Solvent systems, green

The discussion is organized in the following order First the advantages of HRC scheme, relative to the industrial (i.e., heterogenous) process are briefly commented on second, the relevance of celMose activation and the physical state of its solution to optimization of esterification are discussed. Finally, the use of recently introduced solvent systems and synthetic schemes, designed in order to obtain new, potentially useful cellulose esters with controlled, reproducible properties is reviewed. A comment on the conformity of these methods with the concepts of green chemistry is also included. 

Figure 7.7 Separation of ethynyl estrogens on silica gel 60 HPTLC plates using two 15-min developments in the solvent system hexane-chloroform-carbon tetrachloride-ethanol (7 18 22 1 v/v). Identification O methyl green (lane marker) 1 17a-ethynylestradiol ...

Photoreduction of cobalt(III) complexes in nonaqueous solvent systems has been little studied because of the limited solubility of cobalt(III) complexes and their tendency to photooxidize the solvent. Irradiation with 365-mjj. light of cis- or trans-Co(en)2C 2 + and Co(en)2Cl(DMSO)2+ in dimethylsulfoxide (DMSO) leads rapidly to production of a green tetrahedral cobalt(II) product apparently with concurrent solvent oxidation.53,71 Irradiation with 365-mjx light of the molecular Co(acac)3 in benzene rapidly gives a red precipitate which may be the cobalt(II) acetylacetonate.53... 

M. Onaka, Efficient lipase-catalyzed enantioselective acylation in an ionic liquid solvent system. In Ionic Liquids as Green Solvents, R. D. Rogers, K. R. Seddon, Eds., ACS Symposium Series Vol. 856, ACS Washington D.C., 2003, p 251. 

To test the practical applicability of the quinoline solvent systems, samples of raw, crushed (< 125 p) Green River oil shale were extracted in the previously described manner (Table I). The samples lost 37% of their weight, suggesting that a large portion of the quartz and other silicates had been dissolved from the rock. 

Method. The amino acid derivatives are prepared by adding disyl chloride (1 mg/ml in acetone) to an equal volume of a solution of the amino acid (ca. 5 10 4 jumoles/ml in 0.1 M sodium bicarbonate solution). The reaction is allowed to proceed for 3 h at room temperature. The solvent is evaporated and the residue is dissolved in 1 ml of acetone-methanol (1 1) for application to a thin-layer plate of silica gel. A number of solvent systems used for the separation of amino acid derivatives is given in Table 4.14. After chromatography, the plates are dried at 10S °C for S min, cooled to room temperature and dipped in a solution of sodium ethoxide (S g of sodium per 100 ml of 96% ethanol). The plate is observed immediately under UV light at 365 nm. The amino acid derivatives appear yellow-green. 

Handbook of Green Chemistry and Technology, J. H. Clark and D. J. Macquarrie, Eds., Blackwell Publishing 2002, 540 pp., ISBN 0-632-05715-7. This collection of 22 review essays covers all the important areas of green chemistry, including environmental impact and life-cycle analysis, waste minimization, catalysts and their industrial applications, new synthesis methods, dean energy, and novel solvent systems. The chapters are well referenced and contain pertinent examples and case studies. 

Wang J-Q, Cai F, Wang E et al (2007) Supercritical carbon dioxide and poly(ethylene glycol) an environmentally benign biphasic solvent system for aerobic oxidation of styrene. Green Chem 9(8) 882-887... 

Table 5-16. Nucleophilic parameters N+ for various (nucleophile + solvent) systems, based on reactions of malachite green or the tris-4-anisylmethyl cation [597],...

One of the areas gamering attention in catalysis research has been the development of green or enviromnentally benign catalytic systems. For olefin metathesis, the trend has been to develop catalytic systems that can be efficiently recycled. Success in this area has multiple implications for OM processes. First, a recyclable catalyst will give overall more turnovers per catalyst molecule, and thereby be more economical. Second, a catalyst that can be efficiently recycled (low loss of activity over repeated uses) leaches less Ruthenium into the product and thus less expensive processing costs. To this end inunobihzation of the olefin metathesis catalysts on a variety of sohd supports and utilization of nonorganic solvent systems have been explored. 

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