Recycling alternatives

Some recycling alternatives use whole tires, thus requiring no extensive processing other alternatives require that tires be split or punched to make products and still other alternatives involve tires that are finely ground enabling the manufacture of crumb rubber products. Some applications for each alternative are listed below  

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Separators working at unsteady conditions produce intermediates with compositions which do not allow them to be recycled. Alternatively, if the intermediate can be recycled, a nonoptimal recycle might produce (additional) unwanted byproducts in the reactor. 

A safe recyclable alternative to lithium perchlorate-diethyl ether mixture [54]... 

Catalytic oxidation of waste HBr offers a more environmentally friendly recycle alternative than oxidation with chlorine, since catalytic oxidation yields byproduct water (eqn. 5) rather than salt requiring disposal or deep welling. 

Another review concerning the synthesis of cyclic peroxides has been published and a solid-supported catalyst 231 for both cycloaddition reactions and singlet oxygen ene reactions was synthesized and demonstrated to be an efficient, mild, and recyclable alternative to solution-phase photooxygenation catalysts <2006JOC724>. 

Room-temperature ionic liquids may be used as green recyclable alternatives to chlorinated solvents for stereoselective halogenation.577 The bromination of alkenes and alkynes in [bmim][Br] is a/m -stereospecific, whereas that of 1,3-dienes gives selectively the 1,4-addition products. The reactions of arylacetylenes, however, are not selective when carried out in [bmim][PF6]. Tetraethylammonium trichloride, a stable crystalline solid may be used in the chlorination of alkenes and alkynes to afford the products with exclusive anti stereoselectivity.578 It has... 

REACTION-SEPARATION PROCESSES OPTIMAL RECYCLE ALTERNATIVES AND MINIMUM REQUIRED SELECTIVITY 5.28... 

As described in earlier chapters, the volatility of solvents is of crucial important in their applications. In 2007, the groups of Liotta, Eckert and Jessop first reported on the formation and use of piperylene sulfone (PS) as a recyclable alternative to dimethyl sulfoxide (DMSO) (Figure 9.11). DMSO, in addition to dimethylformamide (DMF) and hexamethylphosphoramide (HMPA), is a widely used dipolar, aprotic solvent. However, it is difficult to remove from products by distillation and is rarely recycled. In contrast, PS decomposes cleanly at temperatures above 100°C to give ra -l,3-pentadiene and sulfur dioxide, which reform PS at room temperature (Figure 9.11). 

Figure 9.11 How piperylone sulfone can be used as a labile, recyclable alternative to DMSO (a) the thermally reversible reaction to form the solvent (b) the recycling process. [Reprinted with permission from Chem. Commun. 2007, 1427-1429. Copyright 2007 The Royal Society of Chemistry.]...

Asymmetric hydrogenation. As ionic liquids at room temperature the imidazolium salts are a recyclable alternative to dipolar aprotic solvents. The tetrafluoroborate salt serves as a medium in the asymmetric hydrogenation of... 

Ionic liquids (ILs) are a group of organic salts that are liquid at room temperature. They have unique chemical and physical properties, including being air and moisture stable, a high solubility power, and virtually no vapor pressure. " Because of these properties, they can serve as a green recyclable alternative to the volatile organic compounds that are traditionally... 

The moisture- and air-stable ionic liquids, l-butyl-3-methylimidazolium tetra-lluoroborate [bmim]BF and l-butyl-3-methylimidazolium hexafluorophosphate [bmim]PFg, were used as green recyclable alternatives to volatile organic solvents for the ethylenediaimnonium diacetate-catalyzed Knoevenagel condensation between aldehydes or ketones with active methylene compounds. As described by Su et al. [57], the ionic hquids containing a catalyst were recycled several times without decrease in yields and reaction rates. In the case of 2-hydroxybenzaldehyde, the reactions led to the formation of 3-substituted coumarin derivatives in high yields of up to 95% (Scheme 17.11). When ethyl cyanoacetate was used, 2-imino-27f-l-benzopyran-3-carboxyhc acid ethyl ester was formed. 

DOE O 450.1, sec. 5.d.(3) EO 13101, sec. 601(l)(b) 4.5.2 Contractors shall set goals to increase the procurement of products that are made with recovered materials to maximize the number of recycled products purchased, relative to non-recycled alternatives. 

Waste management and recycling alternatives are presented and discussed in Chapter 3. The poor reputation of used plastics is gradually dissipating, as methods to recover and recycle post-consumer waste plastics improve and reliable high-quality supplies of reusable material can be guaranteed. 

Figure 5 lists general recycling alternatives for used rubber [23]. 

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