Vinyl chloride

Structural formula
General
Surname	Vinyl chloride
other names	Chloroethene Chlorethylene (obsolete) Monochloroethene ("overdetermined") Monochlorethylene (obsolete) R-1140 Frigen 1140 (coolant industry)
Molecular formula	C 2 H 3 Cl
Brief description	colorless and odorless gas
External identifiers / databases
CAS number 75-01-4 EC number 200-831-0 ECHA InfoCard 100,000,756 PubChem 6338 Wikidata Q338869
properties
Molar mass	62.5 g mol −1
Physical state	gaseous
density	2.86 kg m −3 (0 ° C and 1.013 bar)
Melting point	−153.7 ° C
boiling point	−13.4 ° C
Vapor pressure	0.33 M Pa (20 ° C)
solubility	1.1 g l −1 in water at 20 ° C good in ethanol and diethyl ether
Dipole moment	1.45 D (4.8 x 10 -30  C  ·  m )
Refractive index	1.3700 (20 ° C)
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 280-220-350 P: 202-210-281-308 + 313-377-403
MAK	DFG : no information, as carcinogenic Switzerland: 1 ml m −3 or 2.6 mg m −3
Toxicological data	500 mg kg −1 ( LD 50 ,  rat ,  oral )
Thermodynamic properties
ΔH f 0	37.2 kJ / mol
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Vinyl chloride ( chloroethene , also monochloroethene or - actually outdated - monochloroethylene ), abbreviated to VC , is a colorless, flammable, narcotic gas with a slightly sweet, chlorine- like odor in high concentrations . It is the basic substance for the production of polyvinyl chloride (PVC). Vinyl chloride was discovered by Henri Victor Regnault .

Extraction and presentation

Historical procedure

The first process for the technical production of vinyl chloride was developed by the chemical factory Griesheim-Elektron . Thereafter, acetylene with hydrogen chloride in a hydrochlorination at temperatures of 140-200 ° C at normal pressure, mercury (II) chloride - catalysts which on charcoal reacted are supported.

The entire reaction takes place in the gas phase and is carried out in tube bundle reactors , which cool the exothermic reaction (ΔH _R = –98.8 kJ · mol ⁻¹ ) with the aid of an oil circuit. The acetylene conversion is almost quantitative at 96-97% and the vinyl chloride selectivity is 98-99%. The process is generally very selective and requires little equipment.

The use of acetylene as a raw material for industrial vinyl chloride production has lost a lot of its importance in the last few decades. The high cost of acetylene in contrast to cheaper and more readily available raw materials based on petrochemical production , especially ethene , meant that by the turn of the millennium only 5% of vinyl chloride was still produced on the basis of acetylene.

In the last few years the situation has changed again significantly. Today, almost 23% of vinyl chloride is again made from acetylene. This can be explained by the fact that the current synthesis of vinyl chloride based on acetylene (often also in processes coupled with the EDC route), especially in regions where acetylene is still available inexpensively as a raw material and can also be extracted cheaply ) he follows. This process is still profitable, especially in China and South Africa - both areas that still have large coal and rock salt deposits and low additional costs (e.g. electricity).

Modern procedures

In the modern production of vinyl chloride, the first step is to produce 1,2-dichloroethane from ethene and chlorine by so-called "direct chlorination" .

Δ H  = −180 kJ / mol

The representation by means of oxychlorination of ethene with hydrogen chloride and oxygen is also widespread .

Δ H  = −239 kJ / mol

In a subsequent step, the 1,2-dichloroethane is converted to vinyl chloride with elimination of hydrogen chloride.

Δ H  = +71 kJ / mol

In 2010, around 35 million tons of vinyl chloride were used worldwide.

properties

Vinyl chloride is easily flammable (ignition temperature 435 ° C). With a volume fraction of 3.8 to 31 percent in air, it is explosive. Vinyl chloride condenses at −13.9 ° C and solidifies at −154 ° C.

Vinyl chloride polymerizes to polyvinyl chloride when exposed to light, air and heat . Burning vinyl chloride produces hydrogen chloride and traces of phosgene . Vinyl chloride dissolves almost indefinitely in organic solvents, but only slightly in water . The heat of polymerization is −71 kJ mol ⁻¹ or −1135 kJ kg ⁻¹ .

use

The main use of vinyl chloride is to make polyvinyl chloride (around 38 million tons in 2004). This is done by means of radical polymerisation . In the past, vinyl chloride was also used as a coolant under various names.

environment

In its Air Quality Guidelines for Europe , the WHO assumes that the average air concentration generally present in Western European countries is between 0.1 and 0.5 μg / m ³ . In the vicinity of vinyl chloride and polyvinyl chloride systems, the 24-hour concentrations can exceed 100 μg / m ³ . At distances of over one kilometer from the system, they are usually below 10 μg / m ³ . VC decomposes in air and has a half-life of 20 hours. The WHO assumes that with a lifetime exposure to 1 μg / m ³ the cancer risk is 1 in 1 million.

In 1974 in the Federal Republic of Germany the emission of vinyl chloride during the production of PVC was between 15 and 55 kg per tonne of PVC produced, but two years later it was reduced to values ​​between 8 and 20 kg per tonne of PVC produced.

safety instructions

For a long time, vinyl chloride was only classified as narcotic and irritating to the eyes. The toxic properties to humans were first recognized in the 1960s. It was not until the early 1970s that the clinical picture of vinyl chloride disease was recognized. The liver , esophagus and spleen, as well as the blood flow to the hand, hand bones and skin are affected.

