Document 3QX1vO8n3n3JZKG97o0Y9ywkD
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CHLOROCARBONS AND CIILOROIIYDROCARBONS
171
Uric VINYL CHLORIDE
Vinyl chloride (chloroothylcnc, monochlorocthyhme), CH^=CHC1, at ordinary
temperature and normal pressure, is a colorless gas with an irritant action on the
eyes and an odor reminiscent of that of ethyl chloride. Industrially, vinyl chloride is
handled as the liquid (bp, -- 13.9C). To prevent its polymerization during storage ben- or transport, stabilizers may be added. It is readily flammable, has a voiy low flash
point, and forms explosive mixtures with air. Vinyl chloride is veiy slightly soluble
in water, and soluble in most of the common industrial solvents. Its toxicity is less
than that of carbon tetrachloride or chloroform, and it has a narcotic effect similar to ucal that of ethyl chloride. By far, the most important use of vinyl chloride is hi the
manufacture of polyvinyl chloride (PVC) and related plastics. It is used to a small
extent as a special solvent, a refrigerant, and in chemical synthesis.
Vinyl chloride was first prepared and described by Regnault, in 1835. He ob
tained it by reacting dichloroethanc with alcoholic potash* Regnault observed that M9, on prolonged exposure to sunlight in a sealed tube the liquid deposited white flakes
of solid. In the state of organic chemical theory and knowledge at that date, he
could only record, without explanation, this liquid-to-solid change, llcgnault's white
solid was studied in 1872 by Baumann without its nature being fully elucidated; he
described the material as "Kauprenchlorid" and gave it the empirical formula (C*-
H3Cl)a. In 1911, IQatte and Rollett investigated the reaction between hydrogen
chloride and acetylene, and two years later, Grieshcim-Elektron obtained a patent for
the use of mercuric chloride as a catalyst in tins reaction, thus establishing an effective
industrial route to vinyl chloride.
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The low price and ready availability of natural rubber and absence of technical
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I interest in the type of plastic product produced from vinyl chloride limited develop
m. ment of vinyl chloride manufacture prior to the outbreak of World War II. When
that war cut off the Western powers from their natural rubber sources, production of
vinyl chloride for PVC, as a rubber substitute, was established on a large scale in the
United States and the United Kingdom. Vinyl chloride is now one of the most
important starting materials of the plastics industry.
Physical and Chemical Properties
>urs The physical properties of vinyl chloride arc given in Tabic 1. At 25C, 0.11 g vinyl chloride dissolves in 100 g water, and at -- 15C, 0.03 g
water dissolves in 100 g vinyl chloride. Vinyl chloride is soluble in mineral oil, alcohol, the industrial chlorinated solvents, and a number of common organic liquids. No azeotropes have been reported.
Reactions. In its chemical behavior, vinyl chloride obeys the general rule that the simple unsaluratcd chlorohydrocarbons are more stable than saturated ones. At Co. about 450C, vinyl chloride begins to decompose, forming small amounts of acetylene (2). In the presence of a copper, lead, tin, or cadmium catalyst, at 400G, vinyl chloride forms 2-cliloro-l,3-butadienc (3). When vinyl chloride is dry, no decom position takes place in contact with metals at temperatures below those just indicated. Wet vinyl chloride, at elevated temperature, corrodes iron and stool. The thermal 1 .Id. and photochemical decompositions of vinyl chloride, in contact with air, do not appear to liavo been systematically studied. The decomposition products (peroxygen coin-
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172 CI1LOROCAUBONS ANJ) CHLOItOHYDUOCAUBONS
Tabic 1, Physical Properties <>f Vinyl Chloride
melting point, C boiling puint, 700 mm Ilg, C specific gravity
J3.0/4C 20/4C nlf surface tension, air, clyn/cm -- 30C --20C -I0C specific heat, cnl/(KXC) liquid, 20O vapor, 25C critical temperature, critical pressure, atm dielectric constant, 17.2 C heat of combuation, 18C, constant pressure, teal/g-mole
latent heat of evaporation, eal/g
bp 25C latent heat of fusion, cal/g flash point open cup, P closed cup, C self-ignition temperature, C explosive limits in air, % by vol viscosity, liquid, eP --40C --30C --20C -10C vapor pressure
c
-30 -20 -10
0 10 -
atm
0.50 0.77 1.17 1.70 2.43
The most readily ignitablc mixture is that containing 7% vinyl chloride (1).
