共查询到19条相似文献，搜索用时 593 毫秒
1.
以对硝基苯基氯乙酰胺和对苯二酚为原料,在丙酮溶液中反应合成了N,N'-二(对硝基苯基)-2,2'-(对苯二氧基)二乙酰胺.在室温下采用自然扩散溶剂DMF和乙醇混合溶液(120,体积分散)得到了适合于X射线衍射分析的单晶体.依据晶体结构数据建立了分子结构模型,并利用量子化学半经验PM3方法进行结构优化计算和频率分析.Mulliken电荷布居分析表明分子中醚氧原子和羰基氧原子上都带有大量负电荷,并且与分子内的氢原子之间有氢键作用. 相似文献
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以对硝基苯胺和合成得到的2-溴-4-硝基苯胺为原料, 采用Gomberg-Bachmann芳基偶联反应,合成了两种电致磷光材料的关键中间体2-(4-硝基苯基)吡啶和2-(2-溴-4-硝基苯基)吡啶,并通过1HNMR确证了产物结构.研究结果表明,该合成方法简单、可行,芳基偶联产物2-(4-硝基苯基)吡啶和2-(2-溴-4-硝基苯基)吡啶的产率分别达到了22.5%和5.9%,其中前者超过文献报道水平,后者未见文献报道. 相似文献
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采用失重法及扫描电镜法研究了2-(3'-羟基苯基)-4,5-二(2’羟基苯基)咪唑(HHIP)在1MHCl溶液中对低碳铜的缓蚀作用,并对其缓蚀机理进行了探讨.研究结果表明:在1M HC1溶液中,该缓蚀剂对低碳钢的缓蚀效率可达到90％以上,最佳缓蚀效率达到95.12％,当缓蚀剂浓度为1mmol/L、实验温度为30℃,吸附成膜时间4h,缓蚀效率达最大值,此后基本不变.通过理论计算和分析该缓蚀剂在低碳铜的表面的吸附符合Langmuir吸附,且吉布斯自由能显示为自发过程. 相似文献
5.
以双酚A为起始原料,经过硝化、溴代反应,合成了2,2-二(3-溴-4-羟基-5-硝基苯基)丙烷,产率为83.1%.由IR、1HNMR、13CNMR和MS对目标产物的结构进行表征,所得数据与产物结构相符. 相似文献
6.
以蒎酮酸为原料,经Willgerodt反应合成了高蒎酸,产品收率达到62%。对高蒎酸产物进行了IR和1H NMR结构分析与表征。高蒎酸再经酰氯化、亲核取代、亲核加成反应,合成了5种双酰基硫脲衍生物,收率达到65%~80%。所合成的5种双酰基硫脲衍生物产品经IR、1H NMR进行了结构鉴定,分别为2,2'-(2,2-二甲基环丁基-1,3-二基)双[N-(苯基氨基硫代甲酰基)乙酰胺](5a)、2,2'-(2,2-二甲基环丁基-1,3-二基)双[N-(邻甲苯基氨基硫代甲酰基)乙酰胺](5b)、2,2'-(2,2-二甲基环丁基-1,3-二基)双[N-(间甲苯基氨基硫代甲酰基)乙酰胺](5c)、2,2'-(2,2-二甲基环丁基-1,3-二基)双[N-(对甲苯基氨基硫代甲酰基)乙酰胺](5d)和2,2'-(2,2-二甲基环丁基-1,3-二基)双[N-(2,4-二甲基苯基氨基硫代甲酰基)乙酰胺](5e)。 相似文献
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指出了4-(N,N-二甲氨基)-丁醛缩二乙醇是合成阿莫曲坦的重要中间体,阿莫曲坦是一种具有高度选择性的治疗偏头痛5-HT1B/1D受体激动剂,它克服了第一代曲坦类药物的某些不良反应,并且具有很高的血管选择性,耐受性好,不良反应轻微且短暂。针对阿莫曲坦的合成路线进行了阐述,且对4-(N,N-二甲氨基)-丁醛缩二乙醇合成路线进行了研究,结果表明:以1-溴-3-氯丙烷为原料,经过氨化,得到3-(N,N-二甲氨基)-1-氯丙烷,3-(N,N-二甲氨基)-1-氯丙烷和原甲酸三乙酯经格氏加成反应生成4-(N,N-二甲氨基)-丁醛缩二乙醇,总收率为53%。 相似文献
8.
