In the mid-1980’s, I invested my first 4 years learning to be a process chemist in agricultural process development. Half of that time, I worked on breakthroughs in process improvement for processes that reacted sodium trichloropyridinate with various electrophiles that produced products with sales in the hundreds of millions of dollars per year.
These processes are well documented in patents that have long since expired. They were almost all solvent-free PTC processes in which the electrophile (usually an alkyl halide or phosphoryl halide) was liquid and served as the solvent and/or the product was a liquid at the reaction temperature and became the solvent as the reaction progressed.
That appears to be the case in the reaction shown in the diagram.
Based on the procedure reported, this appears to be a solid-liquid PTC reaction. The water content in the sodium trichloropyridinate was not disclosed and that is often an important process parameter to control and monitor.
The phase-transfer catalyst was tetrabutylammonium bromide and one can assume that, in addition to the quat serving as a phase-transfer catalyst to transfer the trichloropyridinate anion into the organic phase, the bromide also likely served to form 2-butoxyethyl bromoacetate in situ which is more reactive than the chloro derivative. Since this is very likely an I-Reaction, the difference between the reactivity of the bromomethyl group and the chloromethyl group should be significant.
Some sodium bicarbonate was added presumably to avoid acidification of the reaction mixture, but maybe also to control moisture content. The NaCl salt byproduct could also serve to control moisture content to some degree.
The reaction was monitored by GC and was run until the limiting reactant was present in less than 1%. Yield loss was likely due to the extensive workup procedure reported that achieved 99% purity of the product.
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