Adjustment of the Structure of the Simplest Amino Acid Present in Nature—Glycine, toward More Environmentally Friendly Ionic Forms of Phenoxypropionate-Based Herbicides

The use of chemicals for various purposes in agriculture has numerous consequences, such as the contamination of ecosystems. Thus, nowadays it is perceived that their development should adhere to the principles of green chemistry elaborated by Paul Anastas. Consequently, to create more environment-friendly herbicides, we elaborated a ‘green’ synthesis method of a series of ionic liquids (ILs) containing cations derived from glycine. The appropriately modified cations were combined with an anion from the group of phenoxy acids, commonly known as 2,4-DP. The products were obtained with high yields, and subsequently, their properties, such as density, viscosity and solubility, were thoroughly examined to elucidate existing structure–property relationships. All ILs were liquids at room temperature, which enabled the elimination of some serious issues associated with solid active forms, such as the polymorphism or precipitation of an active ingredient from spray solution. Additionally, the synthesized compounds were tested under greenhouse conditions, which allowed an assessment of their effectiveness in regulating the growth of oilseed rape, selected as a model dicotyledonous plant. The product comprising a dodecyl chain exhibited the greatest reduction in the fresh weight of plants, significantly surpassing not only a commercially used reference herbicide but also the potassium salt of 2,4-DP

Comprehensive Ecotoxicity Studies on Quaternary Ammonium Salts Synthesized from Vitamin B₃ Supported by QSAR Calculations

Lately, ionic forms (namely, quaternary ammonium salts, QASs) of nicotinamide, widely known as vitamin B3, are gaining popularity in the sectors developing novel pharmaceuticals and agrochemicals. However, the direct influence of these unique QASs on the development of various terrestrial plants, as well as other organisms, remains unknown. Therefore, three compounds comprising short, medium, and long alkyl chains in N-alkylnicotinamide were selected for phytotoxicity analyses, which were conducted on representative dicotyledonous (white mustard) and monocotyledonous (sorghum) plants. The study allowed the determination of the impact of compounds on the germination capacity as well as on the development of roots and stems of the tested plants. Interestingly, independently of the length of the alkyl chain or plant species, all QASs were established as non-phytotoxic. In addition, QSAR simulations, performed using the EPI Suite™ program pack, allowed the determination of the products’ potential toxicity toward fish, green algae, and daphnids along with the susceptibility to biodegradation. The obtained nicotinamide derivative with the shortest chain (butyl) can be considered practically non-toxic according to GHS criteria, whereas salts with medium (decyl) and longest (hexadecyl) substituent were included in the ‘acute II’ toxicity class. These findings were supported by the results of the toxicity tests performed on the model aquatic plant Lemna minor. It should be stressed that all synthesized salts exhibit not only a lack of potential for bioaccumulation but also lower toxicity than their fully synthetic analogs

Synthesis and efficacy of herbicidal ionic liquids with chlorsulfuron as the anion

In the framework of this research, four new herbicidal ionic liquids (HILs) comprising chlorsulfuron as the anion were synthesized and characterized. The new salts with chlorsulfuron contained the following cations: tetramethylammonium, didecyldimethylammonium, benzyltrimethylammonium and cholinium. All products were obtained with high yields exceeding 90% via acid–base reaction or ion exchange reaction, by the use of environment-friendly solvents. The structures of all synthesized HILs were confirmed by FT-IR, 1H NMR and 13C NMR analyses. Their efficacy against weeds has been studied under field conditions in fiber flax. All HILs showed herbicidal activity but efficiency was highly dependent on the type of cation and weed species. There were no statistically significant differences in the effectiveness of HILs toward common lambsquarters compared to the reference herbicide, except for salt with cholinium cation that showed significantly lower efficiency. As regards barnyard grass control, all HILs exhibited significantly lower efficacy than that of the reference herbicide, except for didecyldimethylammonium salt that showed similar activity. The synthesized products did not cause damage to flax plants. The obtained results confirmed that the herbicidal effectiveness of the active ingredient (chlorsulfuron) in the form of an ionic liquid can be adjusted by the selection of an appropriate cation in the synthesis

Removal of herbicidal ionic liquids by electrochemical advanced oxidation processes combined with biological treatment

International audienceRecently a new group of ionic liquids (ILs) with herbicidal properties has been proposed for use in agriculture. Owing to the design of specific physicochemical properties, this group, referred to as herbicidal ionic liquids (HILs), allows for reducing herbicide field doses. Several ILs comprising phenoxy herbicides as anions and quaternary ammonium cations have been synthesized and tested under greenhouse and field conditions. However, since they are to be introduced into the environment, appropriate treatment technologies should be developed in order to ensure their proper removal and avoid possible contamination. In this study, didecyldimethylammonium (4-chloro-2-methylphenoxy) acetate was selected as a model HIL to evaluate the efficiency of a hybrid treatment method. Electrochemical oxidation or electro-Fenton was considered as a pretreatment step, whereas biodegradation was selected as the secondary treatment method. Both processes were carried out in current mode, at 10 mA with carbon felt as working electrode. The efficiency of degradation, oxidation and mineralization was evaluated after 6 h. Both processes decreased the total organic carbon and chemical oxygen demand (COD) values and increased the biochemical oxygen demand (BOD5) on the COD ratio to a value close to 0.4, showing that the electrolyzed solutions can be considered as 'readily biodegradable.

