N-(2,5-二氯苯基)-6-氯-2-(4,6-二甲氧基-2-嘧啶氧基)胺的合成及除草活性

以2,5-二氯苯胺、6-氯水杨醛和4,6-二甲氧基-2-甲砜基嘧啶为原料,设计并合成了2-嘧啶氧基-N-芳基苄胺类化合物N-(2,5-二氯苯基)-6-氯-2-(4,6-二甲氧基-2-嘧啶氧基)苄胺,其化学结构经核磁共振氢谱和质谱分析确证。室内生物测定结果显示,该化合物对单子叶杂草稗草、马唐、狗尾草以及双子叶杂草反枝苋、芥菜具有较好的芽后除草活性,在有效剂量75 g/hm2下其抑制率达到80% ~100%;对棉花安全,在有效剂量225 g/hm2下未产生明显药害,在棉花和棉田杂草反枝苋之间的选择性系数为24.93。初步表明该化合物在棉田具有一定开发应用价值。     

Determination of N-(3-ethylsulfonyl-2-pyridinyl)-4,6-dimethoxy-2-pyridineamine in soil after treatment with rimsulfuron

An analytical procedure to detect N-(3-ethylsulfonyl-2-pyridinyl)-4,6-dimethoxy-2-pyridineamine, a degradation product deriving from the hydrolysis of rimsulfuron in soil, has been developed. The analytical standard was prepared by basic hydrolysis of rimsulfuron at pH 9 and purification on a silica gel chromatographic column. The compound obtained was stable at high temperature, thus enabling determination by gas chromatographic analysis. Soil samples were extracted with acetonitrile, purified with a SPE C18 cartridge and analysed using both nitrogen phosphorus (NPD) and mass spectrometer detectors. The analytical procedure described proved to be sensitive and reproducible. Recoveries varied from 84 to 90%. The limit of sensitivity was 0·001 mg kg^-1. © 1997 SCI.     

Technique for measuring the relative movement of herbicides in soil under leaching conditions

A technique for determining the relative leaching of herbicdes in soil is described. This consists of coating a glass plate with a uniformly thin layer of soil, applying the herbicde as a streak to the bottom of the plate and then cluting it with water. This is analogous to thin-layer chromatography. After clution, the position of the herbicide is determined by a bioassay with browntop grass (Agrostis tenuis). This provides a speedy and economical method which is particularly useful as a screen for experimental herbicides.     

Base-catalysed hydrolysis of (E)- and (Z)-mevinphos

The rates at which (E)- and (Z)-mevinphos are hydrolysed in aqueous solutions in the pH range 8.7–11.5, and in the temperature range 30–50°C, have been measured. The overall activation parameters have been calculated, and equations to allow calculation of the rates in any basic conditions are given. The complicated routes by which (E)- and (Z)-mevinphos are hydrolysed to simple molecules have been deduced. The rates for the individual steps in each route have been either measured experimentally, or have been calculated through analogue simulation of all the reactions, by matching the calculated to the observed ultraviolet spectral changes during hydrolysis. It is proposed that (Z)-2-carboxyl-1-methylvinyl dimethyl phosphate is not observed as a hydrolysis product of (Z)-mevinphos because it decomposes by an extremely fast intramolecular reaction. The reasons for the greater lability of (E)-mevinphos are also discussed.     

1-苯基(甲基)-3-甲基-5-(4,6-二甲基-2-嘧啶基硫基)-4-吡唑甲醛肟醚(酯)类化合物的合成及生物活性

合成了未见文献报道的含硫醚键的吡唑肟醚（酯）类化合物18个，所有新化合物的结构经元 素分析、1H NMR、IR和MS确认。部分化合物经生物活性初筛表现出抗菌活性与除草活性。     

The influence of herbicides on the viability of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae)

Entomopathogenic nematodes (EPNs) are agents that can be used for the biological control of pests associated with pesticides in a tank mix. Compatibility studies need to be conducted to analyse which products are compatible with EPNs. The survival of infective juveniles (IJs) of four species of EPNs (Steinernema, Heterorhabditis) was determined after exposure to eight chemical herbicides. The effect of direct IJs exposure to herbicides for 1, 4 and 24 h was tested in a Petri dish at 15, 20 and 25 °C. The study showed that Steinernema kraussei was the most tolerant among the tested EPN species, while S. carpocapsae was the most sensitive to all tested herbicides. The lowest mortality of IJs was at 15 °C (19%). Our investigation showed, overall, the herbicides negatively affected EPN survival. The results confirmed that the compatibility is a species-specific characteristic, influenced by the temperature and time of exposure. Application of two different control ingredients (insecticide and herbicide) at the same time would reduce cost and time consumption in pest/weed control.     

