Abstract Auxinic herbicides are widely used to control broadleaf weeds in cereal crop fields due to their excellent herbicidal activities. However, volatile drifting caused by their high vapor pressures is a great threat to neighbouring susceptible crops and environment and severely limits auxinic herbicide applications. In this study, a series of auxinic herbicide dimers were synthesized using 2,4-D, dicamba and MCPA as monomers to reduce their vapor pressures. The results showed that all of the dimers significantly reduced volatilities due to larger molecular weight. The dimers linked with two ester bonds had 2-fold higher herbicidal efficacies than their corresponding monomers in filed experiments. The dimers linked with amide bonds appeared to function as contact action and systemic action herbicides. The dimers, 3a-2(ethane-1,2-diylbis (2-(2,4-dichlorophenoxy)acetate)), 3a-4(2-((2-(2,4-dichlorophenoxy)acetyl)thio)ethyl 2-(2,4-dichlorophenoxy)acetate), 3b-2(ethane-1,2-diylbis(2-(4-chloro-2-methylphenoxy)acetate)) and 3c-2(ethane-1,2-diylbis(3,6-dichloro-2-methoxybenzoate)) significantly increased the efficacies and reduced volatilities, thus could be developed as potential novel postemergence herbicides.

中文翻译：

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合成的二聚体增加了除草活性，同时降低了挥发性

摘要 生长素类除草剂因其优异的除草活性而被广泛用于防治谷类作物领域的阔叶杂草。然而，由它们的高蒸气压引起的挥发性漂移对邻近的易感作物和环境构成巨大威胁，并严重限制了生长素类除草剂的应用。在这项研究中，使用 2,4-D、麦草畏和 MCPA 作为单体合成了一系列生长素除草剂二聚体，以降低它们的蒸气压。结果表明，由于较大的分子量，所有二聚体都显着降低了挥发性。在现场实验中，与两个酯键连接的二聚体的除草效果比其相应的单体高 2 倍。与酰胺键连接的二聚体似乎起到接触作用和内吸作用的除草剂的作用。二聚体，3a-2(乙烷-1,2-二基双(2-(2,