脱氢枞酸与二氯亚砜反应得到脱氢枞酸酰氯,再与氨基硫脲反应制备脱氢枞基氨基硫脲,脱氢枞基氨基硫脲再与芳香醛和乙酰乙酸乙酯反应,合成了10个脱氢枞酸酰胺基-3,4-二氢嘧啶酮衍生物,分别为:4-苯基-6-甲基-1-脱氢枞酸酰胺基-3,4-二氢嘧啶-2-硫酮(3a)、4-(4-甲氧基苯基)-6-甲基-1-脱氢枞酸酰胺基-3,4-二氢嘧啶-2-硫酮(3b)、4-(2-甲氧基苯基)-6-甲基-1-脱氢枞酸酰胺基-3,4-二氢嘧啶-2-硫酮(3c)、4-(4-甲基苯基)-6-甲基-1-脱氢枞酸酰胺基-3,4-二氢嘧啶-2-硫酮(3d)、4-(4-溴苯基)-6-甲基-1-脱氢枞酸酰胺基-3,4-二氢嘧啶-2-硫酮(3e)、4-(4-对三氟甲基苯基)-6-甲基-1-脱氢枞酸酰胺基-3,4-二氢嘧啶-2-硫酮(3f)、4-(4-氯苯基)-6-甲基-1-脱氢枞酸酰胺基-3,4-二氢嘧啶-2-硫酮(3g)、4-(2,6-二氯苯基)-6-甲基-1-脱氢枞酸酰胺基-3,4-二氢嘧啶-2-硫酮(3h)、4-(2-硝基苯基)-6-甲基-1-脱氢枞酸酰胺基-3,4-二氢嘧啶-2-硫酮(3i)、4-(3-硝基苯基)-6-甲基-1-脱氢枞酸酰胺基-3,4-二氢嘧啶-2-硫酮(3j)。通过FT-IR、MS、~1H NMR和13C NMR表征了目标化合物结构。选取猴胚胎肾细胞MA-104作为受试细胞,测试了化合物3a～3j的细胞毒性;利用四甲基偶氮唑蓝(MTT)比色法测试了这些化合物对单纯疱疹病毒Ⅰ型(HSV-1)的体外抗病毒活性。数据显示,该系列衍生物的细胞毒性较小,与阳性对照药物利巴韦林相比,化合物3a、3b、3d、3e、3h、3i和3j体现出更小的细胞毒性;化合物3j具有较好的抑制HSV-1活性,半数抑制浓度(IC50)0.465 g/L,选择指数(SI)12.18,达到与阳性对照药物利巴韦林相近的抑制活性(IC50为0.156 g/L,SI为12.6),其余样品具有较弱的抑制HSV-1活性。 相似文献
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《林产化学与工业》2019,(5)
以1,8-对■烷二乙酰胺为原料,通过酸催化消去和碱催化水解两步反应制得3-对■烯-1-胺,采用单因素和正交试验考察了不同条件对反应的影响。酸催化消去反应的最佳反应条件为:20 mmol对■烷二乙酰胺,35 mL质量分数12.5%H_2SO_4(24 mmol)溶液,反应时间8 h,N-乙酰基-3-对■烯-1-胺产率41.6%;碱催化水解的最佳反应条件为:n(N-乙酰基-3-对■烯-1-胺)∶n(NaOH)为1∶7,30 mL乙二醇,反应时间11 h,反应温度170℃,3-对■烯-1-胺产率82.2%,总产率为34.2%。3-对■烯-1-胺经减压精馏到纯度97%,采用ESI-MS、FT-IR、~1H NMR及~(13)C NMR等仪器分析进行表征,确定了产物结构。 相似文献
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以ω(Fe)=5%的FeCl3·6H2O/C为催化剂,用ω (NH2NH2)=80%的水合肼,在乙醇溶剂中将2,2-二(4-羟基-3-硝基)苯基丙烷还原成为阻燃剂的中间体2,2-二(4-羟基-3-氨基)苯基丙烷.实验条件:用0.3 g的催化剂(每10 mmol反应物),反应物与水合肼的摩尔比为1∶4.5,控制反应温度为70℃,反应时间为3.5 h,目标产物的产率为93.0%,纯度为98.5%,考察9种金属离子对催化活性的影响.结果表明:Pb2 会引起催化剂中毒;Mg2 、Cu2 和Zn2 钝化了催化剂的催化活性;Ba2 和Cr3 对反应几乎不影响;只有Al3 、Ni2 、Ti4 3种离子能活化催化剂,从而使反应速度加快,但这3种金属离子单独作为催化剂时都没有催化活性. 相似文献
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分别以左旋龙脑(艾片)、右旋龙脑(冰片)、艾片及冰片组成的外消旋龙脑为原料,与草酰氯发生间接酯化反应合成了3种光学活性的草酸龙脑酯,经乙醇重结晶后GC纯度99.9%,通过手性液相色谱分析证明合成的消旋龙脑酯中同时含有左旋体、内消旋体和右旋体,其质量比近似为1∶2∶1。利用二维核磁共振技术~1H-~1H COSY、HSQC及HMBC等手段对左旋的草酸龙脑酯的碳原子及氢原子进行归属,并采用GC-MS、FT-IR、~1H NMR、~(13)C NMR等对比研究了所合成的左旋、右旋及消旋的草酸龙脑酯的谱学性质,还进一步对比了合成的消旋龙脑酯与人工混合而成的外消旋体的谱学特征。结果表明:左旋、右旋及人工混合的外消旋的草酸龙脑酯虽然旋光性不同,但其谱学性质没有明显的差别,而由外消旋龙脑与草酰氯合成得到的消旋产物中所含的内消旋体,其分子两侧的碳氢原子却表现出比较明显的核磁化学环境及谱学性质差异,主要体现在8-与8'-、3-与3'-位上的氢及1-与1'-、3-与3'-、11-与11'-位上的碳的化学位移值不相等。 相似文献
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[目的]探究油松PtGSTU1结构与功能的关系,探讨油松PtGSTU1蛋白的单体稳定性。[方法]利用同源建模模拟PtGSTU1的三维结构,推测其N末端18位精氨酸(Arg18)和C末端103位天冬氨酸(Asp103)能够形成氢键来稳定蛋白单体结构。利用定点突变,分别将Arg18和Asp103突变为具有不同极性和构象的氨基酸残基,检测其蛋白的催化活性及结构稳定性。[结果]6个Arg18突变体均无法获得高纯度的具有正确折叠的可溶蛋白,而Asp103突变体可以表达为可溶蛋白,Asp103突变体对不同底物的催化活性和亲和力明显低于野生型,对经典底物CDNB和GSH反应的催化速率(Vmax)降低了至少9倍,对底物的催化效率(kcat/Km)也明显降低。[结论]Arg18和Asp103之间形成的氢键对稳定PtGSTU1单体结构具有重要作用,由于植物GST蛋白N端的保守性和C端结构域的多变性,Arg18的突变对结构和活性的影响大于Asp103,同时预示着C端结构域中可能存在其他氨基酸位点能够与18位精氨酸形成氢键,从而稳定蛋白单体折叠结构。 相似文献
