Department of Chemical Technology, Poznan University of Technology, Poznan 60-965, Poland.
Department of Agronomy, Poznan University of Life Sciences, Poznan 60-637, Poland.
J Agric Food Chem. 2020 Nov 25;68(47):13661-13671. doi: 10.1021/acs.jafc.0c05850. Epub 2020 Nov 10.
A new family of bio-based herbicidal ionic liquids (HILs) has been synthesized starting from the renewable resource glycine betaine (a derivative of natural amino acids). After esterification, the obtained alkyl betainate bromides containing straight alkyl chains varying from ethyl to octadecyl were combined with a herbicidal anion from the sulfonylurea group (iodosulfuron-methyl). The melting points of the iodosulfuron-methyl-based salts were in a range from 51 to 99 °C, which allows their classification as ionic liquids (ILs). In addition, the new HILs exhibited good affinity for polar and semipolar organic solvents, such as DMSO, methanol, acetonitrile, acetone, and chloroform, while the presence of bulky organic cations reduced their solubility in water. The synthesized products turned out to be stable during storage at 25 °C for over 6 months; however, at 75 °C they underwent fast, progressive degradation and released volatile byproducts. The values of the logarithm of the octanol-water partition coefficient of ILs with alkyls longer than hexyl occurred in the "safe zone" (between 0 and 3); hence, the risk of their migration into groundwater after application or the possibility of their bioaccumulation in the environment is lower in comparison with the currently available commercial form (iodosulfuron-methyl sodium salt). Greenhouse studies confirmed a very high herbicidal efficacy for the obtained salts toward tested plants of oilseed rape, indicating that they may become an attractive replacement for the currently available sulfonylurea-based formulations.
已从可再生资源甘氨酸甜菜碱（天然氨基酸的衍生物）出发，合成了一系列新型生物基除草离子液体（HILs）。经过酯化反应，得到了一系列直链烷基甜菜碱溴盐，烷基链从乙基到十八烷基不等，然后与磺酰脲基团（碘甲磺隆甲酯）的除草阴离子结合。碘甲磺隆甲酯盐的熔点在 51 至 99°C 之间，可将其归类为离子液体（ILs）。此外，新的 HILs 对极性和非极性有机溶剂（如 DMSO、甲醇、乙腈、丙酮和氯仿）具有良好的亲和力，而大体积有机阳离子的存在降低了它们在水中的溶解度。合成的产物在 25°C 下储存超过 6 个月时表现出稳定；然而，在 75°C 下，它们会迅速、渐进地降解，并释放出挥发性副产物。烷基长度超过己基的 ILs 的辛醇-水分配系数的对数值落在“安全区”（0 到 3 之间）；因此，与目前可用的商业形式（碘甲磺隆甲酸钠）相比，它们在应用后迁移到地下水或在环境中生物累积的风险较低。温室研究证实，所获得的盐对测试的油菜等植物具有很高的除草效果，表明它们可能成为目前可用的磺酰脲类制剂的替代品。