Degradation and adsorption of carbendazim and 2-aminobenzimidazole in soil

Increasing adsorption of [¹⁴C]-labelled carbendazim in soil took place within a few weeks of incubation and was greatest in soil with a high organic matter content. Carbendazim was slowly decomposed in soil, mainly by soil microorganisms. After 250 days of incubation in two unsterilised soils, 13 and 5% respectively of added [¹⁴C]-carbendazim was recovered compared with 70 and 50% respectively from sterile soils; 4–8% of added carbendazim was recovered as 2-aminobenzimidazole (2-AB) from both unsterilised and sterile soil. After 270 days' incubation, 33 and 9% of ¹⁴C was recovered as ¹⁴CO₂ from soil supplied with [¹⁴C]-carbendazim (20 and 100 mg/kg) respectively. Degradation started more rapidly when carbendazim was added to soil preincubated with the fungicide but the degradation rate was very low in all cases, indicating that the compound is a poor microbial energy source and that the degradation is a co-metabolic process. 2-AB was found as a degradation product although it appeared to be unstable in soil, decomposing rapidly after a lag period of about 3 weeks; small amounts remained in the soil for several months, however, presumably adsorbed on soil particles.     

Degradation of the insecticide SD 8280, 2-chloro-1-(2, 4-dichlorophenyl)vinyl dimethyl phosphate,in soils

The degradation of the insecticide SD 8280 [2-chloro-1-(2,4-dichlorophenyl)vinyl dimethyl phosphate] in soil has been examined under laboratory conditions using two soils from rice-growing areas in Japan and one UK soil. In all soils SD 8280 underwent degradation to 1-(2,4-dichlorophenyl)ethanol, 2,4-dichlorobenzoic acid, 2-chloro-1-(2,4-dichlorophenyl)vinyl methyl hydrogen phosphate and 2′,4′-dichloro-acetophenone. These degradation products were present in the soils as free (extractable) compounds and as bound forms and soil binding occurred most extensively with 2,4-dichlorobenzoic acid. Polar products were also formed and these appeared to be in part the result of complexing of degradation products with the soil organic matter. The effect on the degradation of the insecticide of varying the moisture content of one soil was also examined. In soil incubated at 11, 17, 30 and 62% moisture the recovery of SD 8280 after 60 days was 71.0, 12.3, 9.0 and 11.3%, respectively. Although the rate of degradation varied, the same degradation products were detected in all samples.     

Enantioselective transformation of the herbicides diclofop-methyl and fenoxaprop-ethyl in soil

The separate enantiomers of diclofop-methyl and fenoxaprop-ethyl were incubated with two soils under aerobic conditions. Rapid hydrolysis to the corresponding acids diclofop and fenoxaprop was observed. At various time intervals after soil treatment the parent compound and its free acid were extracted and the extracts were investigated by high-performance liquid chromatography. The determination of the K:S-ratio using a chiral stationary phase revealed that no racemisation of the esters took place. However, inversion of the hydrolysis products was observed. In both soils the acids with the S-configuration showed a significantly higher inversion tendency than the acids with the R-configuration. In one soil the S-acids of both herbicides were inverted (50% inversion in 4–7 days) to yield, ultimately, a residue containing 70% R- and 30% S-enantiomer.     

