Catalysts as auxiliary reagents

As outlined above, processes developed in the laboratory generally utilise raw materials dictated only by the chemistry required. Selection of processing aids such as catalysts, antifoams, etc. is often empirical depending on knowledge and experience of the process development chemist. These auxiliaries tend to get carried forward into scale-up, and, whilst their quantity may become modified in optimisation studies, it appears to be a characteristic of the process development exercise that their nature does not. Inefficiencies in the process therefore get carried through and even amplified, and realistic opportunities for waste minimisation are often overlooked. 

Of particular significance commercially is the area of AT-alkylation. Hiinig and Kiessel [3] first described the use of Ar,AT-diisopropylethylamine in the reaction of aniline with -butyl bromide to produce N,N di-n-buiy-laniline (1). 

This represented a significant improvement over previously reported methods, for example using tri- -butylphosphate as the alkylating agent gives 78% yield. 

The pyrrolidone ring can then be built onto the side chain to yield the selective herbicide fluorochloridone. 

2 Sensitive esterifications. The steric bulk and high proton affinity of Hiinig s Base make it particularly useful in enhancing the selectivity of certain esterification reactions. Benzyl salicylate is a particularly useful ester (5). 

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