Vinyl acetate vapor

Activated Charcoal. The original intent of the research was to develop a sampling technique that used coconut-shell charcoal to collect vinyl acetate vapors from air samples. Therefore, the breakthrough volume and desorption efficiency of vinyl acetate on coconut-shell charcoal were studied. 

The samples were gradually heated to 300°C while desorption products were pumped out through a liquid nitrogen cooled trap. The ratio of isomers was evaluated by Hl-N.M.R. Mass spectra included very weak signals at m/e 60 and 61 which were tentatively identified with HOAc arid DOAc, respectively. A control experiment established that no detectable amount of cis-trans isomerization occurred when vinyl acetate vapor was exposed to the same conditions in the absence of the carbon sample. 

Morrison, ," Acetylene still has benefits for malting vinyl acetate", Oil and GasJ.[Memot S) 104-116(1969). Vinyl acetate. Vapor phase process. Bntish Chem. Engng, Process SCAN (May 1970). 

The crude vinyl acetate vapor emerging from the catalyzer passes through the heat exchanger and then to a separator where carbon dust is removed. The vapor is then passed through a series of three condensers, as is illustrated in the flow diagram (Fig. 12-10) Condensate from each of... 

Selective Measurement of Vinyl Acetate Vapor Using a Coated Surface Acoustic Wave Oscillator... 

A coated surface-acoustic-wave (SAW) sensor capable of real-time, selective measurement of vinyl acetate vapor in the presence of several olefin and non-olefin cocontaminants is described. The coating film en loyed consists of the solid platinum-ethylene Ji-complex, trans-PtCl (ethylene)(pyridine). occluded in a polyisobutylene matrix. Exposure to vinyl acetate results in displacement of ethylene from the cott lex and formation of the vinyl acetate-substituted complex. Subsequent regeneration of the original reagent is possible by treatment with ethylene gas, in situ. A lower detection limit of 5 ppm of vinyl acetate is achieved for operation at 46 C. The industrial-hygiene applications of the sensor are discussed. 

Precaution Incompat. with HF, oxygen difluoride, chlorine trifluoride may react vigorously with vinyl acetate vapor wear safety glasses, approved respirator, gloves, and lab coat... 

Acetylation of acetaldehyde to ethyUdene diacetate [542-10-9], a precursor of vinyl acetate, has long been known (7), but the condensation of formaldehyde [50-00-0] and acetic acid vapors to furnish acryflc acid [97-10-7] is more recent (30). These reactions consume relatively more energy than other routes for manufacturing vinyl acetate or acryflc acid, and thus are not likely to be further developed. Vapor-phase methanol—methyl acetate oxidation using simultaneous condensation to yield methyl acrylate is still being developed (28). A vanadium—titania phosphate catalyst is employed in that process. 

Liquid- and vapor-phase processes have been described the latter appear to be advantageous. Supported cadmium, zinc, or mercury salts are used as catalysts. In 1963 it was estimated that 85% of U.S. vinyl acetate capacity was based on acetylene, but it has been completely replaced since about 1982 by newer technology using oxidative addition of acetic acid to ethylene (2) (see Vinyl polymers). In western Europe production of vinyl acetate from acetylene stiU remains a significant commercial route. 

Ethylene vinyl acetate copolymer (EVA) forms a soft, tacky film with good water-vapor barrier but very poor gas-barrier properties. It is widely used as a low temperature initiation and broad-range, heat-sealing medium. The film also serves for lamination to other substrates for heat-sealing purposes. 

Vinyl ethers are prepared in a solution process at 150—200°C with alkaH metal hydroxide catalysts (32—34), although a vapor-phase process has been reported (35). A wide variety of vinyl ethers are produced commercially. Vinyl acetate has been manufactured from acetic acid and acetylene in a vapor-phase process using zinc acetate catalyst (36,37), but ethylene is the currently preferred raw material. Vinyl derivatives of amines, amides, and mercaptans can be made similarly. A/-Vinyl-2-pyrroHdinone is a commercially important monomer prepared by vinylation of 2-pyrroHdinone using a base catalyst. 