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We studied the effects of O(3) uptake on conductance (g(wv)) and photosynthesis (A) in needles of ponderosa pine (Pinus ponderosa Laws.) seedlings exposed for 70 days to one of three O(3) regimes-Low-O(3) (0.1 micro mol mol(-1) daily peak), High-O(3) (0.2 micro mol mol(-1) daily peak), and Low/High-O(3) (alternating 2 days Low-O(3) and 2 days High-O(3)). Seedlings exposed to charcoal-filtered air served as controls. Total O(3) exposures, expressed as ppm-h (the sum of the average hourly concentration in ppm ( micro mol mol(-1)) over the exposure period), were 77, 135, 105 and 4 for the Low-O(3), High-O(3), Low/High-O(3) and control treatments, respectively. Conductance (g(wv)) declined to about 60% of the value in control seedlings by Day 6 in seedlings in the High-O(3) treatment and by Day 37 in seedlings in the Low/High-O(3) treatment, but g(wv) did not decline at all in seedlings in the Low-O(3) treatment. At the end of the 70-day experiment, cumulative O(3) uptake, calculated from measured g(wv) values and assuming an internal O(3) concentration of zero, was 12.2, 13.5, and 14.7 mmol m(-2) for seedlings in the Low-O(3), Low/High-O(3), and High-O(3) treatments, respectively; however, O(3) uptake was reduced by 0, 24, and 36%, respectively, from that expected if there had been no decline in g(wv). With increasing total O(3) exposure, A declined, but the reduction was not strictly cumulative, i.e., A measured on Days 49 and 70 was similar for a given treatment even though both total O(3) exposure and uptake had increased. At the end of the experiment, A at near saturating CO(2) (1000 micro mol mol(-1)) and saturating photosynthetic photon flux density was reduced by about 25, 40 and 50% in seedlings in the Low-O(3), Low/High-O(3) and High-O(3) treatments, respectively, compared to the control seedlings. The ratio of internal to external CO(2) concentrations, an indicator of relative change in stomatal limitation of A, did not change over time and did not differ among treatments, suggesting that A and g(wv) decreased in parallel. After 40-60 days without O(3), A of seedlings in all O(3) treatments was not significantly different. Our data indicate that O(3)-induced stomatal closure was a result of reduced A and that decreased g(wv) reduced O(3) uptake to a rate that needles of ponderosa pine could tolerate without exhibiting further reductions in gas exchange capacity. 相似文献
14.
Kostiainen K Kaakinen S Warsta E Kubiske ME Nelson ND Sober J Karnosky DF Saranpää P Vapaavuori E 《Tree physiology》2008,28(5):805-813
