阳离子交换树脂催化合成丙烯酸环己酯

以丙烯酸和环己烯为原料,磺酸基苯乙烯系强酸性阳离子交换树脂为催化剂合成丙烯酸环己酯,考察了反应温度、催化剂用量、烯酸摩尔比、反应时间对酯化反应的影响.结果表明,合成丙烯酸环己酯的最佳条件为:反应温度85℃,催化剂质量分数5%,n(酸)∶n(烯)=2∶1,反应时间5h.在最佳工艺条件下,环己烯转化率为87.2%,丙烯酸环...     

丙烯酸(2-氯乙基)酯的合成研究

采用强酸性阳离子交换树脂为催化剂,以丙烯酸、氯乙醇为原料合成了丙烯酸(2'-氯乙基)酯,分别研究了反应温度、反应时间、原料配比、催化剂用量和阻聚剂用量等条件对合成反应的影响。得到了合成丙烯酸(2'-氯乙基)酯最适宜的条件是:反应温度为85～95℃,反应时间3h,原料摩尔比n(丙烯酸)∶n(氯乙醇)为0.2∶0.25,丙烯酸为0.2mol的情况下,阻聚剂的用量为0.15g,催化剂的用量1g,丙烯酸(2'-氯乙基)酯的收率可达到91.59%以上。     

丙烯酸(2-氯乙基)酯的合成研究简

采用强酸性阳离子交换树脂为催化剂,以丙烯酸、氯乙醇为原料合成了丙烯酸（2’-氯乙基）酯,分别研究了反应温度、反应时间、原料配比、催化剂用量和阻聚剂用量等条件对合成反应的影响.得到了合成丙烯酸（2’-氯乙基）酯最适宜的条件是：反应温度为85 ～ 95℃,反应时间3h,原料摩尔比n（丙烯酸）∶n（氯乙醇）为0.2：0.25,丙烯酸为0.2 mol的情况下,阻聚剂的用量为0.15g,催化剂的用量1 g,丙烯酸（2’-氯乙基）酯的收率可达到91.59％以上.     

强酸性阳离子交换树脂催化合成对羟基苯乙酸甲酯

以对羟基苯乙酸和甲醇为原料,强酸性阳离子交换树脂为催化剂,研究了催化剂种类、反应时间、反应温度、原料配比、催化剂用量及催化剂重复使用次数对反应的影响,确定了反应的最佳工艺条件为:反应温度为65~70℃,反应时间为4 h,醇酸摩尔比为4∶1,催化剂用量为反应物料总质量的1.5%,酯化收率为85.0%,产品纯度可达到98.5%。使用的催化剂732型强酸性阳离子交换树脂不经处理可重复使用10次以上,显示了较好的稳定性,同时具有催化活性好、价格低廉、不腐蚀设备、无环境污染等优点。     

阳离子交换树脂催化合成乙酸大茴香酯的研究

在强酸性阳离子交换树脂存在下,以大茴香醇和乙酸为原料合成乙酸大茴香酯.考察了反应时间、原料配比和催化剂用量等因素对合成反应的影响,确定了较佳的工艺条件:n(大茴香醇)∶n(乙酸)=1.0∶3.0,大茴香醇为1.0 mol,带水剂甲苯为180 mL,强酸性阳离子交换树脂用量为16.0 g,101℃～105℃回流反应12 h.乙酸大茴香酯的平均收率可达到92.5%,产品纯度达99.3%.     

强酸性阳离子交换树脂催化合成二甲基硅油的研究

以八甲基环四硅氧烷(D4)、六甲基二硅氧烷(MM)为原料,强酸性阳离子交换树脂为催化剂,通过平衡反应合成了二甲基硅油。通过单因素试验法考察了反应温度、反应时间、阳离子交换树脂的氢离子含量、粒径及用量对二甲基硅油黏度的影响,并考察了阳离子交换树脂催化剂的连续使用寿命。结果表明,适宜作合成甲基硅油催化剂的强酸性阳离子交换树脂的氢离子质量摩尔浓度为5 mmol/g、粒径为0.6～0.8 mm,最佳添加量为反应物质量的6%,反应时间为5 h,反应温度为80～90℃,阳离子交换树脂的连续使用寿命为200 h左右。     

阳离子交换树脂催化合成苹果酯- B的研究

采用强酸性阳离子交换树脂为催化剂,以乙酰乙酸乙酯、1,2-丙二醇为原料合成苹果酯-B。分别研究了反应温度、反应时问、原料配比和催化剂用量等条件对合成反应的影响。得到了合成苹果酯-B最适宜的条件：104℃,反应3h,乙酰乙酸乙酯与1,2-丙二醇摩尔比为1：1．45,带水剂环己烷为15mL（乙酰乙酸乙酯为0．15mol的情况下）,强酸性阳离子交换树脂的用量为总物料质量的5．25％。苹果酯-B的收率可达到96．8l％,产品中苹果酯-B质量分数为99．8％。     

强酸性阳离子交换树脂催化合成丁酮乙二醇缩酮

以强酸性阳离子交换树脂为催化剂,通过丁酮和乙二醇反应合成丁酮乙二醇缩酮。探讨了强酸性阳离子交换树脂对缩酮反应的催化活性,较系统的研究了醇酮物质的量比、催化用量和反应时间等因素对产品收率的影响。实验表明:强酸性阳离子交换树脂是合成丁酮乙二醇缩酮的良好催化剂,在醇酮摩尔比为1:2,催化剂用量为反应物总质量的0.5%,环己烷为带水剂,反应时间3h的优化条件下,丁酮乙二醇缩酮的产率达76.5%,催化剂可重复使用。     

强酸性阳离子交换树脂催化合成乙酸脱氢芳樟酯

采用强酸性阳离子交换树脂为催化剂,以脱氢芳樟醇和乙酸酐为原料合成乙酸脱氢芳樟酯,考察了离子交换树脂的处理方法、催化剂用量以及反应条件等因素对反应结果的影响。当n(脱氢芳樟醇):n(乙酸酐)=1:1.2、反应温度80℃、催化剂用量为醇酐总质量的5%、反应时间为3.5h时,反应的转化率和选择性分别达到80%和90%以上。     

阳离子交换树脂催化合成乙酰乙酸乙酯乙二醇缩醛

在强酸性阳离子交换树脂催化剂存在下，以乙酰乙酸乙酯、乙二醇为原料合成缩醛，分别研究了反应温度、反应时间、原料配比、催化剂用量等条件对合成反应的影响，确定了最佳工艺条件。该方法合成苹果酯的最佳工艺条件是：反应温度为97℃，反应时间4h，n(乙酰乙酸乙酯)：n(乙二醇)：0．15：0．21；带水剂环己烷为15mL(乙酰乙酸乙酯为0．15mol的情况下)；强酸性阳离子交换树脂用量为总物料质量的5．8％。苹果酯的收率可达到95．02％，产品纯度w(苹果酯)达到99．5％以上。     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.