N-桥连芳基吡咯类衍生物的合成、晶体结构及杀虫杀螨活性研究

以1-溴甲基-2-(4-氯苯基)-3-氰基-4-溴-5-三氟甲基吡咯为起始原料合成了3个新颖的N-桥连芳基吡咯类衍生物5a～5c. 通过氢谱、红外、元素分析及X射线单晶衍射确证了结构. 发现当2-(4-氯苯基)-3-氰基-4-溴-5-三氟甲基吡咯分别与S2Cl2, SCl2, 次磺酰氯, 亚磺酰氯反应时, 均未得到预期的N桥连产物, 却得到了Br被S取代的非预期产物. 杀虫杀螨活性结果显示目标产物5a～5c对东方粘虫、尖音库蚊幼虫、朱砂叶螨具有选择性, 如5a对东方粘虫具有很好的杀虫活性, 5a和5b在0.5 mg•g－1浓度下对尖音库蚊的杀虫活性为100%, 5b对朱砂叶螨具有很好的杀螨活性, 达到了商品化品种溴虫氰的水平.     

气相色谱-串联质谱法测定台湾青枣中的炔螨特、戊唑醇和溴螨酯残留

建立了台湾青枣（Zizyphus mauritiana Lam）中炔螨特、戊唑醇和溴螨酯同时测定的气相色谱-串联质谱（GC-MS/MS）分析方法。样品用乙腈匀浆提取,盐析,石墨化炭黑/氨基混合型固相萃取柱净化,乙腈/甲苯（3：1,v/v）洗脱,浓缩定容后检测。目标化合物经SLB-5MS色谱柱（30 m×0.25 mm×0.25 μm）分离,采用三重串联四极杆质谱多反应监测（MRM）模式进行定性定量分析。结果表明,在0.01~0.50 mg/kg添加水平时,3种农药的回收率为75.8%~103.6%,相对标准偏差为1.7%~9.3%（n=5）。方法的线性范围为0.01~0.50 mg/kg,决定系数（R²）>0.99。该方法对炔螨特、戊唑醇和溴螨酯的定量限均为0.01 mg/kg,能满足台湾青枣中炔螨特、戊唑醇和溴螨酯残留检测的要求。     

QuEChERS净化GC/ECD测定苹果和柑橘中4种常用杀螨剂残留

采用QuEChERS方法净化,建立了气相色谱法/电子捕获检测器(GC/ECD)同时检测苹果和柑橘中四螨嗪、虫螨腈、溴螨酯和哒螨灵残留的分析方法。苹果和柑橘样品用乙腈提取,适量C_(18)填料和无水MgSO_4净化提取液,GC/ECD检测,基质匹配标准溶液外标法定量。四螨嗪、哒螨灵在0.02~2.0 mg/L浓度范围内,虫螨腈、溴螨酯在0.004~0.5 mg/L浓度范围内的线性关系良好,相关系数(r)均大于0.99,定量下限(LOQs)为0.001~0.02 mg/kg。苹果和柑橘样品中4种杀螨剂的平均加标回收率(n=6)为76.4%~111.8%,相对标准偏差(RSDs)不超过13.4%。该方法简便、快速,能够满足苹果和柑橘中上述4种杀螨剂残留同时检测的需要。采用该方法测定了4种杀螨剂在苹果和柑橘中的残留量,结果满意。     

