2,4-滴异辛酯与2,4-滴丁酯室内除草生物活性对比

采用温室盆栽生物测定法, 对比测定了2,4-滴异辛酯和2, 4-滴丁酯茎叶处理对播娘蒿、荠菜、苘麻、反枝苋和土壤处理对茼麻、反枝苋的生物活性.结果表明,2,4-滴异辛酯施药后杂草的受害症状、除草效果均与2,4-滴丁酯相似,且二者茎叶处理活性均明显高于土壤处理活性.2,4-滴异辛酯和2,4-滴丁酯都表现出茎叶处理对反枝苋活性最高,EC50值分别为16.74和11.86 g a.i./hm2;其次为苘麻,EC50值分别为30.23和30.51 g a.i./hm2;对播娘蒿、荠菜的EC50值为89.18～128.56 g a.i./hm2.二者土壤处理对反枝苋、苘麻的EC50值较低,2,4-滴异辛酯处理分别为139.04和136.10 g a.i./hm2,2,4-滴丁酯处理分别为189.91和201.23 g a.i./hm2.     

硫酸氢钠催化合成2,4-滴丁酯

研究了在硫酸氢钠催化条件下,以2,4-二氯苯氧乙酸和正丁醇为原料合成除草剂2,4-二氯苯氧乙酸正丁酯的方法。考察了醇酸摩尔比、反应时间和催化剂用量等因素对反应的影响。确定其最佳的反应条件为:酸醇摩尔比为:1∶5,回流反应2.0 h,催化剂用量为0.3 g(基于0.1 mol的2,4-二氯苯氧乙酸),在此条件下酯化率达98.3%。本实验操作方便,反应条件温和,产品纯度和收率较高,避免了浓硫酸催化的种种缺点,具有工业化应用前景。     

除草剂2,4-滴微生物降解研究进展

高浓度2,4-滴是一种合成激素类除草剂,可有效防除阔叶杂草,微生物降解是其在环境中的主要代谢途径。综述了2,4-滴的除草作用机制、降解微生物、降解基因、矿化途径、污染物的微生物修复及抗性转基因作物的研究进展,展望了2,4-滴降解基因在环境污染修复中的应用以及抗2,4-滴转基因作物作为草甘膦抗性作物补充的前景。     

2,4-滴丁酯除草剂的绿色合成

[目的]2,4-滴丁酯属于苯氧羧酸类除草剂,应用广泛且较少产生耐药性,研发2,4-滴丁酯的绿色合成具有重要意义。[方法]2,4-二氯苯氧乙酸与硼酸三丁酯在无溶剂、无催化剂条件下反应,经减压蒸馏分离得到2,4-滴丁酯。[结果]确定了合成2,4-滴丁酯的最佳反应条件:反应温度140℃,硼酸三丁酯与2,4-二氯苯氧乙酸的摩尔比为2∶1,反应时间4 h,在此条件下酯化率达93.7%。[结论]无溶剂无催化剂条件下合成2,4-滴丁酯,绿色环保,收率高,分离方便,具有工业化应用前景。     

磺化硅胶催化合成2,4-滴丁酯

以2,4-二氯苯氧乙酸和正丁醇为原料,磺化硅胶为催化剂,催化合成除草剂2,4-二氯苯氧乙酸正丁酯(2,4-滴丁酯)。考察催化剂用量、原料配比及回流时间对反应的影响。结果表明,最佳反应条件为:催化剂用量为2,4-二氯苯氧乙酸质量的1.4%,n(正丁醇):n(2,4-二氯苯氧乙酸)=10:1,回流时间为1.0 h,2,4-二氯苯氧乙酸正丁酯的收率为98.7%。     

两种测定水中2,4-滴分析方法的比较

本文分别采用气相色谱法和高效液相-质谱法对水中2,4-滴进行测定,对两种方法的校准曲线、检出限、准确度进行分析比较.结果表明两种方法曲线相关性、准确度良好,检出限均可满足日常监测需求;气相色谱法的检出限更低,在低浓度检测方面表现更佳,但需要衍生化反应,实验时间长;高效液相-质谱法可直接进样,无需衍生,但灵敏度不如气相色...     

三氟甲磺酸催化便捷高效合成2,4-滴丁酯除草剂

以2,4-二氯苯氧乙酸与正丁醇为原料,三氟甲磺酸为催化剂,催化合成2,4-滴丁酯,考察了醇酸摩尔比、反应时间及催化剂用量等对反应的影响。结果表明,合成2,4-滴丁酯的最佳反应条件是:正丁醇与2,4-二氯苯氧乙酸的摩尔比为3∶1,催化剂用量为0.2%(占2,4-二氯苯氧乙酸摩尔量),回流反应8 h,在此条件下,酯化率达97.1%。     

二氯甲烷萃取气相色谱法测定饮用水中的2,4-滴

采用二氯甲烷萃取-毛细管柱气相色谱电子捕获检测器(GC-ECD)测定饮用水中的2,4-滴.方法:水样中的2,4-滴在酸性条件下经二氯甲烷萃取,用碘甲烷酯化,生成较易挥发的甲基化衍生物,利用带电子捕获检测器的气相色谱仪进行检测.结果表明2,4-滴最低检测质量浓度为0.10μg/L.在0.1～50.0μg/L范围内线性关系...     

