Peroxides environmental hazards

Common alcohol oxidation methods employ stoichiometric amounts of toxic and reactive oxidants like Cr03, hypervalent iodine reagents (Dess-Martin) and peracids that pose severe safety and environmental hazards in large-scale industrial reactions. Therefore, a variety of catalytic methods for the oxidation of alcohols to aldehydes, ketones or carboxylic acids have been developed employing hydrogen peroxide or alkyl hydroperoxides as stoichiometric oxygen sources in the presence of catalytic amounts of a metal catalyst. The commonly used catalysts for alcohol oxidation are different MoAV(VI), Mn(II), Cr(VI), Re(Vn), Fe(II) and Ru complexes . A selection of published known alcohol oxidations with different catalysts will be presented here. 

Environmental VOC ThOD 1.25 Precaution Combustible exposed to heat or flame LEL 0.8% incompat. with oxidizing materials peroxide former Hazardous Decomp. Prods. Heated to decomp., emits acrid and irritating fumes NFPA Health 1, Flammability 1, Reactivity 0 Uses Solvent for printing inks, water-based... 

Toxicology LD50 (oral, rat) 2400 mg/kg, (skin, rabbit) 1500 mg/kg mod. toxic by ing., skin contact mild skin irritant may cause blood disorders, kidney damage harmful if inhaled or absorbed through skin TSCA listed Environmental VOC ThOD 1.30 Precaution Combustible liq. and vapor peroxide fonner Hazardous Decomp. Prods. CO, COj heated to decomp., emits acrid smoke and irritating fumes... 

As discussed in Section 2.3.3, the mechanism of chloroform-induced liver toxicity may involve metabolism to the reactive intermediate, phosgene, which binds to lipids and proteins of the endoplasmic reticulum, lipid peroxidation, or depletion of GSH by reactive intermediates. Because liver toxicity has been observed in humans exposed to chloroform levels as low as 2 ppm in the workplace and in several animal species after inhalation and oral exposure, it is possible that liver effects could occur in humans exposed to environmental levels, to levels in drinking water, or to levels found at hazardous waste sites. 

Environmental applications require detoxification of hazardous substances to a level of parts per million (ppm) and even parts per billion (ppb). These purity levels, which were rarely considered in product synthesis, are now possible for wastewater due to Fenton s reagent. Fenton s oxidant is cost effective and relatively fast in destroying many toxics (Bigda, 1996). It attacks all reactive substrate concentrations under acidic conditions. Hydrogen peroxide is used to remove such contaminants as cyanide, sulfides, sulfites, chrome, and heavy metals by varying batch conditions. With an iron catalyst, the process often oxidizes organics, as well as reducing hexavalent chrome to trivalent precipitable form. 

Chapter 1 is used to review the history of polyethylene, to survey quintessential features and nomenclatures for this versatile polymer and to introduce transition metal catalysts (the most important catalysts for industrial polyethylene). Free radical polymerization of ethylene and organic peroxide initiators are discussed in Chapter 2. Also in Chapter 2, hazards of organic peroxides and high pressure processes are briefly addressed. Transition metal catalysts are essential to production of nearly three quarters of all polyethylene manufactured and are described in Chapters 3, 5 and 6. Metal alkyl cocatalysts used with transition metal catalysts and their potentially hazardous reactivity with air and water are reviewed in Chapter 4. Chapter 7 gives an overview of processes used in manufacture of polyethylene and contrasts the wide range of operating conditions characteristic of each process. Chapter 8 surveys downstream aspects of polyethylene (additives, rheology, environmental issues, etc.). However, topics in Chapter 8 are complex and extensive subjects unto themselves and detailed discussions are beyond the scope of an introductory text. 

The readers are referred to new references (46-49) and US governmental reports (50-59) for modem site remediation technologies. For completion of a successful site remediation project, all aspects of environmental pollution control (air, noise, water, and soil) must be considered. Oxidation chemically converts hazardous contaminants to non-hazardous or less toxic compounds that are more stable, less mobile, and/or inert. The oxidizing agents most commonly used are ozone, hydrogen peroxide, hypochlorites, chlorine, and chlorine dioxide (46,47). Figme 3 shows a typical chemical oxidation system for site remediation. 

Environmental Contains no heavy metals or other agents harmful to the environment ecologically inert pyrophosphate additive may affect aquatic life or cause algal blooms if released into rivers in Ig. quantities Precaution Avoid contact with strong min. acids or substances liable to decomp, by dust, e.g., peroxides avoid excessive moisture humidity or direct contact with water results in caking Hazardous Decomp. Prods. Lithium salts if prod. dec. by min. acid Storage Store under dry conditions seal container after use Laponite MS [Southern Clay Prods.]... 

Toxicology LD50 (oral, rat) 7400 mg/kg, (skin, rabbit) 10 g/kg TCLo (inh., human) 200 ppm mildly toxic by inhalation, ingestion, and skin contact eye irritant human systemic effects by inh. skin irritant TSCA listed Environmental VOC BODS 0.48 ThOD 2.95 Precaution Flamm. dangerous fire hazard exposed to heat, flame, oxidizers incompat. with NCI3, oxidizing materials may form explosive peroxides, esp. in anhyd. form... 

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