Acid- and Base-Mediated Hydrolysis of Dichloroacetamide Herbicide Safeners.
Acid- and Base-Mediated Hydrolysis of Dichloroacetamide Herbicide Safeners.
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DOI：
10.1021/acs.est.1c05958
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发表时间：
2022-01-04
影响因子：
11.4
通讯作者：
Cwiertny DM
中科院分区：
文献类型：
--
作者：
McFadden ME;Patterson EV;Reber KP;Gilbert IW;Sivey JD;LeFevre GH;Cwiertny DM
安全剂广泛用于商业除草剂配方中。虽然安全剂被规定为惰性成分，但它们的一些转化产物具有增强的生物活性。在这里，为了填补我们对安全剂环境命运的理解空白，我们确定了与二氯乙酰胺安全剂AD-67、苯恶唑、二氯胺和呋喃唑酸和碱介导的水解相关的速率常数和转化产物。酸（HCl）和碱（NaOH）介导的二氯乙酰胺水解的二阶速率常数（分别为2.8 × 10-3至0.46和0.3-500 M-1 h-1），在许多情况下（8个中的5个）比氯乙酰胺除草剂共制剂的二级速率常数要大。尤其值得一提的是，苯恶草胺的碱介导水解速率常数比其活性成分共制剂s -异甲草胺的水解速率常数大2个数量级。在环中性pH下，只有苯氧苄啶发生了明显的水解（5.3 × 10-4 h-1），而在石灰-苏打软化的高pH条件下，苯氧苄啶的半衰期为13 h，这与水处理过程中的部分转化时间尺度一致。基于Orbitrap LC-MS /MS对二氯乙酰胺水解产物混合物的分析，我们提出了主要产物的结构和依赖于体系pH和化合物结构的三种不同的机制途径。这些包括碱介导的酰胺裂解，酸介导的酰胺裂解和酸介导的恶唑烷开环。总的来说，这项工作将有助于确定水解有助于二氯乙酰胺转化的体系，同时也强调了二氯乙酰胺及其活性氯乙酰胺共聚物的反应性的重要差异。二氯乙酰胺安全剂广泛存在于地表水中。我们展示了它们在自然和工程系统中的水解，并确定了对生态系统和人类健康有潜在风险的产品。
Safeners are used extensively in commercial herbicide formulations. Although safeners are regulated as inert ingredients, some of their transformation products have enhanced biological activity. Here, to fill gaps in our understanding of safener environmental fate, we determined rate constants and transformation products associated with the acid- and base-mediated hydrolysis of dichloroacetamide safeners AD-67, benoxacor, dichlormid, and furilazole. Second-order rate constants for acid- (HCl) and base-mediated (NaOH) dichloroacetamide hydrolysis (2.8 × 10–3 to 0.46 and 0.3–500 M–1 h–1, respectively) were, in many cases (5 of 8), greater than those reported for their chloroacetamide herbicide co-formulants. In particular, the rate constant for base-mediated hydrolysis of benoxacor was 2 orders of magnitude greater than that of its active ingredient co-formulant, S-metolachlor. At circumneutral pH, only benoxacor underwent appreciable hydrolysis (5.3 × 10–4 h–1), and under high-pH conditions representative of lime-soda softening, benoxacor’s half-life was 13 h—a timescale consistent with partial transformation during water treatment. Based on Orbitrap LC–MS/MS analysis of dichloroacetamide hydrolysis product mixtures, we propose structures for major products and three distinct mechanistic pathways that depend on the system pH and compound structure. These include base-mediated amide cleavage, acid-mediated amide cleavage, and acid-mediated oxazolidine ring opening. Collectively, this work will help to identify systems in which hydrolysis contributes to the transformation of dichloroacetamides, while also highlighting important differences in the reactivity of dichloroacetamides and their active chloroacetamide co-formulants. Dichloroacetamide safeners are widely present in surface waters. We demonstrate their hydrolysis in natural and engineered systems and identify products of potential risk to the ecosystem and human health.
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影响因子：
6.9
作者：
Acharya, Saraswati Poudel;Johnson, Jacob;Weidhaas, Jennifer
通讯作者：
Weidhaas, Jennifer
DOI：
10.1073/pnas.042105199
发表时间：
2002-04-16
影响因子：
11.1
作者：
Gan, JY;Wang, QQ;Jury, WA
通讯作者：
Jury, WA
影响因子：
7.3
作者：
La, Daniel S.;Belzile, Julie;Harmanget, Jean-Christophe
通讯作者：
Harmanget, Jean-Christophe
影响因子：
10.9
作者：
Klarich, Kathryn L.;Pflug, Nicholas C.;LeFevre, Gregory H.
通讯作者：
LeFevre, Gregory H.
DOI：
10.6028/jres.027.005
发表时间：
1941-08-01
影响因子：
--
作者：
Hubbard, D;Hamilton, EH
通讯作者：
Hamilton, EH