硅胶负载硅钨酸催化合成2,4-滴丁酯

以硅胶负载硅钨酸为催化剂(H4SiW12O40/SG),2,4-二氯苯氧乙酸和正丁醇为原料合成2,4-滴丁酯.探讨H4SiW12O40/SG对酯化反应的催化活性,较系统地研究了酸醇物质的量比、催化剂用量、反应时间等因素对产物收率的影响.实验表明:H4SiW12O40/SG是合成2,4-滴丁酯的良好催化剂,固定2,4-二...     

气相色谱法测定2,4-滴丁酯在水果中的残留

建立了气相色谱测定水果中2,4-滴丁酯残留量的简单快速的方法.水果样品经提取、净化、浓缩后,用带有ECD检测器的气相色谱仪检测2,4-滴丁酯的残留量.方法的最低检出限0.005 mg/kg,样品中2,4-滴丁酯平均添加回收率在74.60%～99.70%之间,变异系数在3.12%～7.76%之间.     

Adsorption of 2,4-Dichlorophenoxyacetic Acid and Phenoxyacetic Acid on Sibunit

The kinetics of adsorption of the typical herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and phenoxyacetic acid (the product of 2,4-D decay in the natural environment) on the activated carbon Sibunit was studied in an aqueous medium. The porosity and surface structure of the carbon were studied. The orders of 2,4-D and phenoxyacetic acid adsorption were determined. The high adsorption capacity of Sibunit for these substances was found.     

十六烷基三甲基溴化铵催化合成2,4-二氯苯氧乙酸

利用十六烷基三甲基溴化铵催化氯乙酸和2,4-二氯苯酚合成2,4-二氯苯氧乙酸,十六烷基三甲基溴化铵具有较高的催化活性,可以加快合成2,4-二氯苯氧乙酸.反应过程考察了2,4-二氯苯酚与氯乙酸摩尔比、催化剂用量、反应时间、反应温度对产率的影响以及催化剂的重复使用性能.反应的最佳条件为:在85℃下,2,4-二:氯苯酚和氯乙...     

2,4-二氯苯氧乙酸合成方法的正交试验研究

改进2,4-二氯苯氧乙酸(2,4-D)传统的合成工艺。主要反应不是采取先氯化的方法,而是先以苯酚和氯乙酸缩合后,再用次氯酸钠进行氯化的后氯化法,进而用正交试验,确定了新方法的最佳工艺条件:投料比为苯氧乙酸/g∶冰醋酸/mL=1∶9,次氯酸钠投入量为18mL(滴加),反应温度为冰水浴中进行,酸化至pH<1条件下,产品收率最高。测定了产品的mp IR和NMR,均与文献值相符。     

Molecularly Imprinted Polymers Based on Chitosan for 2,4-Dichlorophenoxyacetic Acid Removal

The development of low-cost and eco-friendly materials for the removal of pollutants from water is one of the main modern challenges. For this purpose, molecularly imprinted polymers were prepared under optimized conditions starting from chitosan (CS), chemically or ionically modified with glycidyl methacrylate (GMA) or itaconic acid (ITA), respectively. 2,4-Dichlorophenoxyacetic acid (2,4-D) was used as a template, obtaining the CS_GMA and CS_ITA series. The influence of the template concentration on the MIPs’ (molecularly imprinted polymers) morphology, thermal behaviour and swelling ability, as well as on the 2,4-D removal capacity, were analyzed. The amount of the template used for the imprinting, together with the different permeability of the matrices, were the key factors driving the analyte uptake process. Despite the good performance shown by the non-imprinted CS_GMA sample, the best results were obtained when CS_GMA was imprinted with the highest amount (5%) of template (CS_GMA_5). This system was also more efficient when consecutive adsorption experiments were carried out. In addition, CS_GMA_5 had a desorption efficiency of 90–100% when a low pesticide concentration was used. These findings suggest that the presence of imprinted cavities could be useful in improving the performance of sorbent materials making CS_GMA_5 a possible candidate for 2,4-D removal.     

