Alternating toxicity

Because osmium tetroxide is expensive, and its vapors are toxic, alternate methods have been explored for effecting vic-glycol formation. In the aliphatic series, olefins can be hydroxylated with hydrogen peroxide with the use of only a catalytic amount of osmium tetroxide. Anhydrous conditions are not necessary 30% hydrogen peroxide in acetone or acetone-ether is satisfactory. The intermediate osmate ester is presumably cleaved by peroxide to the glycol with regeneration of osmium tetroxide. When this reaction was tried on a A -steroid, the product isolated was the 20-ketone ... 

Since osmium tetroxide is expensive and toxic, alternate reagents were also explored. This has led to the use of potassium permanganate by two different groups. ... 

Probably the most fundamental problem facing the development of greener products and processes is the measurement of progress and the development of appropriate methods for comparison of alternatives. In many instances it will be obvious that improvements have been made, for example when a toxic material is replaced by a non-toxic alternative, keeping all other process conditions essentially the same, or when the energy requirement of a process is reduced. 

Two options are being developed at the moment. The first is to produce 1,2-propanediol (propylene glycol) from glycerol. 1,2-Propanediol has a number of industrial uses, including as a less toxic alternative to ethylene glycol in anti-freeze. Conventionally, 1,2-propanediol is made from a petrochemical feedstock, propylene oxide. The new process uses a combination of a copper-chromite catalyst and reactive distillation. The catalyst operates at a lower temperature and pressure than alternative systems 220°C compared to 260°C and 10 bar compared to 150 bar. The process also produces fewer by-products, and should be cheaper than petrochemical routes at current prices for natural glycerol. The first commercial plant is under construction and the process is being actively licensed to other companies. 

Quinoxalines 85 have been prepared by the reaction of diols with benzene-1,2-diamines in the presence of a ruthenium catalyst <06TL5633>. Iodobenzene diacetate has been suggested as a less toxic alternative to lead tetraacetate for the oxidative cyclisation of iminooximes to quinoxaline iV-oxides 86 <06TL4969>. 

An MCS treatment center that will provide physician referrals in U.S., Canada and other countries. A health educator on staff will answer questions by telephone or via the center s Web site. They have published a book, Less Toxic Alternatives, as a resource guide for all sorts of MCS-aware organizations and products avail-... 

Free halogens are generally inconvenient to use, owing to their toxic and corrosive nature, but can be replaced by quaternary ammonium polyhalides. Quaternary ammonium tribromides are well established [e.g. 1] as solid, readily handled and relatively non-toxic alternatives for electrophilic bromine. More recently, other quaternary ammonium polyhalides have been produced, which together with the tribromides, have wide application as catalysts or in stoichiometric quantities in electrophilic substitution and addition reactions, oxidations, etc. 

Regulatory facts EPA, FDA, Consumer Product Safety Commission General facts many household products are necessary, but often less toxic alternatives are available... 

Environmental serious environmental concern (i.e. mercury, detergents) Recommendations use less toxic alternatives, dispose of hazardous wastes properly... 

Avoiding the use of toxic products can take the form of avoiding chemical products altogether for certain jobs, choosing products made from safer ingredients, and buying ready-to-use dilutions rather than concentrates. Table 18.4 shows some examples of less-toxic alternatives for common products. 

Although severe disruption in the sleep-wake cycle is a common feature of dementia, the use of BZDs in such cases may also produce significant behavioral toxicity. Alternative drug approaches include bedtime use of olanzapine in nondepressed patients or trazodone in depressed patients. 

The aminoglycoside antibiotics are discussed in Chapter 45. Kanamycin has been used for treatment of tuberculosis caused by streptomycin-resistant strains, but the availability of less toxic alternatives (eg, capreomycin and amikacin) has rendered it obsolete. 

The treatment of choice for extraintestinal infections is metronidazole plus a luminal amebicide. A 10-day course of metronidazole cures over 95% of uncomplicated liver abscesses. For unusual cases in which initial therapy with metronidazole has failed, aspiration of the abscess and the addition of chloroquine to a repeat course of metronidazole should be considered. Dehydroemetine and emetine are toxic alternative drugs. 

