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Roots of the carrot cultivars Vertou L.D. (resistant) and Long Chantenay (susceptible) were subjected to detailed chemical analysis to identify extracts and compounds influencing larval host-finding (preference/non-preference) behavior and to compare concentrations of these compounds in resistant and susceptible cultivars. Vertou yielded threefold less volatile material in headspace extracts of pureed roots. Extracts of chopped root in methanol, steam, hexane, and chloroform were inactive in behavioral assays. However, ether extracts were active and their hydrocarbon and carbonyl-rich fractions contained potent attractants. The principal constituent of the carbonyl-rich fraction of each cultivar was the carotatoxin complex comprising the neurotoxin falcarinol (carotatoxin), falcarindiol, and falcarindiol monoacetate, the latter compound here reported for the first time from carrot. Falcarinol (50 and 100 g) was active in a behavioral assay, and all three ingredients of the complex were potent electrophysiological stimuli, eliciting maximum single unit responses to source concentrations of 10 ng. Furthermore, the complex was more abundant by about 1000 g/root in Long Chantenay. As this comprised extra amounts of 70, 862, and 110 g of falcarinol, falcarindiol, and falcarindiol monoacetate, respectively, the observed differences seem both behaviorally and physiologically relevant. It is generally accepted that coevolution has transformed the role of many toxins into host-location cues, but this seems a relatively rare example of a neurotoxin (falcarinol) evincing, in decreased concentrations, nonpreference host resistance. This evolved response to a toxin present in large concentrations is contrasted with that totrans-2-nonenal, which paralyses and kills the larva and is present in only trace amounts in the root. 相似文献
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以醋酸正丁酯为内标物,采用毛细管气相色谱内标法测定1,4-丁二醇及其酯化产物的含量。结果表明:1,4-丁二醇、1,4-丁二醇单醋酸酯、1,4-丁二醇双醋酸酯的相对校正因子曲线分别在0.7090~41.30mg·mL-1、0.5980~41.82mg·mL-1、0.5429~39.10mg·mL-1范围内呈现良好的线性关系(R2≥0.9994),平均加标回收率为94.53%~103.20%,RSD≤4.72%。该方法操作简便、精密度高、重现性好、结果稳定可靠,可用于1,4-丁二醇及其酯化产物的含量测定。 相似文献
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研究了以三价铝盐为催化剂的乙酸氧乙基化反应的动力学规律,得到了描述该反应过程的动力学数学模型:r={exp[(1.83±180)-(8337-700)/T]+CKexp[(117.64±0.80)-(5996±483)/T]}Cc2H4O 相似文献
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以Mg(NO3)2为镁源,采用等体积浸渍法制备系列镁改性凹凸棒土催化剂Mg O/APT,利用XRD、BET、FT-IR和TPD对催化剂进行表征。结果表明,Mg O/APT催化剂具有与凹凸棒土相同的晶相结构;随着Mg O负载量的增加,Mg O/APT的碱强度和碱含量显著增加,较强酸量明显减少,弱酸酸位增加。在固定床反应装置上,考察催化剂气相催化转化1,4-丁二醇单醋酸酯反应性能。结果表明,催化剂表面的酸碱性对1,4-丁二醇单醋酸酯气相转化反应的产物分布有显著影响。酸性为主的催化剂APT上有利于1,4-丁二醇单醋酸酯发生分子内酯交换环化反应生成四氢呋喃;而适量酸-碱活性位有助于实现1,4-丁二醇单醋酸酯发生脱水-水解反应,生成3-丁烯-1-醇及3-丁烯-1-醇醋酸酯,过多碱性位有助于1,4-丁二醇单醋酸酯发生酯水解反应生成1,4-丁二醇。 相似文献
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以D001树脂为催化剂,用对苯二酚分别与乙酸酐和乙酸进行了反应实验并得到了对苯二酚单乙酸酯。结果表明:这两种方法均有较高的收率和选择性,采用乙酸酐为原料具有反应快,反应温度低的优点,但成本较高;以乙酸乙酯为溶剂对苯二酚与乙酸酐在80℃左右反应1h,对苯二酚单乙酸酯的收率为41.4%,采用乙酸为原料所需反应时间较长,但成长低,以甲苯为溶剂对苯二酚与过量的乙酸在110℃左右反应8h,对苯二酚单乙酸酯的收率为51.6%。 相似文献
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