The Effects Of Humic Substances On Pinus Callus Are Reversed By 2,4-Dichlorophenoxyacetic Acid

The reversal of humic matter-induced inhibition of callus growth and metabolism by 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in Pinus laricio. Two forest humic fractions (relative molecular mass (M_r) > 3500), derived from soil under Fagus sylvatica (Fs) and Abies alba (Aa) plantation, were used. Pinus laricio callus was grown for a subculture period (4 weeks) on Basal Murashige and Skoog (MS) medium plus forest humic matters (Fs or Aa), at a concentration of 1 mg C/l, and then was transferred, for an additional four weeks, to a MS medium culture without humic matter, but with different hormones: indole-3-acetic acid (IAA, 2 mg/1) or 2,4-dichlorophenoxyacetic acid (2,4-D, 0.5 mg/1) and/or 6-benzylaminopurine (BAP, 0.25 mg/1). Growth of calluse, glucose, fructose, and sucrose contents, and activities of soluble and bound invertases, glucokinase, phosphoglucose isomerase, aldolase, and pyruvate kinase were monitored. The results show a negative effect of humic fractions on callus growth, due to decreased utilization of glucose and fructose, and decreased activities of glycolytic enzymes. The effects are reversible. Substitution of humic fractions with 2,4-D+BAP or 2,4-D is followed by an increase of glycolytic enzyme activities and, consequently, by the utilization of glucose and fructose that induces a restart of growth. In contrast, the inhibitory effects of humic fractions persist when they are substituted with BAP alone, indicating that only the auxin 2,4-D is capable of reversing the negative effects. A possible competitive action on the auxin-binding site between 2,4-D and the chemical structures in the forest humic fractions is suggested.     

A study of adsorption behavior of 2,4-Dichlorophenoxyacetic Acid onto various GACs

Adsorption and desorption of 2,4-dichlorophenoxyacetic acid (2,4-D) onto granular activated carbon (GAC) were studied to get basic information on their removal from aqueous solution. Single species adsorption equilibria of 2,4-D dissolved in water have been measured using F400, SLS103, and WWL. Equilibrium capacity increased with decreasing pH. The magnitude of adsorption capacity of 2,4-D was the order of F400> SLS103>WWL. Kinetic parameters were measured in a batch adsorber to analyze the adsorption rate of 2,4-D. The internal diffusion coefficients were determined by comparing the experimental concentration curve with that predicted from the surface diffusion model (SDM) and Pore diffusion model (PDM). The linear driving force approximation (LDFA) model was used to simulate isothermal adsorption behaviors in a fixed bed adsorber and successfully simulated experimental adsorption breakthrough behavior under various operation conditions. This paper is dedicated to Professor Dong Sup Doh on the occasion of his retirement from Korea University.     

Photocatalyzed Degradation of Phenol, 2,4-Dichlorophenol,Phenoxyacetic Acid and 2,4-Dichlorophenoxyacetic Acid over SupportedTiO2 in a Flow System

The photodegradation of phenol, 2,4-dichlorophenol, phenoxyacetic acid and 2,4-dichlorophenoxyacetic acid using TiO₂ as photocatalyst is investigated. The photodegradations of these compounds have been conducted in a continuous mode by means of a flow system, in which TiO₂ remains fixed onto glass pearls. The use of this system gives high yields of degradation for the chemicals tested, except for 2,4-dichlorophenol for which a slow dechlorination process is observed. The rate of photodegradation depends on the pH of the solution, the point of zero charge of TiO₂ and the pK_a of the chemicals being the key parameters. The main aromatic intermediates detected have been hydroquinone,paraquinone and hydrohydroquinone during phenol degradation; phenol and hydroquinone during phenoxyacetic acid degradation; chlorohydroquinone and chlorophenol during 2,4-dichlorophenol degradation; and dichlorophenol during 2,4-dichlorophenoxyacetic acid degradation. Finally, some long term irradiations with phenol as model compound have been performed, showing high degrees of photodegradation. It has been observed that only a periodic evacuation of the effluent out of the reactor is needed to sustain high percentages of photodegradation.     

2,4-二氯苯氧基乙酸从腐植酸、金属氧化物、腐植酸金属络合物上解吸附作用的动力学研究

农药残留已经成为环境污染的一大重要来源。通过2,4-D从金属氧化物,腐植酸金属络合物以及腐植酸表面上解吸附的动力学分析与对比,考察腐植酸在农药中的作用。     

2,4-二羟基二苯甲酮生产废水处理的研究

采用Fenton法 微波预处理紫外线吸收剂2,4-二羟基二苯甲酮生产废水,在pH为3.20时,Fenton法预处理最佳H2O2/Fe2 摩尔比为13.2:1.在最佳摩尔比条件下,当H2O2:的用量为1 mL、反应时间为90 min时,CODcr去除率为21.9%.引入微波辐照处理后,在活性炭量3 g,微波功率800 W下辐照90 s,经絮凝沉淀,CODcr的去除率为23.8%,再经厌氧 生物接触氧化处理,出水CODcr300 mg/L.