Industrial organic synthesis

Acid—Base Catalysis. Inexpensive mineral acids, eg, H2SO4, and bases, eg, KOH, in aqueous solution are widely appHed as catalysts in industrial organic synthesis. Catalytic reactions include esterifications, hydrations, dehydrations, and condensations. Much of the technology is old and well estabhshed, and the chemistry is well understood. Reactions that are cataly2ed by acids are also typically cataly2ed by bases. In some instances, the kinetics of the reaction has a form such as the following (9) ... 

In a catalytic asymmetric reaction, a small amount of an enantio-merically pure catalyst, either an enzyme or a synthetic, soluble transition metal complex, is used to produce large quantities of an optically active compound from a precursor that may be chiral or achiral. In recent years, synthetic chemists have developed numerous catalytic asymmetric reaction processes that transform prochiral substrates into chiral products with impressive margins of enantio-selectivity, feats that were once the exclusive domain of enzymes.56 These developments have had an enormous impact on academic and industrial organic synthesis. In the pharmaceutical industry, where there is a great emphasis on the production of enantiomeri-cally pure compounds, effective catalytic asymmetric reactions are particularly valuable because one molecule of an enantiomerically pure catalyst can, in principle, direct the stereoselective formation of millions of chiral product molecules. Such reactions are thus highly productive and economical, and, when applicable, they make the wasteful practice of racemate resolution obsolete. 

The emergence of the powerful Sharpless asymmetric epoxida-tion (SAE) reaction in the 1980s has stimulated major advances in both academic and industrial organic synthesis.14 Through the action of an enantiomerically pure titanium/tartrate complex, a myriad of achiral and chiral allylic alcohols can be epoxidized with exceptional stereoselectivities (see Chapter 19 for a more detailed discussion). Interest in the SAE as a tool for industrial organic synthesis grew substantially after Sharpless et al. discovered that the asymmetric epoxidation process can be conducted with catalytic amounts of the enantiomerically pure titanium/tartrate complex simply by adding molecular sieves to the epoxidation reaction mix-... 

The next milestone in the development of organic synthesis was the preparation of the first synthetic dye, mauveine (aniline purple) by Perkin in 1856 Perkin, 1856, 1862). This is generally regarded as the first industrial organic synthesis. It is also a remarkable example of serendipity. Perkin s goal was the synthesis of the antimalarial drug quinine by oxidation of N-allyl toluidine (Fig. 2.4). 

Uses Solvent for cellulose ethers and paints azeotropic distillation agent motor fuel extractions of fats and wax shoe industry organic synthesis. 

Uses Solvent standardized hydrocarbon manufacturing paraffin products jet fuel research paper processing industry rubber industry organic synthesis. 

Alkaline earth metal oxides have been used as solid base catalysts for a variety of organic transformations. Excellent reviews by Tanabe 4) and Hattori 2,3,7) provide detailed information about the catalytic behavior of alkaline earth metal oxides for several organic reactions of importance for industrial organic synthesis. In this section, we describe in detail reactions that have been reported recently to be catalyzed by alkaline earth metal oxides. 

The desperate need for more catalytic methodologies in industrial organic synthesis is nowhere more apparent than in oxidation chemistry. For example, as any... 

Insect pheromones provide ideal targets for industrial organic synthesis for a number of reasons. First, pheromones cannot be isolated in quantity from natural sources, so they must be synthesized if they are to be used. In addition, they are active in minute quantities, so the synthesis of large amounts is not necessary. Finally, most have relatively simple structures and can be synthesized in a relatively small number of steps. Of course, the stereochemistry of these steps must be carefully controlled. 

Although catalytic hydrogenation is a mature technology that is widely applied in industrial organic synthesis, new applications continue to appear, sometimes in unexpected places. For example, a time-honored reaction in organic... 

The time is ripe for the widespread application of biocatalysis in industrial organic synthesis and according to a recent estimate [113] more than 130 processes have been commercialised. Advances in recombinant DNA techniques have made it, in principle, possible to produce virtually any enzyme for a commercially acceptable price. Advances in protein engineering have made it possible, using techniques such as site directed mutagenesis and in vitro evolution, to manipulate enzymes such that they exhibit the desired substrate specificity, activity, stability, pH profile, etc. [114]. Furthermore, the development of effective immobilisation techniques has paved the way for optimising the performance and recovery and recycling of enzymes. 

