ABSTRACT
This chapter discusses the solubility properties, partition coefficients, pKas, hydrolytic and chemical stability, spectroscopic data, and chromatographic data of the five imidazolinone herbicides — imazapyr, imazamethabenz-methyl, imazethapyr, imazaquin, and AC 263,222 — the structures. The water solubility and vapor pressure of the imidazolinone carboxylic acids are low, whereas the octanol-water partition coefficients are pH dependent. At pH 4, the imidazolinone carboxylic acids are neutral and therefore lipophilic, whereas at pH 7 the carboxylic acids are ionized. The hydrolytic stability of the imidazolinone ring is pH dependent. At environmentally relevant PHS and temperatures, hydrolysis is very slow. Nicotinic acid esters move faster than nicotinic acid esters upon chromatography on silica gel thin-layer chromatography plates. This behavior is in agreement with reduced interaction with the silica gel due to intramolecular hydrogen bonding between the imidazolinone hydrogen and the pyridine nitrogen.