It is suggested that whereas metal ions usually penetrate poorly into a microbial cell the formation of a metal chelate may facilitate metal ion uptake from the medium in which the cell is growing, leading to toxicity. Alternatively, diffusion of the chelating agent into the cell may lead to a critical depletion of essential metal ions in the cell. Metal [Fe(II), Cu(II), Cd, Ni, Ru(II)] chelates of 1,10-phenanthroline bases are lethal to cultured mammalian cells at concentrations down to 0.1 /uM98). This cytotoxicity limits their possible medical uses to topical applications. 

A review of the use of process and treatment plant chemicals is required to identify those that have the potential to contribute to toxicity. For each chemical the following should be determined i) availability of current MSDS and toxicity test data for species of interest, ii) purpose and volume used (volumes used are typically available from the supplier), iii) whether the amount can be reduced or reused, iv) whether less toxic alternatives are available, and v) if it is possible to avoid discharge of the chemical (U.S. EPA, 1989 1999). Even a slight overdosing of effluent treatment chemicals (e.g., polymers, chlorine) could result in potentially toxic concentrations in the final effluent, since these chemicals do not have the... 

The FSTR ( Freshwater Salinity Toxicity Relationship ) model (Mount et al., 1997) was also applied with selected Daphnia magna samples. The results indicated that for most samples, the model accurately predicted toxicity. Percent differences between measured and predicted TUs were generally less than or equal to 20%. In several cases the model either over- or under-estimated toxicity. Its failure to consistently predict mortality was supported by Mount et al. (1997), who observed that in its preliminary application in field-collected samples, the Daphnia magna model tended to over-predict toxicity. Alternatively, the presence of Cu could also explain why measured toxicity was occasionally higher than the predicted toxicity. 

Recent research has focused on the development of enzymatic processes for the treatment of wastewaters, solid wastes, hazardous wastes, and soils. The environmental applications may be classified according to their objectives. For example, some processes are specifically designed to accomplish the transformation of target pollutants in wastewater streams to reduce toxicity. Alternatively, the conversion of waste materials can sometimes be achieved in a manner that produces a product with commercial value. Some applications that have recently been identified will be outlined below. 

More recently, a new class of non-metallic oxidation reagents has been reported - the hy-pervalent iodine complexes [19]. Phenyliodine(III) diacetate (PIDA) and phenyliodine(III) bis(trifluoroacetate) (PIFA) have proven to be very efficient reagents that give rise to higher regioselectivity than other oxidants in some reactions and, more importantly, offer a mild and non-toxic alternative to the heavy metals. 

Baking soda is a non-toxic alternative, but it is much less effective. Therefore, it requires even more scrubbing. An abrasive paste can be made by mixing baking soda and water. The basic properties of baking soda also have a small effect on grease and grime if it is applied to the oven and left for several hours. 

Use safer solvents and reaction conditions Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals. More and more research demonstrates reactions may not require solvents to proceed in clean and quantitative yields. When solvents are required, water, C02, ethanol, or other low-toxicity alternatives are preferred to traditional organic solvents. 

The mitigation of corrosion can be achieved economically by the use of corrosion inhibitors. Chromate has been extensively used in an aqueous environment for the protection of aluminium, zinc and steel. Although chromates are cheap and effective, they are not acceptable because of their toxicity. Alternate inhibitors such as molybdates, organic inhibitors such as phosphonates, mixtures of phosphates, borates and silicates and surfactants like sulfonates have been used in place of chromates. Chromates are anodic inhibitors and help to form passive oxide on the metal surface. 

HNS is a temperature stable secondary explosive, which is particularly useful for blasting in very hot oil deposits, because it is stable to approx. 320 °C. Problems in this area however relate to the initiator, since HNS is relatively difficult to initiate. The most useful initiator is cadmium azide, Cd(N3)2, (7dec. ca. 295 °C). However, since cadmium is toxic, alternatives are currently being sought after. The two most promising compounds to date to replace Cd(N3)2 are silver nitriminotetrazolate ( Idee. = 366 °C) and di(silveraminotetrazole) perchlorate (rdec =319°C) (Fig. 2.3) [10]. ... 

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