超高压液相色谱法测定水果和蔬菜中虫螨腈及其代谢物以及在甘蓝中的残留评价应用

建立了采用固相萃取柱净化,超高压液相色谱（UPLC）同时测定蔬菜和水果中虫螨腈及其代谢物溴代吡咯腈残留量的分析方法。方法验证结果表明,在25～5 000 ng·mL－1范围内目标化合物的质量浓度和仪器响应呈良好线性关系,相关系数（r2）为0.997～1.000;在0.05、1、2 mg·kg－1加标水平下,目标化合物的回收率为84.6%～111%,相对标准偏差为1.6%～14%;方法定量下限均为0.05 mg·kg－1。2020年在全国12地开展田间试验,360 g·L－1虫螨腈悬浮剂以20 mL/亩（125.28 g a.i./ha）施药1次,甘蓝中虫螨腈的消解动态符合一级动力学方程,半衰期为4.1～11.0 d。当采样间隔为末次施药后14 d和21 d时,虫螨腈在甘蓝中的残留量分别为小于0.05～0.488 mg·kg－1和小于0.05～0.370 mg·kg－1,溴代吡咯腈的残留量均低于0.05 mg·kg－1。结合我国制定的虫螨腈在甘蓝上的最大残留限量,推荐采收安全间隔期为14 d。膳食风险评估结果表明：普通人群虫螨腈（膳食风险评估定义）的国家估算每日摄入量为1.28 mg,占日允许摄入量的67.7%,对一般人群健康均不会产生不可接受的风险。     

气相色谱-负化学电离质谱法(GC-NCI MS)对虫螨腈在茄子和土壤中残留的分析

虫螨腈(chlorfenapyr),又名溴虫睛;化学名称:4-溴-2-(4-氯苯基)-1-乙氧基甲基-5-三氟甲基吡咯-3-腈;CAS登记号:122453-73-0;分子式:C15H11BrClF3N2O;相对分子质量:407.62;结构式如图1,是由美国氰胺公司开发的一种新型的杀虫、杀螨剂,其作用机理新颖,杀虫谱广、对常规农药无交互抗性,并对人、鸟、鱼、蚕低毒[1].     

环丙烷甲酸-2-萘甲酯(杀螨剂)的合成

采用一种新的方法合成了环丙烷甲酸-2-萘甲酯。这种杀螨剂的合成过程为, 在碱、季胺型TOMAC相转移催化作用下, 1,2-二溴乙烷与丙二酸二乙酯反应合成1,1-环丙烷二羧酸, 然后脱羧, 得到环丙烷甲酸, 再制成环丙烷甲酸钠, 在Bu~4NBr(TBAB)季胺型相转移催化作用下, 与2-(溴甲基)萘合成得环丙烷甲酸-2-萘甲酯。其总产率为12.9％, 纯度为95.5％。初步证明对螨类害虫─柑桔红蜘蛛有效。     

间叔丁基苯乙醚的合成研究

通过两条路线合成了生产新型农药乙螨唑的关键中间体间叔丁基苯乙醚。其一以叔丁基苯为原料,通过溴代、硝化、还原(脱卤素)、重氮化和乙醚化反应得到目标化合物;另一采用对氨基叔丁基苯为原料,通过乙酰化、溴代、脱乙酰化、重氮化去氨基和乙醚化反应得到目标化合物。两条路线的总收率都较高,分别为45%和63%。所得产品中未检测到异构体对叔丁基苯乙醚,质量好,纯度高。其中路线一原料便宜,操作简单,更适合进一步工业化放大生产。合成路线中的有机中间体和目标化合物的化学结构通过MS和NMR进行确证。     

新型4,4-二甲基异噁唑-3-酮衍生物的合成及生物活性研究

以Baylis-Hillman加成物为起始原料,设计并合成了5个结构新颖的4,4-二甲基异唑-3-酮衍生物。所合成的化合物经IR、1HNMR和元素分析确证。生物活性测试结果表明,所合成的目标产物在2000gai/ha的剂量下均具有较好的除草活性。中间体1-(2,4-二氯苯基)-2-溴甲基丙烯酸乙酯具有杀虫活性,在600gai/ha的剂量下对朱砂叶螨防效为100%。     

