Route/Process Design
In a technology-based chemical approach, it is important that the technology fits effectively with the chemical
route as a whole, and does not make the route any longer. For a chemical target, particularly if its
structure is complex, there may be many choices of route, each employing a different advanced technology in one or
more steps. It can be quite challenging which route(s) should warrant the most investigation. In a
large part this comes from having sufficient experience with the practise of the technologies involved.
A simple cost model-based selection is used as appropriate, built around expected step-yields, step-complexity and
raw materials contribution. The offering is slightly different depending on whether you are an end-user of the
chemical product concerned, or supplier of either the product or technology towards it.
An interesting area of process R&D concerns organometallic catalysis and the expense of the metals and ligands
concerned. A survey of academic research papers revealed that for rhodium-based homogeneous catalysts, an average
of 2.4 mol% is used. With rhodium prices at the time of writing at $US 200/gram, that equates at this catalyst
loading of a cost contribution by rhodium of $US 500/mole substrate used; clearly uneconomic for process-scale
work. However if the rhodium-catalyst loading can be reduced to 0.01 mol%, that reduces the metal cost
contribution to just about $US 2/mole substrate which is certainly very economic in most cases. That level of
loading is certainly achievable in examples of asymmetric hydrogenations, but it is not known whether that is
possible in some of the more elaborate reactions that rhodium complexes catalyse. The amounts (typically 1-10%) of
metal complexes used in academic research seems to be driven by convenience; so copper-based catalysts are likewise
used in the same range (though then the cost of the ligand is by far the major consideration). In organocatalysis,
interestingly, the amounts used in academic research frequently reach as much as 20 mol%. Thus one of the skills in
Process R&D is to identify the opportunities for minimisation of amounts of catalyst needed. This can often
require attention to such aspects as substrate purity, reaction kinetics and rates of addition that are not
considered at the research scale.
| For End-Users e.g. Pharmaceutical Company |
For Fine Chemical Technology Providers |
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| develop programmes for your own experimental resource | prepare proposals and present those to your customers | |
| assist placing programmes with appropriate external experimental service providers | manage resulting customer projects | |
| assess proposals received from fine-chemicals companies/technology suppliers so that they can be improved | compile project reports and recommend means to gain further business from the customer |
For supply and project management needs in clinical or pre-clinical phases of pharmaceutical development: contact ChemPharmaServe