Clean synthesis

Synthesis gas. 150 tonnes of mixed plastics per day produces roughly 350,000 Nm per day of clean synthesis gas (mainly H2/CO) that can be used as feedstock in petrochemical processes. 

J. H. Clark and C.N. Rhodes, Clean Synthesis Using Porous Inorganic Solid Catalysts and Supported Reagents , Royal Society of Chemistry, Cambridge, 2000. 

Electrochemistry is widely used in industry, for example in effluent treatment, corrosion prevention and electroplating as well as in electrochemical synthesis. Electrochemical synthesis is a well-established technology for major processes such as aluminium and chlorine production there is, however, increased interest in the use of electrochemistry for clean synthesis of fine chemicals. The possible green benefits of using electrochemical synthesis include ... 

The first example of biphasic catalysis was actually described for an ionic liquid system. In 1972, one year before Manassen proposed aqueous-organic biphasic catalysis [1], Par shall reported that the hydrogenation and alkoxycarbonylation of alkenes could be catalysed by PtCh when dissolved in tetraalkylammonium chloride/tin dichloride at temperatures of less than 100 °C [2], It was even noted that the product could be separated by decantation or distillation. Since this nascent study, synthetic chemistry in ionic liquids has developed at an incredible rate. In this chapter, we explore the different types of ionic liquids available and assess the factors that give rise to their low melting points. This is followed by an evaluation of synthetic methods used to prepare ionic liquids and the problems associated with these methods. The physical properties of ionic liquids are then described and a summary of the properties of ionic liquids that are attractive to clean synthesis is then given. The techniques that have been developed to improve catalyst solubility in ionic liquids to prevent leaching into the organic phase are also covered. 

Selective monomethylation reactions of methylene-active compounds with dimethylcarbonate. An example of clean synthesis... 

Rueter et al.62 described an efficient and clean synthesis of diethyl-(2-/ -tolyl-ethyl)amine (30) from 2-p-tolylethanol and diethylamine by making use of the benzenesulfonyl chloride resin (26) to catch the intermediate O-alkylated substrate (31) followed by the release (from the intermediate resin) of the final product (30) upon treatment with diethylamine (Fig. 12). 

In 1992, BASF opened a 35 000 tons per year ibuprofen production plant in Bishop, Texas. This plant was the result of the elegant green chemistry route developed by the BHC consortium. The clean synthesis of ibuprofen is an excellent example of how combining catalysis and green chemistry can yield both commercial success and environmental benefits. Ibuprofen is a nonsteroidal, anti-inflammatory painkiller. It is a popular over-the-counter drug against headache, toothache, and muscular pains. You may know it better as Advil , Motrin , or Nurofen. 

Ultrasound has been used for efficient and clean synthesis of polysilanes as well as further conversion of polysilanes to SiC by combining a reducing... 

THE ROLE OF FLUORINE COMPOUNDS IN CLEAN SYNTHESIS 3.1. Fluorous separation technologies... 

The activity of damaged catalysts may be almost completely restored by reduction with clean synthesis gas at a relatively low temperature. It has also been found that the degree of poisoning rises as the partial pressure ratio, PH20/Ph2 increases and the degree of poisoning falls with increasing temperature.74... 

Scheme 1, Polymer-supported reagents in clean synthesis 2.1. The evolution of supported reagents - The perruthenates...

The reduction of mer-trichlorotris(dimethylphenylphosphine)rhenium-(III)1 3 with sodium tetrahydroborate(l —), as described below, provides a clean synthesis of tris(dimethylphenylphosphine)pentahydridorhenium(V),... 

In this book, the main catalytic processes in oil refining and petrochemicals are reviewed with special emphasis on environmental issues they play a historic role in catalysis and illustrate nicely the interplay between chemistry, processes and products. The immense potential (hardly exploited) of zeolites in the clean synthesis of fine chemicals is demonstrated with various examples. 

Acid zeolite catalysts offer a very good alternative for the clean synthesis of these sulfur containing substances. A suitable feed stock is the 4-isopropenyl-l-methyl-1-cyclohexene. In the presence of a commercial beta-zeolite (25) hydrogen sulfide is added to the autoclave at a reaction temperature of 50°C at a pressure of 17 bar. The conversion is 65.1% and the selectivity to 1-p-menthene-8-thiol is 43.9%. These are very promising results and they can be improved by using a commercial H-US-Y zeolite which rendered a conversion of 76.8% and a selectivity of 64.3% (62). 

A number of ILs are hydrophobic, yet they readily dissolve many organic molecules—with the exception of alkanes and alkylated aromatic compounds (e.g., toluene). Among such ILs we find [bmim][PFg], which forms triphasic mixtures with alkanes and water. This multiphasic behavior has decisive implications for clean synthesis. For example, transition-metal catalysts can be exclusively dissolved in the ionic liquid, thus allowing products and by-products to be separated from the ionic liquid by solvent extraction with either water or an organic solvent. This is advantageous when using expensive metal catalysts, as it enables both the ionic liquid and the catalyst to be recycled and reused. Alternatively, some volatile products can be separated from the IL by distillation, as it has negligible vapor pressure. 

Previously Davidson and Triggs have reported that arylboronic acids react with sodium palladate to give the dimeric biaryls. The synthetic utility of this dimerization reaction is, however, limited owing to stoichiometric requirement of the palladium compound. On the other hand, the palladium-catalyzed crosscoupling reaction between arylboronic acids and haloarenes in the presence of bases provides a clean synthesis of biaryls (Eq. 106) In this case, sodium carbonate has been proven to be most effective base. 

This route provides a clean synthesis of silicon-transition-metal bonds because dihydrogen is eliminated as the sole side product. 

Peng Y, Song G (2004) Microwave-assisted clean synthesis of 6-aryl-2,4-diamino-1,3,5-triazines in [bmim][PF6]. Tetrahedron Lett 45 5313-5316... 

Since the thermal decomposition products of QF AsF are all volatile whereas the CioFgAsF is thermally stable and involatile at room temperature, a quantitative conversion of CjoFg to the salt can be achieved. This has settled the composition as C o FgAsF. It is not, however, necessary to employ QFgAsFg as the oxidizer. A convenient, clean synthesis uses a mixture of ASF3 and F2 in SO2CIF. 

Unfortunately, the Mp6" anions that stabilize 02 salts are similar in size to their noble metal relatives and, with alkali cations, give solid solutions, in this case a 1 1 mix of PtF " and AsF6. a clean synthesis is possible, however, if an aHF solution of O2F is used in place of the O2+ salt. 

And this provided a clean synthesis for the NOMFg salts (see Ref. 23) which could not be obtained cleanly from the interaction of nitric oxide with the hexafluorides, since the NOMFe salts (M = Ir, Pt) were able to oxidize NO to produce (NO)2 MFe. But F2 was not the only gaseous product of the ONF/MFe reactions, the new nitrogen oxide trifluoride also being a product, which was present in good yield in the IrFe reaction (see Ref. 25), ideally ... 

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