分散液液微萃取/液相色谱串联质谱法快速测定蜂蜜中10种杀螨剂

采用超声辅助-分散液液微萃取技术,建立快速测定蜂蜜中10种杀螨剂(四螨嗪,喹螨醚,吡螨胺,噻螨酮,乙螨唑,蝇毒磷,哒螨灵,克螨特,螺螨酯,唑螨酯)残留的液相色谱-串联质谱分析方法。电喷雾正离子扫描模式检测10种杀螨剂,基质匹配曲线定量。10种杀螨剂在0.10~100μg/L范围内线性良好,四螨嗪、喹螨醚、噻螨酮、乙螨唑、螺螨酯的定量限(S/N=10)为3.0μg/kg;蝇毒磷、哒螨灵、克螨特的定量限为1.5μg/kg;吡螨胺的定量限为2.0μg/kg;唑螨酯的定量限为2.5μg/kg。10种杀螨剂在10,50,100μg/kg加标浓度下,回收率在72%~107%之间,相对标准偏差RSD12%。     

烷烃的自由基溴化

作者用N-溴代二乙胺和典型溴化剂N-溴代丁二酰亚胺分别对正戊烷、正己烧、正庚烷进行了光溴化,并与元素溴对烷烃直接光溴化进行了比较。 工作中找到了分离烷基溴化物的气相色谱条件,从而确定了元素溴对三种烷烃光溴化产物异构体的分布,并发现上述两种溴化剂光溴化产物的异构体分布与元素溴直接溴化结果基本相同。     

基于三维荧光光谱的乳制品脂氧化判别方法

为快速、无损判别乳制品脂氧化程度,提出了利用乳制品三维荧光光谱的氧化水平进行判别的方法。该方法用平行因子分析对荧光矩阵进行分解,用载荷向量组确定脂氧化过程中的光敏成分,用不同成分得分向量对样本进行聚类,并建立了不同氧化水平样本的偏最小二乘判别模型。实验采集不同存储环境下氧化程度各异的酸奶样本,找出了核黄素等荧光团在脂氧化过程中的变化规律,选取得分向量建立偏最小二乘判别模型对不同存储阶段氧化程度各异的样本判别分类,其特异度和灵敏度达88.9%以上,验证了该法对评判乳制品脂氧化水平的有效性。     

One-pot synthesis of tryptanthrin by the Dakin oxidation of indole-3-carbaldehyde

A one-pot approach to indolo[2,1-b]quinazolines from indole-3-carbaldehydes through the Dakin oxidation was developed. It was shown that the reaction proceeded through the condensation of indole-3-carbaldehydes with isatoic anhydrides, derived in situ from indole-3-carbaldehydes by the Dakin oxidation, and further oxidation/cyclization steps.     

Reversible crosslinking in cellulose. III. Factors controlling the oxidation behavior of mercapto groups in cotton derivatives

The oxidation behavior of mercaptocellulose prepared from tosylated cotton and of cellulose β-mercaptoethylaminocarboxylate (RDTC), which was prepared by reduction of a cotton derivative made by the reaction with bis-β-isocyanatoethyl disulfide, was studied, and the factors controlling the oxidation behaviors of solid polymeric mercaptans were discussed. RDTC was converted quantitatively to the corresponding disulfide by oxidation under mild conditions. Repeated oxidation–reduction cycles were applied to RDTC to demonstrate complete reversibility of disulfide crosslinking. On the other hand, only a portion of the mercaptan in mercaptocellulose could form disulfide by oxidation. It is considered that the mobility of the mercapto groups necessary for the oxidation coupling is restricted because they are attached directly to rigid cellulose chains. The oxidation of RDTC with air in alkaline medium was studied kinetically. It was found that the oxidation of the mercaptan in paired placement in the cellulose matrix proceeded more than ten times faster than that of the randomly placed mercaptan.     