The effect of repeated applications of 2,4-D and MCPA on their breakdown in soil

The effect of repeated applications of 2,4-D and MCPA in a long-term field experiment on their subsequent degradation was investigated. The herbicides had been applied annually since 1954, Comparisons were made with plots treated once and then retreated the following year. Repealed applications of the two herbicides resulted in a reduction in degradation lime from 10 weeks for 2,4-D and 20 weeks for MCPA after one application to 4 and 7 weeks respectively after 19 years of annual application. In spite of an increased capability of the soil microflora lo degrade 2,4-D and MCPA 9 months after a previous treatment. no change in numbers of organisms capable of utilizing the substances as carbon sources were found in treated plots as compared with the control. It is obvious that there is a cross adaptation between 2,4-D and MCPA. It seems most likely that two different ‘enrichment’ been induced, each capable of decomposing both herbicides, but with different efficiencies. Effet d'applications répétée de 2,4-D et de MCPA sur leur degradation dans le sol L'effet d'applications répétée de 2.4-D et de MCPA sur leur degradation uléerieure a étéétudié dans une expérience au champ de longue durée. Les herbicides ont été appliqués chaque année depuis 1954. Des comparaisons ont été effectuées avec des parcelles traiées une fois et traitées à nouveau l'année suivante. Les applications répétées des deux herbicides ont provoqué une réduction du temps de dégradation qui est passé de 10 semaines pour le 2,4-D et 20 semaines pour le MCPA après une seule application, à 4 et 7 semaines respectivement, après 19 années d'applications annuelles. En dépit d'une capacité accrue de la microflore du sol à dégrader le 2.4-D et le MCPA, neuf mois après un traitement préalable, aucun changement n'a été constaté dans le nombre des organismes capables d'utiliser les produits comme sources de carbone dans les parcelles traitées, par rapport au témoin. II est évident qu'il y a une adaptation croisée entre le 2,4-D et le MCPA. II apparait très probable que deux ‘enrichissements’ de Hores ont été induits, chacun d'eux étant capable de décomposer les deux herbicides mais avec des efficacités différentes. Die Wirkung wiederholter Behandlungen von 2.4- D und MCPA auf ihren Abbau im Boden Die Wirkung wiederholter Anwendungen von 2,4-D und MCPA auf ihren Abbau wurden in einem Freiland-Versuch untersucht. Die Herbizide wurden jährlich, sell 1954 ange-wendet. Es wurden Vergleiche mil Parzellen angcstellt, die zum erstenmal und im folgenden Jahr nochrnaK bchandelt worden waren. Die widerholien Behandlungen mit den beiden Herbiziden bewirkte elne Verringerung der Ab-bauzeit von 10 Wochen fur 2,4-D und 20 Wochen fiir MCPA nach einer Behandlung, auf 4 bzw. 7 Wochen nach 19 Jahren jahrlicher Anwendung. Trotz der erhohten Ffihigkeit der Bodenmikroflora 2,4-D und MCPA neun Monate nach einer vorhergehenden Behandlung abzubauen, war die Zahl der Organismen, die diese Herbizide als Kohlensloffquelle verwerten konnen, in den behandelten und unbehandelten Parzellen gleich gross. Zwischen 2.4-D und MCPA existiert ofVensichtlich elne Kreuz-Adaplalion. Sehr wahrscheinlich wurden zwei versehiedene ‘enrichment’-Floren induziert, von der jede in der Lage ist beide Herbizide, aber mit unterschiedlicher Effizienz, Hbzubauen.     

Hydrolysis of cyanazine and related diaminochloro-1,3,5- triazines. Part II: hydrolysis in sulphuric acid solutions

Hydrolysis of cyanazine in sulphuric acid solutions involves primary attack at the nitrile group to give first the corresponding amide and then the carboxylic acid followed subsequently by displacement of the chlorine atom. Comparison of the respective reaction rates showed that, in sulphuric acid solutions (at concentrations around 0.5_M) at 25°C, the rate of this attack at the nitrile group is approximately ten times faster than at the chlorine atom. The kinetic data indicate that in these moderately acid solutions the mechanism of cyanazine hydrolysis corresponds to an A-2 reaction involving prior protonation of the nitrile group followed by rate determining nucleophilic attack by water. However, at higher acidities, the rates decelerate which leads both to diversion from the Zucker-Hammett postulate for simple A-2 reactions and to undue curvature in the Bunnett or Bunnett-Olsen linear free-energy plots, so that with the present data such a conclusion cannot be extended to the reaction in solutions of acidity higher than 0.5_M. Removal of the chlorine atom attached to the 1,3,5-triazine ring in atrazine was also found to be an A-2 reaction in moderately acid solutions, but at higher acidities ([H⁺]>2_M), there is an acceleration in the rate. It is suggested that this is a consequence of diprotonation of the diamino-1,3,5-triazine molecule.     

