Precursors future applications

The book is arranged in 14 chapters. After discussing general aspects, separation of hydrocarbons from natural sources and synthesis from Ci precursors with the most recent developments for possible future applications, each chapter deals with a specific type of transformation of hydrocarbons. Involved fundamental chemistry, including reactivity and selectivity, as well as stereochemical considerations and mechanistic aspects are discussed, as are practical applications. In view of the immense literature, the coverage cannot be comprehensive and is therefore selective, reflecting the authors own experience in the field. It was attempted nevertheless to cover all major aspects with references generally until the early 1994. 

Numerous ceramics are deposited via chemical vapor deposition. Oxide, carbide, nitride, and boride films can all be produced from gas phase precursors. This section gives details on the production-scale reactions for materials that are widely produced. In addition, a survey of the latest research including novel precursors and chemical reactions is provided. The discussion begins with the mature technologies of silicon dioxide, aluminum oxide, and silicon nitride CVD. Then the focus turns to the deposition of thin films having characteristics that are attractive for future applications in microelectronics, micromachinery, and hard coatings for tools and parts. These materials include aluminum nitride, boron nitride, titanium nitride, titanium dioxide, silicon carbide, and mixed-metal oxides such as those of the perovskite structure and those used as high To superconductors. 

ZnO is being regarded as one of the important metal oxide semiconductors for future applications. Since its chemical and physical properties are highly dependent on composition and shape (defects), reliable methods are necessary to ensure control over the latter. The heterocubane (MeZnO Pr)4 was shown to be a suitable organometallic precursor for gas-phase CVS and solid-state synthesis of nanoscaled Interestingly, highly... 

In this paper, we present the metastable a-polymorph of strontium carbodiimide as a novel pseudochalkogenide host lattice for divalent europium ions. Because of the high thermal inertness and cationic nitrogen coordination of this compound looks like a promising candidate for future applications. Furthermore, Sr-based compounds are ideal host lattices for divalent rare-earth-ions, simply because Sr " " is spectroscopically inactive, and Sr and Eu have comparable ionic rachi and identical charge. As a synthetic challenge, however, the preparation of phase-pure samples is required. Inspired by the reaction of EuN, BN, and NaN3 to form Eu3(NBN)2, and the synthesis of In2.24(NCN)3 from InBr and NaCN, we developed a new flux route based on the metal halide, alkaline cyanide, and alkaline azide, which act as precursors for the synthesis of structurally rather complex rare-earth and alkaline-earth cyanamides and... 

The results in this section clearly demonstrate that virtually any epoxide can be accessed in enantio- and diastereo-merically pure form from alkene precursors. The Sharpless and Shi epoxidation methods have dominated the recent applications to cascade reactions in synthesis. However, new protocols offer experimental facility and substrate scope that will lead to future applications in complex molecule construction. 

Application to both Type I and Type II intramolecular Diels-Alder cycloaddition has also met with appreciable success, the most efficient catalyst for these reactions being imidazolidinone 21 (Scheme 7) [51, 52]. The power of the inttamolecular Diels-Alder reaction to produce complex carbocyclic ring structures from achiral precursors has frequently been exploited in synthesis to prepare a number of natural products via biomimetic routes. It is likely that the ability to accelerate these reactions using iminium ion catalysis will see significant application in the future. 

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