The aqueous photolysis of triclopyr

Abstract

The aqueous photolysis of triclopyr was examined in both pH 7‐buffered water and natural river water under artificial lights and midsummer sunlight (40°N latitude). The pseudo‐first‐order half‐lives in pH 7‐buffered water and natural river water averaged 0.5 and 1.3 d, respectively, at 25°C. Diffuse mercury lamps and midsummer sunlight produced similar rates of triclopyr decay and photoproduct distribution for a given solution. The photolysis of untreated river water produced a significantly different distribution of photoproducts compared to sterile, pH 7‐buffered water. The photolysis of triclopyr in river water generated oxamic acid as the major photoproduct and a number of other low‐molecular‐weight carboxylic acids as minor products. Photolysis in sterile, pH 7‐buffered water produced 5‐chloro‐3,6‐dihydroxy‐2‐pyridinyloxyacetic acid as the major photoproduct, with minor amounts of oxamic acid and other low‐molecular‐weight acids.

RESEARCH NOTE: Ozone Degradation Of Selected Non-Agricultural Herbicides

“…Such poor removals, at similar herbicide and ozone concentrations, are comparable to those reported for atrazine (Foster et al, 1992;Xiong and Graham, 19921. However, imazapyr and triclopyr both have lower affinities for particulate interactions and much greater solubilities than either atrazine or simazine (Neary et al ., 1993). Consequently, although the photodegradation rates of both imazapyr and triclopyr are reported to be rapid (Woodburn et al, 1993;Mallipudi et al ., 19911, if they are applied as replacements for the triazines, the potential of imazapyr and triclopyr to contaminate potable water supplies might be significantly greater.…”

Photolytic and microbial degradation of 3,5,6‐trichloro‐2‐pyridinol

“…There are two reports regarding photodegradation pathways of chlorinated pyridines; they suggest the occurrence of hydrolytic dechlorination. Smith [1] speculated that TCP undergoes photodehalogenation with the formation of a series of diols, triols, and tetraols; Woodburn et al [14] reported that aqueous photolysis of the herbicide triclopyr (pH 7) produced 5‐chloro‐3, 6‐dihydroxy‐2‐pyridinyloxyacetic acid as the major product and other low‐molecular‐weight acids.…”

Sensitive voltammetric method for rapid determination of pyridine herbicide triclopyr on bare boron-doped diamond electrode

“…(1)) oxidize further the products of TCP oxidation. A number of studies on photocatalytic degradation of related chloromethylphenoxy herbicides, chloropyridines [56,57], and their derivatives including triclopyr [58][59][60] and clopyralid [61] revealed that the electrophilic attack of HO on the pyridine ring may lead to release of the chloride [56,60] and/or to formation of hydroxypyridines, and further to quinonic and ketonic structures [39,57], or even to ring opening [39]. Electrochemical incineration of chloromethylphenoxy herbicides using anodic oxidation at BDD anode by means of HO leads to formation of corresponding phenol derivatives and their further hydroxylation with benzoquinones as byproducts of HO iniciated oxidation [39].…”