We investigated the interactive effects of elevated concentrations of carbon dioxide ([CO(2)]) and ozone ([O(3)]) on radial growth, wood chemistry and structure of five 5-year-old trembling aspen (Populus tremuloides Michx.) clones and the wood chemistry of paper birch (Betula papyrifera Marsh.). Material for the study was collected from the Aspen FACE (free-air CO(2) enrichment) experiment in Rhinelander, WI, where the saplings had been exposed to four treatments: control, elevated [CO(2)] (560 ppm), elevated [O(3)] (1.5 x ambient) and their combination for five growing seasons. Wood properties of both species were altered in response to exposure to the treatments. In aspen, elevated [CO(2)] decreased uronic acids (constituents of, e.g., hemicellulose) and tended to increase stem diameter. In response to elevated [O(3)] exposure, acid-soluble lignin concentration decreased and vessel lumen diameter tended to decrease. Elevated [O(3)] increased the concentration of acetone-soluble extractives in paper birch, but tended to decrease the concentration of these compounds in aspen. In paper birch, elevated [CO(2)] decreased and elevated [O(3)] increased starch concentration. The responses of wood properties to 5 years of fumigation differed from those previously reported after 3 years of fumigation. 相似文献
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The stable oxygen isotope ratio (delta(18)O) of tree-ring cellulose is jointly determined by the delta(18)O of xylem water, the delta(18)O of atmospheric water vapor, the humidity of the atmosphere and perhaps by species-specific differences in leaf structure and function. Atmospheric humidity and the delta(18)O of water vapor vary seasonally and annually, but if the canopy atmosphere is well mixed, atmospheric characteristics should be uniform among co-occurring trees. In contrast, xylem water delta(18)O is determined by the delta(18)O of water being drawn from the soil, which varies with depth. If co-occurring trees draw water from different soil depths, this soil-water delta(18)O signal would be manifest as differences in delta(18)O among the trees. We examined the variation in tree ring delta(18)O, over eight decades during the 20th Century, among three species co-occurring in natural forest stands of the northern Rocky Mountains in the USA. We sampled 10 Douglas-firs (Pseudotsuga menziesii (Mirb.) Franco var. glauca), 10 ponderosa pines (Pinus ponderosa Laws.) and seven western white pines (Pinus monticola Dougl.). As expected, variation in atmospheric conditions was recorded in the delta(18)O of the cellulose produced in a given year, but observed climatic correlations with delta(18)O were weak. Significant correlations with June climate data included: daily maximum temperature (r = 0.29), daily minimum temperature (r = -0.25), mean