Double-Action Herbicidal Ionic Liquids Based on Dicamba Esterquats with 4-CPA, 2,4-D, MCPA, MCPP, and Clopyralid Anions

Abstract

Herbicides such as (3,6-dichloro-2-methoxy)benzoic acid (dicamba), (4chloro-2-methylphenoxy)acetic acid (MCPA), (2,4-dichlorophenoxy)acetic acid (2,4-D), or (±)-2-(4-chloro-2-methylphenoxy)propionic acid (MCPP) are applied in the form of sodium, potassium, ammonium salts, or esters. Although esters are more biologically active, the downside is their high volatility, which is a hazard to neighboring dicotyledonous plants and spraying workers. Moreover, their commercial preparation requires the use of adjutants, which improve the wettability of the sprayed surfaces. Herbicidal ionic liquids (HILs) were introduced to overcome such drawbacks and proved to be more effective in terms of controlling weeds compared to currently applied commercial preparations. In this study, we investigated the concept of herbicidal ionic liquids that contained dicamba in a surface-active cation as an ester substituent as well as (4-chlorophenoxy)acetic acid (4-CPA), 2,4-D, MCPA, MCPP, and clopyralid as anions. The synthetized compounds were characterized in terms of surface and antimicrobial activity as well as herbicidal efficacy against garden cress (Lepidium sativum). Moreover, hydrolysis was performed using acidic, neutral, and alkaline treatments to check the conditions under which dicamba is released from the esterquat. It was revealed that the obtained HILs exhibited excellent surface properties manifested as a tendency to effectively interact with biological membranes at lower doses. This was observed as increased toxicity in comparison to reference herbicidal formulations during direct exposure; however, assessment of microbial activity in soil revealed that the ecotoxic effect was limited, most likely due to marginal mobility. Consequently, the tested HILs effectively reduced garden cress biomass production and were notably less volatile compared to commercial herbicides. Our findings present a sustainable concept of more effective usage of well-known herbicides with simultaneous reduction of the environmental burden by limiting the amount of chemicals intentionally introduced for agricultural purposes.

Transformation of Iodosulfuron-Methyl into Ionic Liquids Enables Elimination of Additional Surfactants in Commercial Formulations of Sulfonylureas

“…After the bacterial strains reached stationary phase, growth curves were plotted and then the rate of inhibition of microbial growth was calculated. The half maximal effective concentration (EC50·t −1 ) was determined according to the procedure described by Syguda et al [ 59 ].…”

Effect of Cation Sorption on 2,4-D Mobility of Herbicidal Ionic Liquids in Agricultural Soil Combined with Diversity of the Bacterial Community

“…Antimicrobial Activity Test. The procedure for assessing minimum inhibitory concentration (MIC) and minimum bactericidal or fungicidal concentration (MBC/MFC) was previously described in Syguda et al 23 The following species were used to evaluate the antimicrobial activity of the test substances: Pseudomonas putida KT2440, Pseudomonas aeruginosa PAO1, and Escherichia coli K-12 (Gram-negative bacteria); Staphylococcus aureus ATCC 6538 and Bacillus cereus ATCC 11778 (Gram-positive bacteria); and Candida albicans ATCC 10231 as a fungal species. The final test concentrations of tested compounds were 1000, 750, 500, 250, 100, 50, 10, and 1 mg/L.…”

Solubility Measurement and Data Correlation of 4-Chlorophenoxyacetic Acid in 13 Monosolvents at Temperatures from 283.15 to 328.15 K

“…For instance, the IEC value of the CS-CPA membrane is about twice that of the chitosan (CS) membrane . Moreover, it has been reported that 4-CPA can be used as a herbicide ionic liquid (HIL) to improve the herbicidal effect and serves as the sole source of carbon and energy of a new natural strain (36DCP) with the deepening of research in recent years. − …”