The bromination of all ten possible aminopicolines 1–10 was investigated. In general, the major brominated product was that corresponding to electrophilic attack at the sites para or ortho to the amino group.

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The kinetics and mechanism of the synthesis of the sulfonylguanidine 2 by reaction of the corresponding aniline, 1, with cyanamide have been investigated in aqueous acid solution. The reaction is acid-catalysed, but at low pH, where substantial protonation of 1 occurs, the dominant reaction occurring is a competing hydrolysis of cyanamide to urea. It is shown that reactions run under pH control in the region of pH 2 achieve close to maximum selectivity with respect to the desired guanidine formation, whilst still occurring at a practical rate.

ChemInform Abstract The bromination of all ten possible aminopicolines is investigated using 48% HBr/H2O2 at 70 rc C. In general, the major product is that corresponding to electrophilic attack at the sites para or ortho to the amino group. The aminobromopicolines are required for pharmaceutical and agrochemical screening.