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环酯草醚合成工艺优化及嘧啶硫苯甲酸肟酯合成、活性的研究
论文作者:童鞋论文网  论文来源:www.txlunwenw.com  发布时间:2019/9/6 7:35:29  

摘要:目前除草剂的用量约占整个农药用量的一半,并随着人们安全意识的提高,在农业生产中更倾向于使用用量少及用药时间无要求、对后茬作物生长影响小的农药。以乙酰乳酸合成酶(ALS)为靶向的除草剂,活性高、广谱除草、对作物无伤害且对人和动物的伤害极低,因此引起人们的广泛关注。

在不同结构ALS抑制剂中,嘧啶氧(硫)苯甲酸类除草剂的合成最为简单,环酯草醚是以硫桥连接的嘧啶硫苯甲酸类新颖除草剂,是水稻苗后早期广谱除草剂。其生产工艺复杂、三废多,不利于其工艺的推广。本文以绿色制造为起点,制定合成路线,对其工艺进行优化。本文以3-硝基邻苯二甲酸为原料,经分子内缩合、Knoevenagel缩合反应、酸水解反应、还原内酯化反应、自由基硫代、双硫键还原及取代反应等反应步骤制得环酯草醚,最终产品总收率为51%,纯度为99%。相较于之前的合成路线,提高生产效率、降低产生三废及降低反应的操作难度,有利于其绿色制造。

由于环酯草醚的活性在其同类化合物中的活性不高,本文对其结构进行优化。以硫代水杨酸及醛类化合物为原料,通过对反应条件的优化,设计并合成了24种具有嘧啶硫苯甲酸肟酯类化合物新化合物。本文通过茎叶喷雾法、分子对接及酶促法,对24个化合物进行活性评价。研究表明,通过茎叶喷雾法发现,49a、49h、49i、49n、49o、49p、49t对稗草具有较好的抑制率,并且大部分化合物的活性要高于环酯草醚;通过分子对接,从微观结构上看出新化合物与ALS的氨基酸残基的作用方式,发现含F-取代(49d、49i、49j)、OH-取代(49n、49o)、NH2-取代(49p)的结构活性高于同类化合物,且所有化合物的活性都要高于环酯草醚;通过酶促法发现,49d、49i、49j、49n、49o、49p活性较好,供电子基有利于提高化合物的活性,3-取代的化合物活性较低,有14种新型化合物的活性都达到50%以上,双草醚对ALS抑制率为34%,环酯草醚对ALS的抑制率为18%,除49u、49x外,其他化合物活性都高于双草醚和环酯草醚。

Currently, herbicides account for about half usage of pesticides used. With the increasing concern of the safety issues, the herbicides with less dosage, less-persistent and degradability are preferred in agricultural production. Herbicides that targeting Acetolactate Synthase (ALS) attracted great attention in recent years,  since they exhited high activity,  broad herbicial spectrum, low toxicity to humans and animals and no harm to crops.

Among the different ALS inhibitors, pyrimidine oxy(thio)benzoic acid herbicides are the easiest to synthesize. Pyriftalid linked by sulfur bridge is a novel pyrimidine thiobenzoic acid herbicide, which was used as an early broad-spectrum herbicide after rice seedling. The Pyriftalid manufacturing process was complex and generated much waste, which significantly limited its wide application. The aim of this article was to develop a green and efficient manufacturing process of Pyriftalid. In this paper, 3-nitrophthalic acid was used as raw material to prepare Pyriftalid by reaction steps such as intramolecular condensation, Knoevenagel condensation reaction, acid hydrolysis reaction, reductive lactonization reaction, free radical thiogeneration, disulfide bond reduction and substitution reaction. The total yield of the product was 51% and the purity was 99%. Compared with the previous synthetic route, 3-methyl-7-mercaptophenylhydrazine was prepared by 3-methyl-7-nitrophthalide directly reacting with potassium thioacetate. Not only the purity and yield of the product was improved, but also the production efficiency was improved, the waste was reduced and the operation was simplifyed, which was beneficial for its green manufacturing.

Due to  the low activity of Pyriftalid among similar compounds, the structure of Pyriftalid was optimized in this paper. Thiosalicylic acid and aldehydes were used as raw material to design and prepare 24 new compounds with pyrimidine thiobenzoate under optimized reaction conditions. The activity of all new compounds was evaluated by foliar spray application test, molecular docking and enzyme catalysis. The activities of the most compounds were higher than Pyriftalid. The results of  the foliar spray application tests showed that 49a, 49h, 49i, 49n, 49o, 49p and 49t were excellent chemical herbicides for controlling Echinochloa crusgallis. Moreover, the activity of most compounds was higher than Pyriftalid. Molecular docking observed the interaction mode between the new compound and the residued amino acid of ALS from the microscopic. It was found that the ALS-49 complexes with F-substitutions (49d, 49i, 49j), OH-substituteds (49n, 49o) or NH2-substituteds (49p) were more stable than other similar compounds, and the activity of  all novel compounds was higher than Pyriftalid. The results of  enzyme catalysis suggested that the activity of 49d, 49i, 49j, 49n, 49o and 49p was higher than  other congeners. The electron donating groups were beneficial to improve the activity of the compounds and the activity of 3-substituted compounds were lower than others. The activity of 14 new compouds over 50%. The  ALS inhibition ratio of Pyriftalid  and Bispyribac-sodium was 18% and 34%, respectively, Which is lower than all compounds except  49u and 49x.

关键词:乙酰乳酸合成酶;环酯草醚;工艺优化;衍生物;活性评价

Acetolactate Synthase; Pyriftalid; Reaction Optimization; Derivate; Activity Evaluation

上一篇:基于表面等离子体激元的电磁超材料吸波器设计及增强吸收特性研究     下一篇:气道平滑肌通过生物力学交流促进网络形态自组装及异丙肾上腺素的作用效果研究
 
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