temperature (r = 0.20), mean daily precipitation (r = -0.54), vapor pressure deficit (r = 0.32) and solar radiation (r = 0.44). Lagged effects were observed in Douglas-fir and western white pine. In these species, the delta(18)O of a given annual ring was correlated with the delta(18)O of the previous ring. Ponderosa pine showed no significant autocorrelation. Although the species means were correlated among years (r = 0.67 to 0.76), ponderosa pine was consistently enriched in delta(18)O relative to the other species; differences were close to 2 per thousand and they are steadily increasing. Relative to the mean for the three species, ponderosa pine is becoming steadily more enriched (-1.0 per thousand). In contrast, Douglas-fir is being steadily depleted and western pine is intermediate, with an enrichment of 0.5 per thousand. Because all trees were exposed to the same atmospheric conditions, the differences in delta(18)O observed between species are likely due either to differences in the depth of water extraction or leaf function. If the former, presumably ponderosa pine has steadily taken up more water from near the soil surface and Douglas-fir has shifted uptake to a greater depth. If the latter, we suggest the pronounced changes in leaf-water delta(18)O are a result of changes in leaf structure and function with tree size and age. 相似文献
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Rios MY López-Martínez S López-Vallejo F Medina-Franco JL Villalobos-Molina R Ibarra-Barajas M Navarrete-Vazquez G Hidalgo-Figueroa S Hernández-Abreu O Estrada-Soto S 《Fitoterapia》2012,83(6):1023-1029
The aim of the current study was to investigate the vasorelaxant activity of five structurally-related triterpenic acids namely ursolic (1), moronic (2), morolic (3), betulinic (4) and 3,4-seco-olean-18-ene-3,28-dioic (5) acids. The vasorelaxant effect of compounds 1-5 were determined on endothelium-denuded and endothelium-intact rat aortic rings pre-contracted with noradrenaline (0.1 μM). All compounds showed significant relaxant effect on endothelium-intact vessels in a concentration-dependent manner (p<0.05). Ursolic, moronic and betulinic acids were the most potent vasorelaxant agents with 11.7, 16.11 and 58.46 μM, respectively. Since vasorelaxation was blocked by L-NAME, while indomethacin did not inhibit the effect, endothelium-derived nitric oxide seems to be involved in triterpenic 2 and 3 mode of action. Compounds 1-5 were docked with a crystal structure of eNOS. Triterpenes 1-5 showed calculated affinity with eNOS in the C1 and C2 binding pockets, near the catalytic site; Ser248 and Asp480 are the residues that make hydrogen bonds with the triterpene compounds. 相似文献
17.
