Chemical process development towards

In terms of environmental sustainability of catalytic reactions the development of synthetic processes towards the reduction of hazardous waste is one of the greatest challenges in modern chemistry. Among the many possibilities to achieve that goal, like the use of nontoxic ionic liquids or water as reaction solvent, the application of the mechanochemical methods, e.g. grinding and ball milling recently received much focus in chemical process development. ... 

Recently, we identified several novel types of Fe/aKG-DOs that catalyze the hydroxylation of free aliphatic amino acids, me hydroxy aliphatic amino acids have several chiral carbons and may be important as precursors and chiral auxiliaries in the chemical synthesis of other compoimds [10,11]. In this section, we describe these novel Fe/aKG-DOs and reviewed the homology of their amino acid sequences, catalytic characteristics, and process development toward their industrial applications. 

Because of the ovedapping roles of coal in industry, many of the technologies covered here have been developed for synthetic fuel appHcations, but they also have been used or have demonstrated potential for production of significant quantities of chemicals. The scope of an article on coal as a chemical source would not be complete without coverage of synfuel processes, but the focus will be on the chemical production potential of the processes, looking toward a future when coal again may become the principal feedstock for chemical production. 

AH cephalosporins found in nature (Tables 1 and 2) have the D-a-aminoadipic acid 7-acyl side chain (21). AH of these compounds can be classified as having rather low specific activity. A substantial amount of the early work in the cephalosporin area was unsuccessfiiHy directed toward replacing the aminoadipic acid side chain or modifying it appropriately by fermentation or enzymatic processes (6,22). A milestone ia the development of cephalosporins occurred in 1960 with the discovery of a practical chemical process to remove the side chain to afford 7-ACA (1) (1). Several related processes were subsequendy developed (22,23). The ready avaHabHity of 7-ACA opened the way to thousands of new semisynthetic cephalosporins. The cephalosporin stmcture offers more opportunities for chemical modification than does that of penicillins There are two side chains that especiaHy lend themselves to chemical manipulation the 7-acylamino and 3-acetoxymethyl substituents. 

The CCPS Taxonomy developed for this book is one step toward accumulating and collating equipment reliability data for the CPI. Ideally, it will be expanded and modified as more companies make chemical process equipment failure rates and reliability data available. We expect that CCPS will update this book and the CCPS generic data base as new information becomes available. The taxonomy may also require modification where experience shows it is needed. We would appreciate any contribution from readers to these ends. 

The Reichstein-Griissner process, developed in 1934, takes in all five chemical steps (hydrogenation, fermentative oxidation, acetonization, oxidation, and hydroly-sis/rearrangement) (Table 20.3). Over the course of the whole synthesis there are 17-20 different downstream processing steps, six solid-handling steps, and at least seven different solvent systems to handle. The overall yield is about 55%, and overall cycle time is around three days. Such values clearly suggest possible improvement in the process towards ascorbic acid. 

---