Recent Developments and Future Prospects

This asymmetric epoxidation technology affords high yields and enantiose-lectivities with a broad range of allylic alcohol substrates, and has been widely applied in organic synthesis [34-38], The original procedure [33] required stoichiometric amounts of the titanium tartrate (titanium is a rather unreactive epoxidation catalyst) but was subsequently improved to the extent that 5-10 wt.% is sufficient. 

Although these reactions obviously involve intramolecular oxygen transfer within a titanium(IV) tartrate-ally lie alcohol-alkyl hydroperoxide complex, analogous to the vanadium-catalyzed epoxidations discussed above, the exact nature of the catalytic species and the mechanism of enantioselection remain controversial [39, 40], 

In this context it is worth noting that neither the titanium(IV) tartrate catalyst nor other metal catalyst-alkyl hydroperoxide reagents are effective for the asymmetric epoxidation of unfunctionalized olefins. The only system that affords high enantioselectivities with unfunctionalized olefins is the manganese(III) chiral Schiff s base complex/NaOCl combination developed by Jacobsen [42]. There is still a definite need, therefore, for the development of an efficient chiral catalyst for asymmetric epoxidation of unfunctionalized olefins with alkyl hydroperoxides or hydrogen peroxide. 

The Oxirane process is a mature technology that has stood the test of time. Both ARCO and Shell have been successfully operating for more than two decades. More recently a heterogeneous titanium-substituted silicalite (TS-1) catalyst was developed by Enichem [43, 44]. In contrast to the Shell Ti /Si02 catalyst, TS-1 has a hydrophobic surface and is a remarkably effective catalyst for a variety of liquid-phase oxidations with 30 % aqueous hydrogen peroxide, including epoxidation [44]. It has been commercialized for the hydroxylation of phenol to 

An added advantage of the TS-1 catalyst, which could have commercial benefits, is the possibility for accomplishing shape-selective epoxidations. Owing to the limited dimensions (5.6 A X 5.4 A) of its micropores, linear olefins are epox-idized much faster than branched or cyclic olefins, e.g., 1-hexene is smoothly epoxidized while cyclohexene is virtually unreactive [45]. This reactivity is completely the opposite to that observed with the metal catalyst-alkyl hydroperoxide reagents (see earlier). It could be utilized in, for example, the selective epoxidation of linear olefins in mixtures of linear and branched or cyclic olefins. 

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H. Nikaido iu M. Stalton and G. A. Shockman, eds., p-Eactam Mntibiotics Mode of Fiction, Recent Developments and Future Prospects, Academic Press,... 

Hakim NS. 2003. Recent developments and future prospects in pancreatic transplantation. Exp Clin Transplant. 1 26-34. 

Buzzanell P, US Department of Agriculture. Corn Sweeteners Recent Developments and Future Prospects. Paper presented at Azucar 95 Foro Internacional, Guadalajara, Mexico October 10, 1995. 

Spyropoulos, G. (ed) (2000). Health, Safety and Working Conditions in Greece, Recent Developments and Future Prospects, Athens/Komotim Sakkoulas Publishers, (in Ch eek). 

Tip-enhanced Raman Spectroscopy -Recent Developments and Future Prospects... 

This chapter first gives an overview of cellulose raw materials and their molecular and supermolecular structures. The principles of shaping cellulose into fibres, films, and nonwovens by means of solution techniques are then outlined followed by a section on properties and market applications of these materials. Derivatives of cellulose are presented with special emphasis on thermoplastic cellulose esters, typical plasticizers, and promising reinforcing materials. Finally, recent developments and future prospects of cellulose materials are reviewed as far as the above applications are concerned. This book does not cover the important applications of cellulose and ligno cellulose fibres for reinforcing thermoplastics, like wood plastic composites (WPC) and natural fibre reinforced plastics (NFRP), since in these cases cellulose does not substitute a thermoplastic. 

R641 T. Koizumi, Recent Development and Future Prospects in Cryocooler Technologies , Oyo Butsuri, 2011, 80, 407. 

Ilium L (2012) Nasal drug delivery-recent developments and future prospects. J Control Release 161 254—263... 

K. L. Beattie, N. J. Logsdon, R. S. Anderson, J. M. Espinosa-Lara, R. Maldonado-Rodriguez, J. D. I. Frost, Gene synthesis technology recent development and future prospects. Biotechnol. Appl. Biochem. 1988,10, 510 521. 

Omtvedt, J.P., Alstad, J., Eberhardt, K., Eure, K., Malmbeck, R., Mendel, M., Nahler, A., Skamemark, G., Trautmann, N., Wiehl, N., Wierczinski, B. Review of the SISAK system in transactinide research recent developments and future prospects. J. Alloys Compd. 271-273, 303 (1998)... 

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