Vinyl acetate (ethenyl acetate) is produced in the vapor-phase reaction at 180—200°C of acetylene and acetic acid over a cadmium, 2inc, or mercury acetate catalyst. However, the palladium-cataly2ed reaction of ethylene and acetic acid has displaced most of the commercial acetylene-based units (see Acetylene-DERIVED chemicals Vinyl polymers). Current production is dependent on the use of low cost by-product acetylene from ethylene plants or from low cost hydrocarbon feeds. 

Vinyl acetate is a colorless, flammable Hquid having an initially pleasant odor which quickly becomes sharp and irritating. Table 1 Hsts the physical properties of the monomer. Information on properties, safety, and handling of vinyl acetate has been pubUshed (5—9). The vapor pressure, heat of vaporization, vapor heat capacity, Hquid heat capacity, Hquid density, vapor viscosity, Hquid viscosity, surface tension, vapor thermal conductivity, and Hquid thermal conductivity profile over temperature ranges have also been pubHshed (10). Table 2 (11) Hsts the solubiHty information for vinyl acetate. Unlike monomers such as styrene, vinyl acetate has a significant level of solubiHty in water which contributes to unique polymerization behavior. Vinyl acetate forms azeotropic mixtures (Table 3) (12). 

Other large-volume esters are vinyl acetate [108-05-4] (VAM, 1.15 x 10 t/yr), methyl methacrylate [80-62-6] (MMA, 0.54 x 10 t/yr), and dioctyl phthalate [117-81-7] (DOP, 0.14 x 10 t/yr). VAM (see Vinyl polymers) is produced for the most part by the vapor-phase oxidative acetoxylation of ethylene. MMA (see Methacrylic polymers) and DOP (see Phthalic acids) are produced by direct esterification techniques involving methacryHc acid and phthaHc anhydride, respectively. 

Most of the vinyl acetate produced in the United States is made by the vapor-phase ethylene process. In this process, a vapor-phase mixture of ethylene, acetic acid, and oxygen is passed at elevated temperature and pressures over a fixed-bed catalyst consisting of supported palladium (85). Less than 70% oxygen, acetic acid, and ethylene conversion is realized per pass. Therefore, these components have to be recovered and returned to the reaction zone. The vinyl acetate yield using this process is typically in the 91—95% range (86). Vinyl acetate can be manufactured also from acetylene, acetaldehyde, and the hquid-phase ethylene process (see Vinyl polymers). 

Vinyl acetate is made from ethylene, oxygen, and acetic acid in the vapor phase at 150 to 175°C (302 to 347°F) with supported Pd catalyst in packed tubes, 25 mm (0.082 ft) ID. 

Like vinyl acetate from ethylene, allyl acetate is produced by the vapor-phase oxyacylation of propylene. The catalyzed reaction occurs at approximately 180°C and 4 atmospheres over a Pd/KOAc catalyst ... 

VDC polymerization and, 25 696 water-vapor transmission rate, 3 387t PolyCvinyl chloride) cable, 77 848 PolyCvinyl chloride-co-vinyl acetate), 7 524 Poly(vinyl chloride) polymers, lead phosphite in, 14 791... 

Resa, J.M., Gonzalez, C., de Eandaluce, S.O., andLanz, J. Vapor-liquid equilibrium of binary mixtures containing methanol + propyl acetate, methanol + isopropyl acetate, vinyl acetate + propyl acetate, and vinyl acetate + isopropyl acetate at 101.3... 

Prolonged dermal contact, such as that afforded by clothing wet with vinyl acetate, may result in severe irritation or blistering of the skin in some persons. Direct eye contact with the liquid or vapor can cause irritation of the eyes. ... 

In 1969, 90% of vinyl acetate was manufactured by this process. By 1975 only 10% was made from acetylene, and in 1980 it was obsolete. Instead, a newer method based on ethylene replaced this old acetylene chemistry. A Wacker catalyst is used in this process similar to that for acetic acid. Since the acetic acid can also be made from ethylene, the basic raw material is solely ethylene, in recent years very economically advantageous as compared to acetylene chemistry. An older liquid-phase process has been replaced by a vapor-phase reaction run at 70-140 psi and 175-200°C. Catalysts may be (1) C—PdCb—CuCb, (2) PdClj—AI2O3, or (3) Pd—C, KOAc. The product is distilled water, acetaldehyde, and some polymer are... 

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