The main underlying theme is the application of catalytic methodologies -homogeneous, heterogeneous and enzymatic - to industrial organic synthesis. The material is divided based on the type of transformation rather than the type of catalyst This provides for a comparison of the different methodologies, e.g. chemo- vs biocatalytic for achieving a particular conversion. 

Weinberg, N. L., Introduction to Industrial Organic Synthesis. in Electrosynthesis From Laboratory to Pilot to Production Genders, J. D. Pletcher, D., Eds. The Electrosynthesis Company Inc. Elmhurst, New York 1990, pp. 1-13. 

Singlet oxygen is involved in many important chemical processes and photochemical applications, including photodynamic therapy (Special Topic 6.23), photocarcinogeneity (Special Topic 6.7) and phototoxicity (Special Topic 6.22), chemiluminescence (Section 5.6), atmospheric photochemistry (Special Topic 6.21), polymer degradation (Special Topic 6.13), photosynthesis1389 (Special Topic 6.25) or industrial organic synthesis (Special Topic 6.20). 

Some industrial organic synthesis reactions take place in the presence of aqueous caustic soda. A typical exanqile is the dehydrogenation of amino alcohols to amino carboxylic acid salts, which is typically conducted at 1.0 MPa and 393K-483K in a concentration of caustic up to 50wt%. Under such harsh conditions, most supported copper catalysts cannot be used due to dissolution of... 

Table 5.26. Harmful organic substances contained in emissions from the production of important compounds in industrial organic synthesis... 

As stated in Section 5.2.2.5.1, biocatalysis is stiU a very small niche area within the field of industrial organic synthesis in general. Even though the combination of ILs and biocatalysts may offer several exciting opportunities, we do not believe that this will change the overall position of biocatalysis significantly. Rather, the combination of ILs and biocatalysis will only become yet another niche area within the field of biocatalysis. 

Semibatch reactors (SBRs) are very common in industrial organic synthesis in general. The basic principle is that a reactant is placed in the reactor and the same or a second reactant, usually the latter, is added continuously. The product... 

As may be expected, K a j ar is always greater than Vpfr- The effect, which is most marked at high conversions, decreases with increasing order. At conversions close to 100%, laminar/ PFR around 1.5 for a first-order reaction, decreasing to about 1.3 for a second-order reaction. As laminar flow reactors are not common in industrial organic synthesis, we will not discuss them further here. 

As must be evident from a previous section on classification, gas-liquid reactions can be carried out in a large number of reactor types. This is also true of other multiphase reactions in which a liquid phase is involved. For other reactions such as gas-solid, catalytic or noncatalytic, the choice of reactor is confined to a lesser number of variations. Therefore, although reactor choice is an important consideration for all reactions, particularly heterogeneous reactions, it is more so for gas-liquid, liquid-liquid, and slurry systems, all of which are widely used in industrial organic synthesis. We discuss below the cost minimization criteria for a rational choice of reactors for gas-liquid reactions. 

One of the current trends in development of both academic and industrial organic synthesis is orientation of chemists on using chlorine-free ecologically benign processes, based on direct methods of C-H functionalization of aromatic compoimds, avoiding halogenated starting materials or intermediates. 

Oxidation is one of the most important reactions in industrial organic synthesis [1-3] and can be carried out in both gas [4] and liquid [5,6] phases. Catalytic oxidation reactions in liquid phase were achieved in conditions of catalytic [5], photocatalytic [7], electrocatalytic [8], and photoelectrocatalytic [9] processes. At the same time, the new developments in the synthesis of materials led to the discovery of a large variety of catalysts and applications, including new catalysts for the liquid-phase oxidation reactions. A special interest in this sense was addressed to green and sustainable sources of oxidation [10]. 

Their use has, however, an important drawback that is related to the rather low surface areas and not easy preparation methods. But the recent achievements in the synthesis of metal-modified mesoporous silicas and development of new methods for the synthesis of oxides with higher surface areas diversified the number of catalysts and applications of mixed oxides as catalysts in liquid-phase oxidations. The performances recently reported opened new perspectives for the green and sustainable oxidation using such materials and extended the interest for the application of these reactions in industrial organic synthesis and water decontamination. Furthermore, coupling the photooxidation with Fenton and ozonation processes provides extremely attractive techniques in advanced oxidation processes for eliminating organic contaminants in wastewaters. 

Wohler s synthesis of urea (1828) and Kolbe s synthesis of acetic acid (1845) moved from the scientific scene s vis vitalis theory. Kolbe synthesis is presented here because of its historical importance and also as an extraordinary introduction to the ecological issues of industrial organic synthesis (Scheme 1.16). 

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