Ethylene oxide precautions

An explosion and fire (March 13, 1991) occurred at an ethylene oxide unit at Union Carbide Chemicals Plastics Co. s Seadrift plant in Port Lavaca, TX, 125 miles southwest of Houston. The blast killed one, injured 19, and idled the facility, that also produces ethylene, ethylene glycol, glycol ether ethanolamines, and polyethylene. Twenty-five residents were evacuated for several hours as a safety precaution. The plant lost all electrical power, for a few days, because its cogeneration unit was damaged. The Seadrift plant, with 1,600 workers, is capable of making 820 million lb per year of ethylene oxide which is one-third of Carbide s worldwide production of antifreeze, polyester fibers, and surfactants Seadrift produces two thirds of Carbide s worldwide production of polyethylene. 

Despite these precautions, an explosion occurred. One day, when ethylene oxide addition was started, the pressure in the reactor rose. This showed that the ethylene oxide was not reacting. The operator decided that perhaps the temperature point was reading low or perhaps a bit more heat was required to start the reaction, so he adjusted the trip setting and allowed the indicated temperature to rise to 200°C. Still the pressure did not fall. 

Freeder, B. G. et al., J. Loss Prev. Process Ind., 1988, 1, 164-168 Accidental contamination of a 90 kg cylinder of ethylene oxide with a little sodium hydroxide solution led to explosive failure of the cylinder over 8 hours later [1], Based on later studies of the kinetics and heat release of the poly condensation reaction, it was estimated that after 8 hours and 1 min, some 12.7% of the oxide had condensed with an increase in temperature from 20 to 100°C. At this point the heat release rate was calculated to be 2.1 MJ/min, and 100 s later the temperature and heat release rate would be 160° and 1.67 MJ/s respectively, with 28% condensation. Complete reaction would have been attained some 16 s later at a temperature of 700°C [2], Precautions designed to prevent explosive polymerisation of ethylene oxide are discussed, including rigid exclusion of acids covalent halides, such as aluminium chloride, iron(III) chloride, tin(IV) chloride basic materials like alkali hydroxides, ammonia, amines, metallic potassium and catalytically active solids such as aluminium oxide, iron oxide, or rust [1] A comparative study of the runaway exothermic polymerisation of ethylene oxide and of propylene oxide by 10 wt% of solutions of sodium hydroxide of various concentrations has been done using ARC. Results below show onset temperatures/corrected adiabatic exotherm/maximum pressure attained and heat of polymerisation for the least (0.125 M) and most (1 M) concentrated alkali solutions used as catalysts. 

Of equal importance with these two reactions, but unfortunately much less clear, is the mechanism of oxonium ion formation since it will determine the importance of these intermediates in the polymerizations. The scheme proposed by Meerwein and described above was based entirely on careful product analysis of reactions carried out without extreme precautions to exclude moisture. While it seems reasonable enough, it may require modification as more information becomes available. The question of the role of water in the formation may perhaps be an academic one in the case of the epoxides because even rigorously dry ethylene oxide appears to react with boron fluoride at — 80° (4) to form compounds of the type... 

The addition of a gas to a reaction mixture (commonly the hydrogen halides, fluorine, chlorine, phosgene, boron trifluoride, carbon dioxide, ammonia, gaseous unsaturated hydrocarbons, ethylene oxide) requires the provision of safety precautions which may not be immediately apparent. Some of these gases may be generated in situ (e.g. diborane in hydroboration reactions), some may be commercially available in cylinders, and some may be generated by chemical or other means (e.g. carbon dioxide, ozone). An individual description of the convenient sources of these gases will be found under Section 4.2. 

The reagent has b.p. 11 °C and is supplied either in 100-ml sealed tubes or in 100-ml cylinders equipped with an appropriate valve. The gas, which is highly flammable, has no very distinctive smell and must be regarded as a hazardous toxic reagent which must not be inhaled or allowed to come into contact with the skin and eyes. Precautions in the use of ethylene oxide are described in Expt 5.39, which may be regarded as typical. 

The first set of reactions is the mainstay of the petrochemical industry 1 outstanding examples are the oxidation of propene to propenal (acrolein) catalysed by bismuth molybdate, and of ethene to oxirane (ethylene oxide) catalysed by silver. In general these processes work at high but not perfect selectivity, the catalysts having been fine-tuned by inclusion of promoters to secure optimum performance. An especially important reaction is the oxidation of ethene in the presence of acetic (ethanoic) acid to form vinyl acetate (ethenyl ethanoate) catalysed by supported palladium-gold catalysts this is treated in Section 8.4. Oxidation reactions are very exothermic, and special precautions have to be taken to avoid the catalyst over-heating. 

