Cleaner chemical process

To overcome health and environmental problems at the source, the chemical industry must develop cleaner chemical processes by the design of innovative and environmentally benign chemical reactions. Green chemistry offers the tools for this approach. ... 

Reaction media such as ionic liquids, fluorous solvents and supercritical fluids may offer a solution in avoiding some of the above mentioned problems. In addition to the physicochemical properties of solvents that are crucial when selecting a solvent for a particular task, within the context of producing cleaner chemical processes, other criteria are also important. 

Applied Electrotechnology for Cost Effective and Cleaner Chemical Processes the Practical Solution. ICI Chemicals Polymers Ltd CC/22561/IEd/53/890. 

Develop new cleaner chemical processes to replace environmentally unacceptable methods. 

In the future, development and synthesis of naturally based polyurethane will be largely driven by three factors the need to derive more carbon for chemical process from renewable substances Instead of oil reserves, to develop cleaner chemical processes, and to avoid disturbing the ecosystems, an important benefit of renewable feedstocks compared with petroleum. 

Another example of an environmentally benign solvent for Heck chemistry is supercritical carbon dioxide (Scheme 44),[ 2],[i93] Undoubtedly, the future need for cleaner chemical processing is great. 

Hydrogenation with achiral catalysts has been widely used and is likely to experience increased development in the coming years. The concept of directed hydrogenation led to an increase in the ability to control diastereoselectivity, which is often as important to control in synthetic sequences as enantioselectivity. Furthermore, the drive for cleaner chemical processes is likely to make the hydrogenation of functional groups such as esters, adds, nitriles, and nitro groups important for the production of achiral products without the use of main group metal hydrides. 

In other words, we try to mimic enzymes by attaching centers for homogeneous catalysis to polymer chains we want to learn from nature how to conduct chemical processes in a cleaner, more selective and milder way. In this respect it is of great importance that we can adapt, just like in enzymes, the micro-environment of the catalytic centers by modification of neighbouring polymer chain segments. 

The first approach may involve cleaner synthesis processes, improved technology, recycling of residues, improved use of catalysts, and generally, every technique integrated into the process that leads to less waste whereas the second one is an end-of-pipe treatment of the waste that is inevitably produced by a chemical process. Both approaches have to be combined so that our releases into the environment are as minimal and harmless as possible. 

Despite more than 20 years of study, the application of microwave irradiation to chemical process development is still in relative infancy. Microwave equipment companies continue to address the requirements for large-scale continuous flow and other reactors.80 The availability of versatile equipment, and preferably a champion in a chemical process development department, would encourage evaluation of the technology to identify those reactions where the main advantage, enormous reduction in reaction times (often with cleaner reactions and yield increases beyond those achievable using conventional conditions), can be harnessed in practical terms. 

Conclusion. From a chemical process development perspective, the principal advantage favoring the use of microwave irradiation in promoting chemical reactions lies in achieving shorter reaction times. If cleaner reactions giving higher yields are also demonstrated, they add greatly to the attractiveness. 

Supercritical fluids, particularly supercritical C02, scC02, are attractive solvents for cleaner chemical synthesis. However, optimisation of chemical reactions in supercritical fluids is more complicated than in conventional solvents because the high compressibility of the fluids means that solvent density is an additional degree of freedom in the optimisation process. Our overall aim is to combine spectroscopy with chemistry so that processes as varied as analytical separations and chemical reactions can be monitored and optimised in real time. The approach is illustrated by a brief discussion of three examples (i) polymerisation in scC02 (ii) hydrogen and hydrogenation and (iii) miniature flow reactors for synthetic chemistry. 

Catalysis refers to the phenomenon by which the rate of a chemical reaction is accelerated by a snbstance (the catalyst) not appreciably consnmed in the process. The term catalysis was coined by Berzelins in 1835 and scientifically defined by Ostwald in 1895, but applications based on catalysis can be traced back to thousands of years ago with the discovery of fermentation to produce wine and beer. Nowadays, catalysts are used in 80% of all chemical industrial processes, and create annual global sales of about 1500 billion dollars and contribute directly or indirectly to approximately 35% of the world s GDP. Catalysis is central to a myriad of applications, including the manufacture of commodity, fine, specialty, petro-, and agro- chemicals as well as the production of pharmaceuticals, cosmetics, foods, and polymers. Catalysis is also an important component in new processes for the generation of clean energy, and in the protection of the enviromnent both by abating environmental pollutants and by providing alternative cleaner chemical synthetic procedures. 

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