L-谷氨酸的消旋研究及DL-谷氨酸的制备

研究了L-谷氨酸在不同pH、溶剂、温度、反应时间下的消旋过程,并由最佳消旋条件制备DL-谷氨酸。实验结果表明:当乙酸浓度大于95%、以水杨醛为催化剂、温度90℃、n(水杨醛)∶n(谷氨酸)=0.1时,消旋效果最好。     

与环境友好的化学-生物法制备D-精氨酸和L-瓜氨酸

L-精氨酸在水溶液中利用自身所产生的碱性溶液,用n(水杨醛):n(1-精氨酸)=0.1:1的水杨醛为催化剂,L-精氨酸可以快速消旋为DL-精氨酸.后以DL-精氨酸为底物,利用粪链球菌(streptococcus faecalis)精氨酸脱亚胺酶对L-精氨酸的专一脱亚胺作用,同时制备D-精氨酸和L-瓜氨酸,分别以92.3%、94.2%产率获得光学纯的D-精氨酸和L-瓜氨酸.     

α-葡萄糖五乙酸酯的合成研究

以对甲苯磺酸为催化剂,利用α或β-葡萄糖五乙酸酯合成过程的副产物混合型葡萄糖五乙酸酯在溶剂中构型转化合成α-葡萄糖五乙酸酯,研究了合成的最佳反应条件。结果表明最佳条件为：溶剂选用w （乙酸酐）=80%的乙酸酐/乙酸混合溶剂,催化剂的用量为副产物质量的10%,反应时间3 h,反应温度90℃,合成总收率可达75.4%。最后探讨了可能的反应机理。     

L-组氨酸和L-脯氨酸消旋动力学的研究

L-组氨酸和L-脯氨酸在醛的催化下,可在羧酸溶剂中发生消旋。氨基酸的消旋反应为一级反应。消旋速率因羧酸溶剂的不同而异:L-组氨酸在乙酸溶剂中消旋最快,而L-脯氨酸在正丁酸溶剂中最快。随反应温度的提高,消旋速率加快。L-脯氨酸的消旋速率常数与反应温度的关系可表示为: 67088R494573eRTk-= 另外实验表明,L-组氨酸和L-脯氨酸消旋反应的合适催化剂分别应为水杨醛和正丁醛,并确定催化剂的用量与氨基酸的摩尔比以0.1为佳。同时也论述了氨基酸消旋的反应机理。     

(R)-(+)-N,N-二甲基-3-羟基-3-(2-噻吩基)丙胺的消旋

为提高抗抑郁药度洛西汀合成收率,降低生产成本,研究了中间体拆分副产物(R)-(+)-N,N-二甲基-3-羟基-3-(2-噻吩基)丙胺在不同有机羧酸溶剂、反应温度、反应时间、共溶剂剂量下的消旋化反应。实验表明,以乙酸作溶剂,温度90℃,x(水杨醛)=0.1作共溶剂,反应8 h,最后消旋率达到100%,收率为70%。在同样实验条件下将反应投料量扩大至200 g,平均消旋率达99.2%,平均收率达90.8%,所得消旋体可以重新用于光学拆分及合成产物度洛西汀。     

D-对羟基苯甘氨酸的制备

采用乙醛酸法合成DL-对羟基苯甘氨酸,再用氯化亚砜法将DL-对羟基苯甘氨酸酯化后与L-(+)-酒石酸成盐,甲醇做溶剂,水杨醛作消旋剂,利用不对称转化法制得D-对羟基苯甘氨酸甲酯酒石酸盐,经水解,中和得到D-对羟基苯甘氨酸。考察了酯化条件及消旋剂的用量,并对水解条件进行了优化。拆分总收率为70.7%,光学纯度99.8%。同时,采用1H NMR对化合物物结构进行了表征。     

D-色氨酸的合成工艺研究

在甲醇钠碱性条件下,以芦竹碱和N-乙酰氨基丙二酸二乙酯为原料进行缩合反应,缩合产物在4%的氢氧化钠水溶液中选择性水解脱羧得到N-乙酰-DL-色氨酸,然后在10%氢氧化钠水溶液中水解得到DL-色氨酸。DL-色氨酸用D-酒石酸拆分,并在苯甲醛催化下实现不对称转化,得到D-色氨酸D-酒石酸盐,最后用三乙胺中和得到目标产物D-色氨酸。确定了缩合和拆分步骤的适宜工艺条件。缩合步骤:甲醇钠摩尔量为芦竹碱的20%,n(芦竹碱)∶(N-乙酰氨基丙二酸二乙酯)=1∶1.2;拆分步骤:乙酸为溶剂,70℃反应,苯甲醛摩尔量为DL-色氨酸的10%,n(DL-色氨酸)∶n(D-酒石酸)=1∶2。     

间苯二胺选择性乙酰化合成间氨基乙酰苯胺

以间苯二胺为原料，盐酸（36%）为氨基保护剂，乙酸和乙酸酐混合为酰化剂，氯化钠为抑制剂，经选择性乙酰化反应合成染料中间体间氨基乙酰苯胺，通过FT-IR、1H NMR对产物结构进行了表征。考察了投料比、溶剂水用量、反应温度、反应时间、氯化钠用量对产品收率和纯度的影响，并得到最佳工艺条件：n(间苯二胺)∶n(盐酸)∶n(乙酸)∶n(乙酸酐)=1∶1∶1∶0.6、溶剂水用量为20 g、反应温度为70℃、反应时间为4 h、氯化钠用量为7g，母液可循环套用多次。通过对比发现乙酸和乙酸酐混合为酰化剂，既能减少废酸排放又能节省成本，抑制剂的加入可提高产品的收率及纯度。在此优化条件下间氨基乙酰苯胺收率为93.1%，纯度为98.5%。     

α-苯乙胺拆分研究

本文采用不溶于水的L-谷氨酸作为拆分剂,在混合溶剂中对消旋α-苯乙胺进行拆分,拆分剂L-谷氨酸可以直接酸化高收率的回收.较好的反应条件是:拆分剂的用量1.05 mol,甲苯用量190 g,稀硫酸浓度15％.S-(-)-α-苯乙胺收率89％,比旋光度:-39.4°;回收混合a-苯乙胺收率92.5％;回收拆分剂收率95.9...     

不对称转换拆分对羟基苯甘氨酸的研究

以醋酸水溶液为溶剂,邻甲苯磺酸为拆分剂,水杨醛为消旋剂,用不对称转换拆分DL-对羟基苯甘氨酸为D-对羟基苯甘氨酸。考察了影响拆分收率和纯度的因素,其适宜条件：醋酸水溶液的浓度为97％,诱导结晶的温度为100℃。     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

Insect antifeedant properties of anthranoids from the genusVismia

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.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009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、环氧树脂、不饱和聚酯树脂)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。