-153.7 --13.9
0.94 0.9121 1.4010
23.87 22.27 20.88
0.38 0.205 158.4 52.7 6.26 286.16
79.53 71.26 13.14
-108 -78 472 4-20
0.3339 0.3026 0.2780 0.2563 C aim 20 3.33 30 4.51 40 5.94 50 7.80 60 9.93
pounds) bring about polymerization, thus obscuring their -intermediate presence,
and hindering their quantitative study.
I
With chlorine, vinyl chloride forms 1,1,2-trichlorocthano (see p. 158), and with
j
bromine, l-chloro-l,2-dibromoethane (4). In the presence of zinc chloride on silica
j
gel, hydrogen chloride combines with vinyl chloride, at about 100Q, to give 1,1-
\
dichloroethane (sec p. 149); at room temperature and in absence of catalysts, hydrogen
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iodide, in similar fashion, forms l-chloro-I-iodoethane. Sulfuryl chloride (SO2CI2),
in the presence of pyridine, reacts with vinyl chloride, at ordinary temperature, to
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give 1,1,2-triehloroethane and 2,2-dichlomcthanc sulfonyl chloride. Ilypochlorous
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acid and vinyl chloride react to yield chloroaeetaldehyde, OlCIIjCII--O (5,6).
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In the presence of anhydrous aluminum chloride, vinyl chloride condenses with
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ethyl chloride, at 50C, yielding the products, 1.1-diehloroethane and 1,1,3-tvichloro- *
i butane (7). At 0-5C, vinyl chloride reacts with benzene, in the presence of aluminum i
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176 C11LOKOCAUBONS AND CULOKOI1YDUOCAUBONS
Other Processes. Production of vinyl chloride by pyrolysis of ethylidone chlo ride, GlljCHClj, followed by reaction of the coproduct hydrogen chloride with acet ylene, has been patented (3G). Vinyl chloride is produced by treatment of 1,1,2Inehloroethauc, at high temperatures, with finely divided zinc, iron, or aluminum in the presence of steam (37).
Economic Aspects
In Table 2 are listed annual outputs and sales of vinyl chloride in the U.S. for the period 1935-1902. These reilect the great and growing importance of polyvinyl chloride plastic. Other producing countries, including the "United Kingdom, do not publish statistics of their vinyl chloride outputs. An indication of the scale of produc tion in France is given by the French government's published plan to make 104,000 metric tons in 19U0. Reports indicate a considerable international trade in vinyl chloride between the countries of the European Economic Community.
Tabic 2. U.S. Vinyl Chloride Production and Price Statistics8
Sales
Year
FrcMlucliun, Eb6
Quantity, lb6
Total value, $e Unit value, $/lb
1955 1956 1957 1958 1959 I960 1961 1962
528,605 596,520 627,076 691,412 977,891 1,036,989 1,043,983 1,311,489
76,002 103,878 179,756 200,488 329,360 352,314 424,303 515,522
7,935 11,133 19,561 22,161 35,817 35,804 34,229 38,548
0.10 0.11 0.11 0.11 0.11 0 10 0.08 0.07
<* According to U .S . Tariff Commission Reports. 6 In thousands of pounds. e In thousands of dollars.
Standards
Technical-grade vinyl chloride should not eontaiii more than -the following amounts of the indicated impurities: acetylene, 1 ppm; aldehyde (as acetaldehyde), 100 ppm; acid (as IICl), 0-1 ppm; water, 100 ppm; residue on evaporation to dryness, 10 ppm. Acetaldehyde is nonexistent in vinyl chloride produced by cracking dichloroethanc.
Handling and Toxicity
When vinyl chloride is to ho stored or transported, phenolic or other type stabilizers arc sometimes added to prevent its polymerization. In small quantities, vinyl ehlorido is transported as the liquid, under pnsssure, in steel cylinders or drums. Hulk deliveries are made in road tank trucks. Vinyl chloride is transferred from tank trucks to storage vessels by pumping or blowing, sometimes under a nitrogen atmosphere. A thin layer of polymer may gradually form on the walls of steel storage vessels and pipes in the plant when using vinyl chloride; however, with the dry, pure product this does not occur. Copper or copper-alloy fittings should not he used, because of the possibility of explosive acolylido formation with residual aectylc.no in the vinyl clilo-
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ride. Leakages from stor,me vessels or elsewhere in the plant are located by means of snap solution; because; of the high flammability of vinyl chloride and its formation of explosive mixtures with air, a halide lamp must never be used for its detection.