Selective oxidation on metallic carbon nanotubes by halogen oxoanions

Chlorine oxoanions with the chlorine atom at different oxidation states were introduced in an attempt to systematically tailor the electronic structures of single-walled carbon nanotubes (SWCNTs). The degree of selective oxidation was controlled systematically by the different oxidation state of the chlorine oxoanion. Selective suppression of the metallic SWCNTs with a minimal effect on the semiconducting SWCNTs was observed at a high oxidation state. The adsorption behavior and charge transfer at a low oxidation state were in contrast to that observed at a high oxidation state. Density functional calculations demonstrated the chemisorption of chloro oxoanions at the low oxidation state and their physisorption at high oxidation states. These results concurred with the experimental observations from X-ray photoelectron spectroscopy. The sheet resistance of the SWCNT film decreased significantly at high oxidation states, which was explained in terms of a p-doping phenomenon that is controlled by the oxidation state.     

Identification of oxidation products and free radicals of tryptophan by mass spectrometry

New oxidation products and free radicals derived from tryptophan (Trp) oxidation under Fenton reaction conditions were identified using mass spectrometry. After the oxidation of tryptophan using hydrogen peroxide and iron (II) system (Fenton reaction), mono- and dihydoxy tryptophans and N-formylkynurenine were identified using electrospray mass spectrometry (ES-MS) and ES-MS/MS. Besides these products, new products resulting from the reaction of tryptophan and oxidized tryptophan and 3-methyl indole derivatives were also identified. The 3-methyl indole derivatives resulted, most probably, from the oxidation process and not from in-source processes. A dimer formed by cross-linking between two Trp radicals (Trp-Trp), similar to the previously described tyrosine dimer was observed, as well as the corresponding monohydroxy-dimer (Trp-Trp-OH). Tandem mass spectrometry was used to identify the structures of these new oxidation products. Free radicals derived from tryptophan oxidation under Fenton reaction were detected using as spin trap the DMPO. The free radical species originated during the oxidation reaction formed stable adducts with the spin trap, and these adducts were identified by ES-MS. New adducts of oxidized tryptophan radicals, namely monohydroxy-tryptophan and dihydroxy-Trp dimer radicals, with one and two DMPO spin trap molecules where identified. Tandem mass spectrometry was used to confirm the proposed structure of the observed adducts.     

Size Dependence of [n]Cycloparaphenylenes (n=5–12) in Electrochemical Oxidation

The oxidation processes of [n]cycloparaphenylenes ([n]CPPs) (n=5–12) were systematically investigated by cyclic and rotating disk electrode voltammetry. All CPPs underwent pseudo‐reversible two‐electron oxidation irrespective of ring size, forming the corresponding radical cations and then dications. The results were in sharp contrast to those observed for linear oligoparaphenylenes, which only undergo one‐electron oxidation. The difference in the first and second oxidation potentials in the CPP oxidation was affected by the ring size and became more significant as the decrease of CPP size. In other words, while the first oxidation from neutral CPP to the radical cation occurred faster as the size of CPP becomes smaller, the second oxidation from the radical cation to dication exhibited opposite size dependence.     

钛基纳米多孔金电极对甲醛氧化的电催化活性

采用水热法制备了钛基纳米金微粒修饰电极(Au/Ti)。扫描电镜图表明纳米金颗粒粒径大约为300 nm,在钛基体表面构成三维多孔网状结构。运用循环伏安,电位阶跃和交流阻抗等电化学技术研究了碱性介质中甲醛在Au/Ti电极上的电氧化行为。循环伏安图显示,甲醛在Au/Ti上的起始氧化电位在-0.90 V左右,相对于多晶金电极提前大约0.2 V,交流阻抗测试表明,甲醛在Au/Ti电极上电氧化表现出低的电荷传递电阻。研究结果表明钛基纳米金微粒修饰电极对甲醛氧化具有良好的电催化活性。     

Complex profiles of hydrophobic paralytic shellfish poisoning compounds in Gymnodinium catenatum identified by liquid chromatography with fluorescence detection and mass spectrometry

