Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, 60-965 Poznań, Poland.
Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, 60-965 Poznań, Poland.
Ecotoxicol Environ Saf. 2021 Jan 15;208:111595. doi: 10.1016/j.ecoenv.2020.111595. Epub 2020 Nov 26.
Modern agricultural practices are often based on the use of mixtures of specific herbicides to achieve efficient crop protection. The major drawbacks of commercial herbicidal formulations include the necessity to incorporate toxic surfactants and high volatility of active substances. Transformation of herbicides into herbicidal ionic liquids (HILs) seems to be a promising alternative which allows to almost completely reduce volatility due to ionic interactions. In the scope of this research, we transformed (2-methyl-4-chlorophenoxy)acetic acid (MCPA) into a quaternary ester (esterquat) with the use of derivatives of 2-dimethylaminoethanol. The obtained esterquats were later coupled with (±)-2-(4-chloro-2-methylphenoxy)propionic acid (MCPP) in the form of an anion. The combination of MCPA and MCPA is commonly applied in the UK, EU countries and also in the USA to increase the spectrum of targeted weed species. In the framework of this study, novel HILs with an esterquat moiety incorporating a long alkyl chain (C, C, C, C, C, C) were prepared and characterized in terms of basic physicochemical properties (solubility and volatility) as well as biodegradability. Their phytotoxicity was assessed towards cornflower (Centaurea cyanus) as a model weed and maize (Zea mays) as a crop plant. The presence of the esterquat cation contributed to satisfactory solubility in water and other low polar solvents, which eliminates the need to add exogenous adjuvants. Further experiments indicated that the tested HILs stimulated the germination stage of maize and maintained high herbicidal activity towards cornflower. No significant differences in terms of properties were observed in case of HILs which included alkyl substituents with an odd number of carbon atoms. Future studies should be focused on structural modifications in order to improve the biodegradability as well as field studies for evaluation of commercial applications.
现代农业实践通常基于使用特定除草剂的混合物来实现高效的作物保护。商业除草剂配方的主要缺点包括必须加入有毒的表面活性剂和活性物质的高挥发性。将除草剂转化为除草剂离子液体 (HIL) 似乎是一种很有前途的替代方法，因为它可以几乎完全由于离子相互作用而降低挥发性。在本研究范围内，我们使用 2-二甲氨基乙醇的衍生物将（2-甲基-4-氯苯氧基）乙酸（MCPA）转化为季铵酯（esterquat）。随后，将得到的 esterquat 与（±）-2-（4-氯-2-甲基苯氧基）丙酸（MCPP）以阴离子的形式偶联。MCPA 和 MCPA 的组合在英国、欧盟国家和美国通常用于增加目标杂草物种的范围。在本研究框架内，制备了具有长烷基链（C、C、C、C、C、C）的季铵酯部分的新型 HIL，并对其基本物理化学性质（溶解度和挥发性）以及生物降解性进行了表征。它们对矢车菊（Centaurea cyanus）作为模式杂草和玉米（Zea mays）作为作物植物的植物毒性进行了评估。酯基季铵阳离子的存在有助于在水中和其他低极性溶剂中具有令人满意的溶解度，从而消除了添加外源助剂的需要。进一步的实验表明，测试的 HIL 刺激了玉米的萌发阶段，并对矢车菊保持了高除草活性。在包含奇数个碳原子的烷基取代基的 HIL 中，观察到性质没有明显差异。未来的研究应集中于结构修饰，以提高生物降解性以及田间研究，以评估商业应用。
