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研究了卡比多巴中间体L-α-(3,4-二甲氧基苄基)-α-脲基丙酸(1)的合成新工艺.以L-α-(3,4-二甲氧基苄基)-α-氨基丙酸盐酸盐(2)为起始原料,首先在甲醇中氯化氢气体催化下进行氨基酸的酯化反应,得到L-α-(3,4-二甲氧基苄基)-α-氨基丙酸甲酯(3),收率90.7%;然后在三乙胺存在下,用双(三氯甲基)碳酸酯(BTC)法对氨基进行氯甲酰化、用氨气进行氨解,得到L-α-(3,4-二甲氧基苄基)-α-脲基丙酸甲酯(4),收率77.7%;最后用浓盐酸水解得到目标产物(1),收率91.5%,三步总收率达64.5%.重点考察了氯化氢气体、BTC及盐酸用量对反应收率的影响.采用核磁共振氢谱和碳谱,质谱对有关化合物进行了结构表征.该工艺条件温和,操作简便,环境友好,收率良好,具有潜在的工业应用前景. 相似文献
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探讨了合成(S)-1-(2-氯乙酰基)吡咯烷-2-甲腈的新工艺路线,即以L-脯氨酸为原料,经N-氯乙酰化、羧基氨基化和酰胺脱水反应合成目标化合物。目标化合物及各中间体的结构采用1HNMR和MS进行了确定。此外,详细研究了反应条件的影响,得到了优化的反应条件。目标产物的总收率可达42.3%。该合成路线具有原料便宜易得、操作简单、条件温和等优点,具有很好的市场应用前景。 相似文献
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L-4-硝基苯丙氨酸为合成众多药物的中间体.采用釜式反应器,以混酸(浓硫酸与浓硝酸)为硝化试剂对L-苯丙氨酸进行硝化反应,制备得到了目标产物.在浓硫酸与浓硝酸的体积比为2:1,反应温度为0℃,反应时间为3 h的工艺条件下,该法制备L-4-硝基苯丙氨酸的收率达到65.2%.该法在反应过程中得到的副产物,经~1H-NMR和~(13)C-NMR鉴定了其结构,证明其为两分子间的缩合产物,据此推测了反应可能的机理.为了减少分子间的缩合反应,采用管式反应器对苯丙氨酸的硝化反应进行探索,并用正交实验法对反应条件进行了优化,结果表明,反应温度为50℃,反应时间为5 min,混酸中浓硫酸与浓硝酸体积比为2:1,收率可达80.9%.与釜式反应相比,管式反应器能够有效避免分子间缩合的副反应,并能加快反应速率,提高反应效率. 相似文献
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以L-天冬氨酸和乙酸酐为原料,经脱水环化合成N-乙酰-L-天冬酸酐,然后与对氨基苯甲酸经N-酰化反应合成得到新化合物4-(2-乙酰氨基-3-羧基丙酰氨基)苯甲酸。通过Scifinder查询,未发现它的报道。研究了物料配比、反应温度、反应时间和溶剂等因素对产物收率的影响。优化条件为:无水乙醇作溶剂,n(N-乙酰-L-天冬酸酐)∶n(对氨基苯甲酸)=1∶1,反应温度为45℃,反应时间为3 h。优化条件下产物收率为78.7%。目标化合物经熔点、红外和核磁氢谱确证。 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria. 相似文献
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively.
There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized.
High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without
the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of
fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to
achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic
SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve
F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender
particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing,
and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing
or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually
preserves suspension stability during freezing.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago,
IL. Tied for first place in The John A. Gordon Best Paper Competition. 相似文献
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Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US
In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae
and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted
in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures
(release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species
(Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species
to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were
exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of
separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles
from the southeastern region of the US. 相似文献
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Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed. 相似文献
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中蓝晨光化工研究院有限公司《塑料工业》编辑部 《塑料工业》2009,37(3)
收集了2007年7月~2008年6月世界塑料工业的相关资料,介绍了2007~2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍. 相似文献
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中蓝晨光化工研究院《塑料工业》编辑部 《塑料工业》2007,35(3):1-25,67
收集了2005年7月~2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、通用热固性树脂(酚醛、聚氨酯、不饱和树脂、环氧树脂)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。 相似文献