Industrial-scale organic synthesis

The transition metal-catalyzed addition of the Si-H bond of a hydrosilane across a C=C or C=C bond is a transformation of considerable importance in both large-scale industrial processes and in small-scale organic synthesis.Perhaps the most common industrial application of catalytic hydrosilylation is the platinum-catalyzed cross-linking of vinylsilane polymers with hydrosilanes. The interest in catalytic hydrosilylation in organic synthesis... 

Although a few simple hydrides were known before the twentieth century, the field of hydride chemistry did not become active until around the time of World War II. Commerce in hydrides began in 1937 when Metal Hydrides Inc. used calcium hydride [7789-78-8J, CaH2, to produce transition-metal powders. After World War II, lithium aluminum hydride [16853-85-3] LiAlH, and sodium borohydride [16940-66-2] NaBH, gained rapid acceptance in organic synthesis. Commercial appHcations of hydrides have continued to grow, such that hydrides have become important industrial chemicals manufactured and used on a large scale. 

The main disadvantages of Evans auxiliaries 22 and 23 are that they are expensive to purchase and inconvenient to prepare, as the preparation involves the reduction of (5 )-valine 24 to water-soluble (b )-valinol, which cannot be readily extracted to the organic phase. The isolation of this water-soluble vali-nol is difficult and requires a high vacuum distillation, which is not always practical, especially on an industrial scale. Therefore, an efficient synthesis of Evans chiral auxiliary 25 has been developed, as depicted in Scheme 2-1930 ... 

Chlorinated aromatics, including monochlorobenzene (MCB), o-dichloroben-zene (o-DCB), and p-dichlorobenzene (p-DCB), are the major chlorinated aromatic species produced on an industrial scale. MCB is used as both a chemical intermediate and a solvent. As an intermediate, it is used to produce chloroni-trobenzene, pesticides, and pharmaceutical products. In solvent applications, MCB is used in the manufacture of isocyanates. Its high solvency allows it to be used with many types of resins, adhesives, and coatings. The o-dichlorobenzene is used primarily for organic synthesis, especially in the production of 3,4-dichlo-roaniline herbicides. Like MCB, it can be used as a solvent, especially in the production of isocyanates. It is also used in motor oil and paint formulations. The p-dichlorobenzene is used as a moth repellent and for the control of mildew and fungi. It also is used for odor control. It is a chemical intermediate for the manufacture of pharmaceuticals and other organic chemicals. 

For each step of a synthesis, a large toolbox of chemistries is available. Most of them have been developed on laboratory scale by academia over the last century and subsequently adapted to industrial scale. For example, evaporating to dryness had to be elaborated to concentrate in a thin-film evaporator and precipitate by addition of isopropanol. The two most comprehensive handbooks describing organic synthetic methods are the Encyclopedia of... 

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