Bench synthetic procedure

After medicinal chemists nominate a compound as a developmental target, process chemists initiate process research and development activities. As described elsewhere in the book, process research chemists carefully analyze the medicinal chemistry route and make suitable modifications. Chemical process development converts a bench synthetic procedure into a safe, robust, and economically viable process suitable for manufacturing. The concept of process robustness is described as follows ... 

We have reported a simple, green, bench top, economical and environmentally benign room temperature synthesis of MSe (M=Cd or Zn) nanoparticles using starch, PVA and PVP as passivating agents. The whole process is a redox reaction with selenium acting as the oxidant and MSe as the reduction product. An entire "green" chemistry was explored in this synthetic procedure and it is reproducible. The optical spectroscopy showed that all the particles are blue shifted from the bulk band gap clearly due to quantum confinement. Starch capped CdSe nanoparticles showed the presence of monodispersed spherical... 

When a synthetic procedure is run for the first time at the bench, a satisfactory result is obtained only rarely. If the purpose of the experiment was to prepare a limited quantity, e.g. for spectroscopic characterization or for toxicological screening, it is probably of minor importance if the yield was low. If, on the other hand, the purpose was to check a new method, or to run a pilot experiment for larger-scale preparation, a poor yield is often a starting point for tedious work to develop the procedure. 

With the advances in pro-catalyst design that have been witnessed over the last decade or so, the transition-metal-catalysed alkene metathesis reaction has now become a practical procedure that can be utilised by the chemist at the bench. Undeniably, this has added a new dimension to the repertoire of synthetic organic chemistry as it facilitates disconnections that, pre-metathesis, simply would not have been considered. Take, for example, a macro-cyclic amide where the normal disconnection would be at the amide. Now, with the ready reduction of alkenes to alkanes, a ring-closing diene metathesis (RCM), followed by hydrogenation, becomes an alternative disconnection. And, when one considers that any of the C—C linkages could be established in such a manner, the power of the RCM disconnection becomes obvious. 

One example of a miniaturized LC/MS strategy is the use of 96-well sample plates (Kaye et al., 1996) for extraction. This sample extraction procedure combines batch sample processing within a miniaturized format. Increased sensitivity and decreased volume advances have fostered a new wave of scale-down models. Experiments that were formerly performed at the bench are, instead, performed at the microliter scale in the batch mode. For example, synthetic process research was traditionally performed manually with apparatus at the milliliter level. This approach involves the testing of a range of synthetic conditions for optimum yield and minimum impurity production. Now, process research conditions are tested in microliter levels to produce information on purity and structure (Rourick et al., 1996). This strategy requires fewer reagents and accelerates the evaluation of a wider range of conditions in a shorter time. Another example includes the direct analysis of samples from cell culture experiments (Kerns et al., 1997). 

Simulators are developed primarily for the procedure(s) they are designed to emulate. Surgical simulators can include animal models, cadavers, synthetic and tissue-based bench models, computer/web-based simulators, video box trainers, web-based interface simulators, VR (or computer driven) part-task trainers, VR simulators that can allow the user to mimic an entire surgical procedure (whole-task trainers), hybrid simulators... 

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