In the present experiment, the single and combined effects of elevated temperature and ozone (O(3)) on four silver birch genotypes (gt12, gt14, gt15 and gt25) were studied in an open-air field exposure design. Above- and below-ground biomass accumulation, stem growth and soil respiration were measured in 2008. In addition, a (13)C-labelling experiment was conducted with gt15 trees. After the second exposure season, elevated temperature increased silver birch above- and below-ground growth and soil respiration rates. However, some of these variables showed that the temperature effect was modified by tree genotype and prevailing O(3) level. For instance, in gt14 soil respiration was increased in elevated temperature alone (T) and in elevated O(3) and elevated temperature in combination (O(3) + T) treatments, but in other genotypes O(3) either partly (gt12) or totally nullified (gt25) temperature effects on soil respiration, or acted synergistically with temperature (gt15). Before leaf abscission, all genotypes had the largest leaf biomass in T and O(3) + T treatments, whereas at the end of the season temperature effects on leaf biomass depended on the prevailing O(3) level. Temperature increase thus delayed and O(3) accelerated leaf senescence, and in combination treatment O(3) reduced the temperature effect. Photosynthetic : non-photosynthetic tissue ratios (P : nP ratios) showed that elevated temperature increased foliage biomass relative to woody mass, particularly in gt14 and gt12, whereas O(3) and O(3) + T decreased it most clearly in gt25. O(3)-caused stem growth reductions were clearest in the fastest-growing gt14 and gt25, whereas mycorrhizal root growth and sporocarp production increased under O(3) in all genotypes. A labelling experiment showed that temperature increased tree total biomass and hence (13)C fixation in the foliage and roots and also label return was highest under elevated temperature. Ozone seemed to change tree (13)C allocation, as it decreased foliar (13)C excess amount, simultaneously increasing (13)C excess obtained from the soil. The present results suggest that warming has potential to increase silver birch growth and hence carbon (C) accumulation in tree biomass, but the final magnitude of this C sink strength is partly counteracted by temperature-induced increase in soil respiration rates and simultaneous O(3) stress. Silver birch populations' response to climate change will also largely depend on their genotype composition. 相似文献
18.
将乙酸制浆法废液中的木质素进行提取和精制,采用红外光谱(FTIR)、31P-NMR谱和凝胶渗透色谱(GPC)对其结构进行表征,并利用乙酸木质素、聚醚多元醇和甲苯二异氰酸酯在发泡剂和催化剂的条件下合成聚氨酯硬泡。采用TG、DSC和压缩测试对聚氨酯硬泡的热学和力学性能进行研究,并用扫描电子显微镜观察聚氨酯硬泡的泡孔结构。结果表明:乙酸木质素作为多羟基聚合物,可以部分代替聚醚多元醇和异氰酸酯发生反应制备聚氨酯材料;当乙酸木质素添加量为5%时,聚氨酯硬泡的压缩强度达到1.325MPa,比未添加木质素的泡沫高出约63%,此时的压缩模量也达到0.181MPa;随着乙酸木质素添加量增加,乙酸木质素基聚氨酯硬泡的最快分解温度下降,而玻璃化转变温度没有明显升高;乙酸木质素基聚氨酯硬泡泡孔平整均匀。 相似文献
19.
木聚糖酶预处理对麦草化学机械浆可漂性及白度的改善 总被引：9，自引：1，他引：9
探讨了以玉米芯片为碳源制备木聚糖酶及麦草化学机械浆经该木聚糖酶预处理后可漂性和白度的改善效果。结果表明，直接以玉米芯为底物、里氏木霉为菌种产酶效果较好，当底物浓度为18g/L时，木聚糖酶活力可达38．34IU／mL。木聚糖酶预处理有利于改善麦草化机浆的可漂性，促进其过氧化氢漂白，有提高漂白浆白度，降低漂剂消耗。研究表明，当经单段H2O2漂至相同白度时，木聚糖酶预处理后可节约50％的H2O2用量。若麦草CMP酶处理后采用高浓度两段过氧化氢漂白，即XP3P3漂序（H2O2总量为6％0时，白度可达60％（ISO）以上。 相似文献