The presence of hydrophobic analogues of paralytic shellfish poisoning toxins (PSTs) was studied in a Portuguese strain of Gymnodinium catenatum by conventional pre-column oxidation HPLC after a prolonged acetonitrile gradient coupled with fluorescence detection. Prior separation of hydrophobic PSTs analogues from hydrophilic analogues was done by solid-phase extraction (SPE) partitioning on a C18 cartridge. Several unknown oxidation products, with emission spectra similar to known PSTs, appeared after periodate or hydrogen peroxide oxidation. The compounds producing these oxidation products could be grouped into three major sub-groups according to SPE partitioning. The first one eluting with 10 and 20% MeOH, produced the first set of oxidation products observed after the saxitoxin oxidation product. The second one eluting with 30-100% MeOH produced the second set of oxidation products. The third one eluted with acidified 90% MeOH produced the third and last set of oxidation products. Additionally, the oxidation products corresponding to decarbamoyl gonyautoxins and decarbamoyl saxitoxins were also abundant, resulting from ester cleavage of the benzoate side chain of these compounds during the oxidation. Analysis of these fractions by LC-MS demonstrated the second sub-group was constituted by analogues of the 11-hydroxysulfated GC1/GC2, while the third sub-group was constituted by analogues of GC3, which lack the 11-hydroxysulfate. In addition to GC1/GC2 and GC3, novel analogues differing by 16u could be related, respectively, to the N1-hydroxyl analogues of GC1-GC3, designated GC4-GC6. A novel family of GC analogues, differing, by 16u from GC1-GC6, were hypothesized to possess an extra hydroxyl in the benzoate side chain, existing in both N1-hydroxylated and non-N1-hydroxylated variants, and tentatively designated GC1a-GC6a. The first sub-group was hypothesized to constitute an additional novel family of GC analogues with a hydroxysulfate group instead of the hydroxyl group in the benzoate side chain, tentatively designated GC1b-GC6b.     

Thermal decomposition of silicon-containing chromium and cobalt γ-[(alkylthio)(alkoxy)phosphorylthio]acetylacetonates

Thermal decomposition of silicon-containing chromium and cobalt γ-[(alkylthio)(alkoxy)phosphorylthio]acetylacetonates in air was studied by derivatography. Thermal decomposition of the monomeric metal chelates containing triethylsilyl groups starts from the elimination of the substituent at P, followed by oxidation of the γ-thioacetylacetonate group. Thermal oxidation of polyorganylsiloxanes with phosphorus-substituted γ-thioacetylacetonate fragments starts with the oxidation of the γ-thioacetylacetonate groups, followed by oxidation of the alkoxy and vinylthio groups at phosphorus.     

Surface characterization and electrical property of carbon fibers modified by air oxidation

Polyacrylonitrile‐based carbon fibers were modified by oxidation in air, and a systematic study of surface groups and surface resistance at different treated temperatures was made. Progressive fiber weight loss occurred with increasing extents of air oxidation, and it was approximately proportional to the extent of air oxidation from the onset of oxidation up to 400 °C. At this point 4.4% of the initial fiber weight had been lost. A faster loss of weight occurred as the extent of air oxidation increased from 400 °C to 700 °C. X‐ray photoelectron spectroscopy studies (C 1s and O 1s) indicated that the oxygen/carbon atomic ratio rose rapidly from 2.64% (as‐received carbon fiber) to 42.83% as the oxidation temperature was increased to 400 °C. Fourier transform infrared spectra showed the relative intensity of the peaks at about 3440 cm^?1 from ―OH stretching vibrations and at 1634 cm^?1 from ―C?O stretching vibrations increased significantly at 400 °C. FESEM micrographs showed that as‐received fibers show relatively smooth surface. With oxidation temperature increasing, the fiber surface was rougher. The surface resistance of treated carbon fibers decreased obviously with increasing oxidation temperatures. The most decrease was about 100% at 400 °C. Copyright © 2014 John Wiley & Sons, Ltd.