TRK ) and for all other assets 5 mg · m- 3 and 2 ml · m -3 (TRK ). Vinyl chloride is K1 (substances which are carcinogenic in humans known to be ) classified as carcinogenic category.