N-[2-(4,6-二甲氧基嘧啶-2-氧基)苯亚甲基]取代胺类衍生物的合成及除草活性

以水杨醛为原料,经取代、加成和消除反应合成了6个标题化合物(3a~3f),其中4个(3a~3d)为新化合物,其结构经核磁共振氢谱、质谱和元素分析确认。初步的除草活性测试结果表明,在有效成分150 g/hm2的剂量下,除化合物3f对稗草Echinochloa crus-galli的抑制率为55%外,其余5个化合物对供试杂草的抑制率均在80%以上,部分化合物对稗草、早熟禾Poa annua、反枝苋Amaranthus retroflexus或小藜Chenopodium album的抑制率达100%。     

新型N-芳基-2-((5-((4,6-二甲基嘧啶-2-基)硫甲基)-1,3,4-噻二唑-2-基)硫)乙酰胺类化合物的合成及杀菌活性

为寻找新型杂环活性化合物,通过活性亚结构拼接,以硫脲和乙酰丙酮为起始原料合成4,6-二甲基嘧啶-2-硫醇,随后经酯化、肼化、环化和缩合反应,设计并采用微波辅助合成了10个新型N-芳基-2-（（5-（（4,6-二甲基嘧啶-2-基）硫甲基）-1,3,4-噻二唑-2-基）硫）乙酰胺类化合物,其结构通过核磁共振氢谱和碳谱、红外光谱、质谱及元素分析确认。初步生物活性测试结果表明,在50 mg/L下,大部分目标化合物对植物病原真菌具有一定的抑制活性,其中化合物8h对黄瓜炭疽病菌Colletotrichum orbiculare的抑制率达77.3%。     

Synthesis and plant growth regulating properties of derivatives of alkyl 3-benzoyl-3-(3-chloro-4-substituted phenyl)-2-methylcarbazates

Alkyl 3-benzoyl-3-(3-chloro-4-substituted-phenyl)-2-methylcarbazates (isoelectronic analogues of wild oat herbicides) have plant growth regulating properties for various weeds and crops. Some derivatives of carbazates, bearing halogen in the 4-position of the phenyl group, have been shown to have the highest activity of the prepared compounds.     

The degradation of (Z)- and (E)-1,3-dichloropropenes and 1,2-dichloropropane in soil

The degradation in soil of the major constituents of a 1,3-dichloropropene-1,2-dich-loropropane nematicide has been studied under laboratory and outdoor conditions. In sealed glass containers, ( Z)- and ( E)-1,3-dichloropene- 2-¹⁴C were converted in soil into the corresponding 3-chloroallyl alcohols and these alcohols were in part strongly bound to the soil. The ( Z)- and ( E)-3-chloroacrylic acids were also found as minor products. More polar products were detected and these released the chloroacrylic acids in 20–30% yield upon hydrolysis. Although the 1,3-dichloropropenes were lost by volatilisation from soil stored in open glass jars outdoors, they also underwent degradation to the same products that were detected in sealed containers. There was evidence of only slight degradation of 1,2-dichloropropane- 2-¹⁴C (4 % or less of the applied radioactivity remained unextracted from a loam soil after 5 months). When soil treated with the 1,2-dichloropropane was stored outdoors in an open glass container, less than 1 % of the original radiolabel remained in the soil after 10 days under these conditions due to volatilisation of the applied material. In a separate experiment potatoes were grown in soil 6 months after treatment with a mixture of both ( Z)- and ( E)-1,3-dichloropropene- 2-¹⁴C and 1,2-dichloropropane- 2-¹⁴C. Although 5 % of the applied radiolabel remained in the soil at potato harvest the potato tubers contained only a very small residue (0.007 mg/kg).     

