Rafał Giszter

Bis(ammonium) ionic liquids with herbicidal anions

The method of synthesis of the novel bis(ammonium) herbicidal ionic liquids with the cation containing two quaternary nitrogen atoms was described. New compounds, containing three structurally different linkers, were prepared via acid–base reaction between the corresponding bis(ammonium) hydroxides and herbicides in the form of free acids. In addition, phase transitions, thermal stability and solubility in common solvents were determined. The herbicidal efficacy was tested in greenhouse experiments, wherein test plants were lambsquarters (Chenopodium album L.) cornflower (Centaurea cyanus L.), white mustard (Sinapis alba L.) and winter rape (Brassica napus L.). The biological activity of the anion (2,4-D, MCPA, Mecoprop, Dicamba) in all new HILs was preserved. Moreover, the efficacy of some salts was several times higher when compared to commercial formulations.

Alkyl(C16, C18, C22)trimethylammonium-Based Herbicidal Ionic Liquids

In the framework of this study a synthesis methodology and characterization of long alkyl herbicidal ionic liquids (HILs) based on four commonly used herbicides (2,4-D, MCPA, MCPP, and dicamba) are presented. New HILs were obtained with high efficiency (>95%) using an acid-base reaction between herbicidal acids and hexadecyltrimethylammonium, octadecyltrimethylammonium, and behenyltrimethylammonium hydroxides in alcoholic medium. Among all synthesized salts, only three compounds comprising the MCPP anion were liquids at room temperature. Subsequently, the influence of both the alkyl chain length and the anion structure on their physicochemical properties (thermal decomposition profiles, solubility in 10 representative solvents, surface activity, density, viscosity, and refractive index) was determined. All HILs exhibited high thermal stability as well as surface activity; however, their solubility notably depended on both the length of the carbon chain and the structure of the anion. The herbicidal efficacy of the obtained salts was tested in greenhouse and field experiments. Greenhouse testing performed on common lambsquarters (Chenopodium album L.) and flixweed (Descurainia sophia L.) as test plants indicated that HILs were characterized by similar or higher efficacy compared to commercial herbicides. The results of field trials confirmed the high activity of HILs, particularly those containing phenoxyacids as anions (MCPA, 2,4-D, and MCPP).

Synthesis, Surface Properties and Biological Activity of Long Chain Ammonium Herbicidal Ionic Liquids

Herbicidal ionic liquids exhibit many advantages compared to conventional chemical plant protection agents, which allow for a reduction of the herbicide dose per hectare and decrease of toxicity. Popular herbicides, such as 4-chloro-2-methylphenoxyacetic (MCPA) or 2,4-dichlorophenoxyacetic (2,4-D) acids, can be modified by reaction with long chain ammonium cations in order to obtain novel forms. The aim of this study was to present an alternative method for the synthesis of herbicidal ionic liquids based on a natural cation known as Ethoquad C/12 and to analyze the physicochemical properties and herbicidal activity of the obtained products. New ionic liquids comprising MCPA and 2,4-D as anions were obtained and their chemical as well as thermal stability were evaluated. Furthermore, their biological and surface activity were investigated. The obtained results confirmed that the herbicidal activity has been preserved.