What safety precautions should you take with the ethylene oxide format tion discussed in Example 4-6 With the bromine cyanide discussed in Example 4-11 ... 

Pests, once estabUshed, are extremely difficult to eradicate and prevention is easier and less expensive than the total sacrifice of the contaminated product. Apart from the commonsense hygiene precautions, many commercial firms use a variety of techniques to eradicate insects in stored crude drugs. None of the methods presently available are ideal dry or moist heat may damage the constituents fumigation with hydrogen cyanide or methylbromide may cause toxicity, while the commonly used ethylene oxide has been banned by the EU because of the suspected carcinogenicity of the chlorohydrin formed from the gas. Some companies use irradiation. Many studies have been conducted on the effects of this controversial method on the constituents of medicinal plants. Most reported studies show no effect on chemical content, with the exception of opium where... 

What should you do if some of the ethylene glycol spla.shed out of reactor onto your face and clothing itiinr. Recall ivnH. stVi.nrg/.) What safety precautions should you take with the ethylene oxide forn tion discussed in Example 4-6 With the bromine cyanide discussed E.xampie 4-9 ... 

Although various gases can be employed, e.g. formaldehyde, ethylene oxide, most pharmaceutical processes relate to the latter. Since ethylene oxide (and its residues) are toxic and it forms explosive mixtures with air/oxygen, special precautions are essential to safe handling. Ethylene oxide is therefore mixed with an inert gas (usually C02) and needs a certain temperature (usually 55°C) and the presence of moisture to be effective, together with materials which are either porous (paper, Tyvek, board) or permeable to the gas (PVC, PS, PE, etc.). This means that there is a solubility or retention factor related to their use and a period must be allowed to reduce residues (by degassing). 

Ethylene oxide is a low boiling, flammable liquid, whose vapors easily form explosive mixtures in air [1]. It is to be labeled as a cancer hazard and a reproductive hazard [2]. It is prudent to handle propylene oxide and other three-membered ring organic oxides with safety precautions similar to those used for ethylene oxide. 

Work should be carried out in well-ventilated hood areas behind safety shields. Full protection against explosive hazard associated with this compoimd is not achieved by this. It also should be kept in mind that the density of ethylene oxide is greater than that of air and therefore, may not necessarily be carried up and out of the hood. Also, the problem of air pollution downwind from the hood s vent needs to be addressed. Special precautions must also be taken for the problems that may arise should there be a release of high levels of ethylene oxide as a result of an explosion. 

Since ethylene oxide is flammable, care must be used in handling it near heating mantles. Reactions that may be carried out under pressure require additional safety precautions. 

Precaution Incompat. with strong oxidizers, reducing agents Hazardous Ingredients Ethylene oxide (< 20 ppm), 1,4-dioxane (< 10 ppm)... 

Toxicology Severe eye irritant, may cause corneal dama mildly irritating to skin ethylene oxide (carcinogenic and reproductive hazard) can accumulate in storage and transport vessels Precaution Incompat. with strong oxidizers Hazardous Ingredients Nonoxynol-40 (70%), ethylene oxide (< 25 ppm), 1,4-dioxane(<20ppm)... 

Properties Almost colorless opaque liq. typ. mild odor sol in most aromatic and aliphatic soivs. disp. in water and min. oil sp.gr. 0.97 g/ml b.p. > 212 F HLB 11.4 cloud pt. 69-73 (10% in 25% bulyl Carbitol) flash pt. (COC) > 300 F pH 5-8 (5% in DV nonionic 100% cone. Toxicology May cause eye and skin irritation ing. may cause nausea, vomiting, and diarrhea inh. may irritate upper respiratory tract ethylene oxide (cancer and reproductive hazard) may accumulate in storage and transport vessels TSCA listed Precaution Incompat. with strong oxidizers Hazardous Ingredients Ethoxylated tridecyl alcohol (100%), ethylene oxide (< 25 ppm), 1,4-dioxane (< 20 ppm)... 

Toxicology May cause skin and eye irritation ing. may cause Gl irritation, nausea, vomiting, and diarrhea TSCA listed Precaution Avoid strong oxidizing agents Hazardous Ingredients Ethylene oxide (trace)... 

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