Pharmacokinetic profile of 1-methylnicotinamide nitrate in rats

Treatment with 1-methylnicotinamide (MNA), a major metabolite of nicotinamide, exerts antithrombotic, anti-inflammatory, and vasoprotective effects. Yet, pharmacokinetic (PK) profile of MNA has not been fully characterized. In the present work, we analyze the PK profile of the MNA given as a nitrate (MNANO3) in comparison to nitrite (MNANO2) or chloride (MNACl) in rats. The bioavailability of MNA administered as MNANO3 equaled 22.4% as compared to MNANO2 or MNACl (9.2% and 9.1%, respectively). Moreover, in single-pass intestinal perfusion experiments, effective permeability of MNA given as MNANO3 was higher as compared to MNA administered as MNANO2 or MNACl. In turn, tmax was the shortest and Cmax the highest (0.22 h and 56.65μM) for intragastrically administered MNANO2 comparing to MNANO3 (1.92 h, 21.74μM) or MNACl (0.63 h, 16.13μM). Transfer constant between central and peripheral compartments (kcp) and volume of distribution (Vss) for MNANO3 (0.33 h-1 and 1.96 L/kg) were higher as compared to MNANO2 or MNACl (0.11 h-1, 0.08 h-1 for kcp and 1.05 L/kg, 0.76 L/kg for Vss, respectively). In conclusion, we characterized PK profile of MNA and demonstrated that nitrate ion augmented bioavailability and favorably modified PK profile of MNA. Furthermore, given vasoprotective properties of MNA as well as nitrate, MNANO3 represents a bifunctional compound

Bioherbicidal Ionic Liquids

This study presents the properties of a new group of ionic liquids (ILs) based on various cations and pelargonic acid, a natural nonselective herbicide. The obtained bio-ILs were obtained with high yield (>92%) using a metathesis reaction or neutralization of quaternary ammonium hydroxides and characterized in terms of physicochemical properties. Tests under greenhouse conditions confirmed the superior herbicidal activity of ILs compared to pure pelargonic acid, especially against white mustard (5–10-fold higher efficacy of ILs). Further studies under field conditions revealed that tetrabutylammonium, benzalkonium, and oleyltrimethylammonium pelargonates exhibited the highest efficiency (50.5%, 49.5%, and 46.7%, respectively) at an approximately 3-fold lower dose of pelargonic acid (2.72 kg per 1 ha) compared to that used in commercial products (8–11 kg per 1 ha). This allows classification of the synthesized ILs as bioherbicidal ionic liquids (bio-HILs). In addition to bio-HILs, two new auxins were also obtained. Evaluation of antimicrobial activity indicated that the most potent effect was observed in the case of salts with oleyltrimethylammonium and tallowtrimethylammonium cations [minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) values lower by 2 orders of magnitude compared to pelargonic acid]. The fundamental influence of the cation was also observed during biodegradability assay, as the results varied from 0% to 85% (the highest biodegradability was observed in the case of dodecylbetainium and tetrabutylammonium pelargonates). The computational data suggested that biodegradation efficiency seems to be influenced by the interactions between the cation and the anion. The performed toxicity tests allowed classification of the obtained bio-HILs as category V [di­(hydrogenated tallow)­dimethylammonium pelargonate] or category IV compounds against rats

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)

Metsulfuron-Methyl-Based Herbicidal Ionic Liquids

Ten sulfonylurea-based herbicidal ionic liquids (HILs) were prepared by combining the metsulfuron-methyl anion with various cation types including quaternary ammonium ([bis­(2-hydroxyethyl)­methyloleylammonium]⁺, [2-hydroxyethyltrimethylammonium]⁺), pyridinium ([1-dodecylpyridinium]⁺), piperidinium ([1-methyl-1-propylpiperidinium]⁺), imidazolium ([1-allyl-3-methylimidazolium]⁺, [1-butyl-3-methylimidazolium]⁺), pyrrolidinium ([1-butyl-1-methylpyrrolidinium]⁺), morpholinium ([4-decyl-4-methylmorpholinium]⁺), and phosphonium ([trihexyltetradecylphosphonium]⁺ and [tetrabutylphosphonium]⁺). Their herbicidal efficacy was studied in both greenhouse tests and field trials. Preliminary results for the greenhouse tests showed at least twice the activity for all HILs when compared to the activity of commercial Galmet 20 SG, with HILs with phosphonium cations being the most effective. The results of two-year field studies showed significantly less enhancement of activity than observed in the greenhouse; nonetheless, it was found that the herbicidal efficacy was higher than that of the commercial analog, and efficacy varied depending on the plant species

Glyphosate-Based Herbicidal Ionic Liquids with Increased Efficacy

Eight new glyphosate-based herbicidal ionic liquids (HILs), containing both mono- and dianions of glyphosate (benzalkonium glyphosate, bis­(2-hydroxyethyl)­cocomethylammonium glyphosate, oleylmethylbis­(2-hydroxyethyl)­ammonium glyphosate, didecyldimethylammonium glyphosate, di­(hydrogenated tallow)­dimethylammonium glyphosate, 4-decyl-4-ethylmorpholinium glyphosate, di­(benzalkonium) glyphosate, and di­(bis­(2-hydroxyethyl)­cocomethylammonium) glyphosate) were prepared via acid–base reaction between the corresponding ammonium hydroxides (some premade) and glyphosate free acid. The transformation of glyphosate free acid into ionic liquids led to an elimination of melting points in all but one compound and significant change in solubilities. All HILs exhibited higher thermal stability than glyphosate free acid. Greenhouse testing indicated that while at a higher application rate of 360 g/ha the efficacy of all the HILs was comparable to the commercial herbicide control, at a lower application rate of 180 g/ha, the efficacy of all HILs was as much as two and a half to three times higher when compared to the commercial formulation, and the dianionic glyphosates were the most effective. In field trials, all but one of the tested HILs demonstrated excellent efficacy. Laboratory regrowth tests established that the ionic liquids of glyphosate are efficiently translocated to rhizomes preventing the regrowth of plants