N-苯基-2-(4,6-二甲氧基-2-嘧啶氧基)-6-氯-苄胺(ZJ1835)的除草活性研究

为明确新化合物N-苯基-2-(4,6-二甲氧基-2-嘧啶氧基)-6-氯-苄胺(ZJ1835)在棉花田的应用前景,就其对棉花的安全性、选择性、杀草谱和田间应用技术进行了研究。室内生物测定结果表明,ZJ1835对棉花生长初期有一定矮化作用,但不影响出苗和后期生长,在有效剂量225 g/hm2下对棉花安全性好;对不同棉花品种之间的安全性有一定差异,其中对王岳9913的安全性最好,其次为银山1号和福棉6号,对冀丰197安全性略差;该化合物在棉花与马唐、反枝苋之间的选择性系数分别为2.14和13.00,具有较好的选择性;多数田间常见杂草对其敏感,杀草谱较广。田间试验结果显示,ZJ1835在90～120 g/hm2有效剂量下对供试棉花安全性好,对棉田杂草总防效为82.1%～92.8%,具有一定的开发应用潜力。     

Dissipation of 4-chloro-2-methylphenoxyacetic acid (MCPA) in a rice field

The dissipation of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) in a California rice field was investigated. Samples of water, rice plants and mud were collected at intervals for 20 days and analysed for MCPA by established methods for plants and mud, and by a novel method utilising XAD-2 macro-reticular resin for water. Water residues declined to less than 0.01 parts/10⁶ of MCPA within 14 days after application; plant residues declined from 20 parts/10⁶ to 1 part/10⁶ within 20 days; mud residues remained constant at about 0.1 parts/10⁶. Photolysis of dilute aqueous MCPA solutions with either sunlight or an indoor photoreactor yielded 4-chloro-2-methylphenol as the major product; o-cresol and 4-chloro-2-formylphenol also were identified. While photosensitisation was observed with water taken from the rice field, microbial degradation proceeded at an even faster rate. All environmental compartments except air contained measurable amounts (>0.01 parts/10⁶) at some time, but water contained the bulk of the applied MCPA whose eventual disappearance was shown to be due to biological and chemical degradation and not dilution.     

Different in-planta and ex-planta activities of 7-chloro-4-(2-[trifluoromethyl]phenoxy)quinoline against Pyricularia grisea due to volatilization

7-Chloro-4-[2-(trifluoromethyl)phenoxy]quinoline (L Y248908) strongly inhibits mycelial growth of Pyricularia grisea in ex-planta assays but, when applied to the foliage of rice seedlings, its protective and curative properties against P. grisea are poor. The principal cause for this difference was found to be volatilization of LY248908 from treated foliage. Variations in fungal sensitivity (due to strain or development stage) and compound loss due to translocation, sequestration, metabolism, or degradation were shown not to be significant.     

Factors favouring the choice of flamprop-methyl,methyl (±)-2-[N-(3-chloro-4-fluorophenyl)benzamido] propionate for the control of avena species in wheat

The post-emergence herbicide, methyl (±)-2-[N-(3-chloro-4-fluorophenyl)benzamido]-propionate, flamprop-methyl, showed good activity against oat with selectivity in wheat. It was superior in performance to flamprop-isopropyl and benzoylprop-ethyl already being marketed for wild oat control. It gave even more effective control of seed set in the oat than did the other compounds, prevented tiller growth and as a result of its higher activity was less dependent on crop competition. Selectivity of flamprop-methyl, however, was similar to that previously reported for related compounds, i.e. it was dependent on its rate of degradation and the subsequent detoxication of the biologically active acid to inactive conjugates. The rate of degradation of flamprop-methyl is comparable to that of benzoylprop-ethyl but the more active acid produced accounts for the improved performance of the former. The corresponding ethyl ester showed the highest rate of degradation and although generally comparable in performance to the methyl ester there was a tendency for the inhibition on the oat to last for a shorter period. Performance of flamprop-methyl is influenced by environmental factors such as temperature or water stress. These factors had an effect during the first 2 weeks after compound application, reducing the translocation of the active metabolite to its site of action and having a small but detectable effect on the amount of acid produced.