Bench chemist

In order to achieve the goals of making more efficient use of the information that is produced and of planning and performing better experiments, chemoinformatics will have to be more integrated into the daily work processes of the chemist, and into the work of the bench chemist. Certainly, many chemists still have to overcome high barriers to using the computer for assistance in the solution of their daily scientific problems. 

However, better use of spectral information for more rapid elucidation of the structure of a reaction product, or of a natural product that has just been isolated, requires the use of computer-assisted structure elucidation (CASE) systems. The CASE systems that exist now are far away from being routinely used by the bench chemist. More work has to go into their development. 

This does not have to be so Why not build an uninterrupted stream of information from the producer (the bench chemist) to the consumer (the reader of a journal or book, or the scientist that puts a query into a database) It is quite clear that the producers of information knows best what experiments were done, what observations were made, what results have been obtained. They should put this information into electronic laboratory books, augmented with spectral data (that they can obtain directly from the analytical laboratory). From this electronic repository aU other information sources -manuscripts, journals, books, databases - could be filled, clearly sometimes by manual selection, but not by changing data ... 

The actual catalyst is a complex formed from osmium tetroxide and a chiral ligand, e.g. dihydroquinine (DHQ) 9, dihydroquinidine (DHQD), Zj -dihydroqui-nine-phthalazine 10 or the respective dihydroquinidine derivative. The expensive and toxic osmium tetroxide is employed in small amounts only, together with a less expensive co-oxidant, e.g. potassium hexacyanoferrate(lll), which is used in stoichiometric quantities. The chiral ligand is also required in small amounts only. For the bench chemist, the procedure for the asymmetric fihydroxylation has been simplified with commercially available mixtures of reagents, e.g. AD-mix-a or AD-mix-/3, ° containing the appropriate cinchona alkaloid derivative ... 

As far as the bench-chemist is concerned, the following nonexhaustive list of points should be incorporated into the experimental plan ... 

There is no substitute for the chemist s intuition. The bench chemist should personally perform the primary analysis of the theoretical data and possibly the data generation itself, as long as the chemist understands that this method is not a miracle solution (and will not replace him or her). Ownership of the problem will often mean that the bench scientist is eating, sleeping and drinking the problem. This is the person who has the most insight into the problem and this is the person you want to look at the molecular graphics and the probe surfaces. 

Certainly biomolecular NMR is not the single method which is important for hit identification in pharmaceutical research. It is always a combination of techniques and a team effort that leads to a successful drug. This can involve biologists (basic understanding, assay development, bio-informatics), chemists (both bench chemists and modelers), screening specialists (HTS/natural products) and spectroscopists (X-ray, optical methods, surface plasmon resonance, NMR). 

Unfortunately, many reactions do not occur with quantitative conversion and in near absolute purity. The work-up and purification of most chemical processes probably takes up most of a bench chemists time. Therefore techniques that simplify and accelerate these operations not only free up valuable time, but allow greater creativity and increased levels of output. Here again, supported systems can be used to aid the chemist in the guise of scavengers, quenching agents and catch and release systems. 

Disadvantages. The discussion of the advantages of polymer adsorption was relative to solvent extraction. This same perspective will be used in the discussion of the disadvantages. Most analytical chemists are familiar with solvent extraction procedures using solvents that are readily available in the desired purity. When the solvents are not pure enough for direct use in trace analytical work, the purification procedures are usually ones that are familiar to most bench chemists and technicians. These advantages of solvent extraction are the disadvantages of polymer adsorption. 

The hydroformylation of alkenes generally has been considered to be an industrial reaction unavailable to a laboratory scale process. Usually bench chemists are neither willing nor able to carry out such a reaction, particularly at the high pressures (200 bar) necessary for the hydrocarbonylation reactions utilizing a cobalt catalyst. (Most of the previous literature reports pressures in atmospheres or pounds per square inch. All pressures in this chapter are reported in bars (SI) the relationship is 14.696 p.s.i. = 1 atm = 101 325 Pa = 1.013 25 bar.) However, hydroformylation reactions with rhodium require much lower pressures and related carbonylation reactions can be carried out at 1-10 bar. Furthermore, pressure equipment is available from a variety of suppliers and costs less than a routine IR instrument. Provided a suitable pressure room is available, even the high pressure reactions can be carried out safely and easily. The hydroformylation of cyclohexene to cyclohexanecarbaldehyde using a rhodium catalyst is an Organic Syntheses preparation (see Section 4.5.2.5). 

Such a program is more likely to be well received and generally accepted because it provides a mechanism for bench chemists to express their concerns, and to participate actively in the program. 

The involvement of bench chemists with well thought out protocols resulted in functional QA Plans for each section in the Bureau. 

But there are signs that simpler, less expensive LC/MS systems designed and priced for the general laboratory bench chemist, production facilities, and quality control laboratories may soon be possible. It remains to seen whether manufacturers will decide to produce these systems. Older MS systems have been purchased, attached to HPLC systems equipped with relatively inexpensive interfaces, and pressed into service for molecular weight determination as a 30,000 detector, indicating that the desire and need exists for general laboratory LC/MS systems. As prices continue to drop and technology advances work their way out of the research laboratories, the LC/MS will become a major tool for the forensic chemist whose separations must stand up in court, for the clinical chemist whose separations impact life and death, and for the food and environmental chemist whose efforts affect the food we eat, the water we drink, and the air we breathe. 

Five consecutive papers in Angew. Chem. recently described syntheses of the vancomycin aglycon. D. A. Evans and co-workers developed one route at Harvard [1, 2], while the other comes from K. C. Nicolaou s group at Scripps [3-5]. They represent an amalgamation of synthetic methodologies in schemes that took some of the most skillful bench chemists in academia years to execute. 

Several very useful books on the subject of chemical process development have been published.1 These have been written largely from the point of view of the bench chemist or chemical engineer. Emphasis in this collection of books is on the work needed to ensure that practical chemical reactions are created for scale-up, that the chemistry is understood, that the theory and mechanics needed to engineer scale-up are addressed, and that Safety, Environment and Food and Drug Administration requirements are met. 

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