Vinyl chloride is considerably less toxic than either carbon tetrachloride or cldoroform and is similar in toxicity to ethyl chloride. At concentrations, in air, of 20-40% (by vol), it is rapidly fatal to small test mammals. It exerts a narcotic action similar to that of ethyl chloride. At concentrations of 5% (by vol), vinyl chloride gives warning of its presence by causing dizziness and disorientation. Concentra tion in the atmosphere of working spaces should never exceed .rQ0 ppm (by vol). 3rhere-is no evidenee-of. direct, .iniur-y-Inwing-Feeulted-fiour-prolonged-exposure-to fconcentrations-oHhatrerder
Uses
Vinyl chloride would have attained little importance as an industrial chemical had it not been capable of polymerizing and copolymcrizing to materials which form one of the most important groups of modern plastics. This use is dealt with under Vinyl compounds, resins, and plastics. The remaining applications of the compound are quantitatively insignificant.
In the pliaramaceutical industry, vinyl chloride is used in the production of chloroacetaldchyde, an intermediate in the manufacture of the sulfa drugs.
Conversion of vinyl chloride to 2-chioro-l,3-butadienc, the intermediate in the production of chloroprenc rubber, has been patented (38).
Vinyl chloride has been used as a refrigerant and as an extraction solvent for heat-sensitive substances. Its use in those and similar applications, eg, as an aerosol propellant, is generally undesirable because of its flammability, toxicity, and readiness to polymerize.
Bibliography
'`Vinyl Chloride" under "Chlorine Compounds, Organic" in EC')' 1st cd., Vol. 3, p. 7SO by Jesse Werner, General Aniline & Film Corp., General Aniline Works Division; "Vinyl Chloride'' under "Vinyl Compounds" in ECT 1st ed., Vol. 14, pp. 723-726, by Claude H. Alexander and Gerald F. Cohan, B.F. Goodrich Chemical Company.
1. S. K. Shaw, Bril. Elect. lies. Assoc. Report GfT 877. 2. D. H. R. Barton and K. E. Ilowlett, J. Ckem. Soc. 1949,160. 3. U.S. Pat. 1,884,002 (Oct. 25, 1052), C. J. Leyes. 4. H. Bills, Her. Deni. Chem. Gc*. 35, 3525 (1902). 5. Ger. Pat. 406,002 (Oct. 23, 1927), 0. Ernst and II. Lango (to I. (_< Farbemndnslrio A.G.). 0. U.S. Pat. 2,000,303 (Nov. 10, 1036), H. P. A. Groll and G. Ileame. 7. L, Sc-hmcrling, J. Am. Chau. Soc. 68, 1653 (1016). S. J. M. Davidson and A. Lmvy, J. Am. Chcm. Soc. 51,2079 (1920). 0. llrit. Pat. 405,4(17 (Nov. 2, 1935), I. G. Farbeniiidustrie A.C1. b 10. Brit. Pat. 332.G05 (Aug. 21, 1930), I. G. Farbenindustric A.G. s 11. Can. Pat. 447,930 (Apvil 20, 19-18), W. A. Lazier aftd O. M. Whitman (to Canadian Industries o Ltd.). \ 12. Brit. Pat. 611,015 (Oct. 5, 1945), SnlvayA Cd. 13. U.S. Pat. 2,015,054 (Oct. 21, 1052), II. k Miller (In Air Reduction G>.). d 14. U.S. Put. 2,4-16,128 (July 7, 1!MS), T. Boyd (to Monsanto Chemical Co.). is 15. U.S. Pat. 2,-IIS, 110 (Aug. 31, 194X)', U.S. Miller (to Air Koduclinn Co.). 1C 1G. Brit. Pat. 695,105 (March ), 1950), M. Arlonbeuh and A. Kirghiz. 17. Can. Put. 48S.723 (Dec, 0, 1952), W. B. Morgan (to B. F. Goodrich & Co.).
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