Exposure to vinyl chloride has been described etiopathogenetically as the cause of idiopathic acroosteolysis (Black-Nail syndrome) and Raynaud's syndrome .

Hans Popper (1903–1988) made the important observation that occupational exposure to vinyl chloride is hepatotoxic and often leads to the occurrence of hepatic angiosarcoma . It has been classified as carcinogenic and can cause hemangioendothelial sarcomas of the liver , for example .

The limit values ​​for the maximum vinyl chloride concentration at the workplace were continuously reduced: in 1966 the MAK value was 500  ppm , in 1971 100 ppm and 1974 50 ppm. Due to the carcinogenicity that has now been proven , no MAK limit value can be established today.

Respiratory protection and full protection are necessary as protective measures during handling. The storage takes place in pressure cans and cylinders.

Dismantling

Thiodiglycolic acid can be detected in urine as a metabolite of vinyl chloride.

More information

The binding occupational exposure limit for vinyl chloride in the European Union is 3 ppm or 7.77 mg · m ⁻³ (2004/37 / EC). An occupational exposure limit according to TRGS 900 is currently not specified for vinyl chloride in Germany. However, vinyl chloride is on the processing list of the Committee for Hazardous Substances (as of September 2014) with the aim of proposing an occupational exposure limit for inclusion in TRGS 900 or deriving an exposure-risk relationship (ERB) according to TRGS 910. Vinyl chloride is classified as a category K1 carcinogen (substances known to be carcinogenic in humans).

Individual evidence

1. ↑ ^{a b c d e f g h i j k} Entry on vinyl chloride in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
2. ↑ Entry on vinyl chloride. In: Römpp Online . Georg Thieme Verlag, accessed on October 1, 2014.
3. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Permittivity (Dielectric Constant) of Gases, pp. 6-188.
4. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-100.
5. ↑ Entry on chloroethylene in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
6. ↑ Swiss Accident Insurance Fund (Suva): Limits - Current MAK and BAT values (search for 75-01-4 or vinyl chloride (monomer) ), accessed on September 14, 2019.
7. ↑ Data sheet Vinyl chloride from Sigma-Aldrich , accessed on April 25, 2011 ( PDF ).
8. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-21.
9. ↑ ^{a b c} Hans-Jürgen Arpe: Industrial organic chemistry - important preliminary and intermediate products . 6th edition. WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 2007, ISBN 978-3-527-31540-6 , p. 238 f .
10. ↑ Manfred Fedtke, Wilhelm Pritzkow, Gerhard Zimmermann: Technical organic chemistry - basic materials, intermediate products, final products, polymers . 1st edition. Deutscher Verlag für Grundstoffindustrie GmbH, Leipzig 1992, ISBN 3-342-00420-7 , p. 99 .
11. ↑ Manfred Baerns, Arno Behr, Axel Brehm, Jürgen Gmehling, Kai-Olaf Hinrichsen, Hanns Hofmann, Regina Palkovits, Ulfert Onken, Albert Renken: Technische Chemie . 2nd Edition. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany 2013, ISBN 978-3-527-33072-0 , p. 614 .
12. ↑ Chemical technology - processes and products . In: Roland Dittmeyer, Wilhelm Keim, Gerhard Kreysa, Alfred Oberholz (eds.): Winnacker Küchler . 5th edition. tape 5 . Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany 2005, ISBN 978-3-527-30770-8 , pp. 27 .
13. ^ ^{A b c} Hans-Jürgen Arpe: Industrial organic chemistry . 6th edition. Wiley-VCH, Weinheim 2007, ISBN 978-3-527-31540-6 , pp. 237-245 .
14. ↑ Joachim Buddrus: Fundamentals of organic chemistry. Walter de Gruyter Verlag, Berlin, 4th edition, 2011, ISBN 978-3-11-024894-4 , p. 252.
15. ↑ Trade Association Raw Materials and Chemical Industry , Leaflet R 008 Polyreactions and Polymerizable Systems , Edition 05/2015, ISBN 978-3-86825-069-5 .
16. ↑ Lecture with production figures for various plastics (PDF; 3.3 MB).
17. ^ Entry on vinyl chloride in the ChemSpider database of the Royal Society of Chemistry , accessed on January 22, 2014.
18. ↑ Air Quality Guidelines for Europe (PDF; 1.1 MB), 2nd Ed, 2000.
19. ^ Fritz Vahrenholt : The development of vinyl chloride emission in PVC production. In: Dust - cleanliness. Air . 37, No. 11, 1977, pp. 416-417.
20. ^ Rudi Schmid, Hans Popper , National Academy of Sciences, 1994. accessed on February 14, 2020.
21. ↑ W. Hiddemann: Medicine in focus. Springer-Verlag, 2013, ISBN 978-3-642-59730-5 , p. 479 ( limited preview in Google book search).
22. ↑ Binding occupational exposure limits of the EU Commission Institute for Occupational Safety and Health of the German Social Accident Insurance, accessed June 29, 2015
23. ↑ Working list of the AGS BAuA, accessed June 29, 2015, (PDF).